AERCO DW User Manual

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HE-111

Double-Wall Heat Exchanger – Model DW

USER MANUAL

OMM-0065_0B

Applicable to Serial Numbers H-09-430 and above

Installation, Operation

& Maintenance Instructions

Double-Wall Heat Exchanger

Model DW

Printed in U.S.A. Rev B Mar 2013

HE-111

Double-Wall Heat Exchanger – Model DW

USER MANUAL

Telephone Support

Direct to AERCO Technical Support (8 to 5 pm EST, Monday through Friday)

(800) 526-0288

AERCO International, Inc. 100 Oritani Dr. Blauvelt, NY 10913

OMM-0065_0A

The information contained in this operation and mainten anc e manual is subject to change without noti ce fro m AERCO International, Inc.

AERCO makes no warranty of any kind with respect to this material, including but not limited to implied warranties of merchantabilit y and fitnes s f or a particular applicati o n. AER C O International is liable for neither errors appearing in this manual, nor for incidental or consequential damages occurring in connection with the furnishing, performance, or use of this material.

HE-111 − CONTENTS

iii

TABLE OF CONTENTS

CHAPTER 1 GENERAL INFORMATION

1.1 INTRODUCTION .............................................................................................. 1-1

1.2 MECHANICAL OVERVIEW............................................................................ 1-1

1.3 ELECTRONIC CONTROL SYSTEM ............................................................... 1-2

1.4 OPTIONS AND ACCESSORIES ...................................................................... 1-3

1.4.1 MODBUS Communication Option ........................................................................... 1-3

1.4.2 Accessories ................................................................................................................ 1-3

CHAPTER 2 INSTALLATION

2.1 INTRODUCTION .............................................................................................. 2-1

2.2 RECEIVING, UNPACKING AND INSTALLING ........................................... 2-1

2.3 MAKING THE PIPING CONNECTIONS ........................................................ 2-5

2.4 INSTALLING THE CXT-E ELECTRONIC CONTOL SYSTEM ................... 2-6

2.4.1 Accessing the Control Box Interior ........................................................................... 2-7

2.4.2 Connecting the AC Power to the Control Box .......................................................... 2-8

2.4.3 Wiring the CXT-E Actuator ...................................................................................... 2-9

2.4.4 Verifying the Pre-wired Connections ........................................................................ 2-9

2.4.5 Wiring the Temperature Controller to the MO DB U S Contro l System ..................... 2-9

2.4.6 Control System Programming Information ............................................................. 2-10

CHAPTER 3 FUNCTIONAL DESCRIPTION

3.1 INTRODUCTION .............................................................................................. 3-1

3.2 MECHANICAL DESCRIPTION ....................................................................... 3-1

3.2.1 Overview ................................................................................................................... 3-1

3.2.2 Double-Wall Heat Transfer and Water Leakage ....................................................... 3-2

3.2.3 Principal Mechanical Components ............................................................................ 3-2

3.3 ELECTRONIC CONTROL SYSTEM ............................................................... 3-4

3.3.1 ECS Block Diagram .................................................................................................. 3-4

3.3.2 ECS Operational Summary........................................................................................ 3-5

3.3.3 Over-temperature Condition ...................................................................................... 3-5

3.3.4 Principal ECS Components ....................................................................................... 3-6

CHAPTER 4 ADJUSTMENT

4.1 INTRODUCTION .............................................................................................. 4-1

4.2 ADJUSTING THE ELECTRONIC CXT-E ACTUATOR ................................ 4-1

4.3 ADJUSTING THE ELECTRONIC CONTROL SYSTEM ............................... 4-2

4.3.1 Adjusting the Setpoint Temperature .......................................................................... 4-3

4.3.2 Adjusting the Over-temperature Alarm Limit ........................................................... 4-5

CHAPTER 5 OPERATION

5.1 INTRODUCTION .............................................................................................. 5-1

5.2 PRE-OPERATIONAL ........................................................................................ 5-1

5.3 STARTUP PROCEDURES ................................................................................ 5-1

5.4 SHUTTING DOWN AND DRAINING THE HEAT EXCHANGER ............... 5-3

HE-111 − CONTENTS

CHAPTER 6 SCHEDULED MAINTENANCE

6.1 INTRODUCTION .............................................................................................. 6-1

6.2 WEEKLY MAINTENANCE ............................................................................. 6-1

6.3 MONTHLY MAINTENANCE .......................................................................... 6-1

6.4 QUARTERLY MAINTENANCE ...................................................................... 6-2

6.4.1 First Three Months .................................................................................................... 6-2

6.4.2 Each Quarter .............................................................................................................. 6-2

6.5 SEMI-ANNUAL MAINTENANCE .................................................................. 6-3

6.6 ANNUAL MAINTENANCE ............................................................................. 6-3

CHAPTER 7 TROUBLESHOOTING

7.1 INTRODUCTION .............................................................................................. 7-1

7.2 TROUBLESHOOTING PROCEDURES ........................................................... 7-1

CHAPTER 8 CORRECTIVE MAINTENANCE

8.1 INTRODUCTION .................................................................................................8.1

8.2 CXT-E ELECTRONIC CONTROL VALVE ...................................................... 8-1

8.2.1 Valve Shaft Seal Retainer Replacement .................................................................... 8-7

8.2.2 Valve Disassembly .................................................................................................... 8-8

8.2.3 Valve Reassembly ................................................................................................... 8-11

8.2.4 Actuator Replacement ............................................................................................. 8-13

8.2.5 Linkage Assembly Replacement ............................................................................. 8-15

8.2.6 Recirculation Pump Replacement ............................................................................ 8-16

8.3 ELECTRONIC CONTROL SYSTEM ............................................................. 8-18

8.3.1 Replacing the Control Box Assembly ..................................................................... 8-18

8.3.2 Replacing the Temperature Contro ller .................................................................... 8-19

8.3.3 Replacing the Over-temperature Switch and Temperature Indicator ...................... 8-20

8.3.4 Replacing the DC Power Supply ............................................................................. 8-21

8.3.5 Replacing the DC Voltage Regulator ...................................................................... 8-21

8.4 RECOMMENDED SPARE PARTS ................................................................ 8-27

CHAPTER 9 DISASSEMBLY AND REASSEMBLY

9.1 INTRODUCTION 9-1

9.1.2 Tools Required .......................................................................................................... 9-1

9.2 CHECKING FOR A TUBING LEAK ............................................................... 9-1

9.3 REMOVING THE HEAT EXCHANGER SHELL ........................................... 9-1

9.4 REASSEMBLING THE HEAT EXCHANGER ................................................ 9-3

APPENDIX

A. CONTROL AND COMMUNICATION

A.1 TEMPERATURE CONTROLLER PROCEDURES ............................. A-2

A.2 MODBUS COMMUNICATION INFORMATION ............................... A-7

A.3 PROCESS AND DIAGNOSTIC ALARMS ........................................... A-8

B. WIRING DIAGRAMS

HE-111 − CONTENTS

B.1 DW-SERIES HEAT EXCHANGER WIRING DIAGRAMS ..................B-2

B.2 TERMINAL BLOCK CONNECTIONS ..................................................B-3

C. PIPING CONNECTIONS

C.1 SINGLE HEAT EXCHANGER ...............................................................C-2

C.2 PARALLEL HEAT EXCHANGERS.......................................................C-3

C.3 SINGLE HEAT EXCHANGER WITH AN ACCUMULATOR .............C-4

C.4 SINGLE HEAT EXCHANGER WITH A STRATIFIED ..............................

STORAGE TANK ....................................................................................C-5

C.5 MULTIPLE HEAT EXCHANGERS WITH A STRATIFIED

STORAGE TANK ....................................................................................C-6

HE-111 − SAFETY

SAFETY PRECAUTIONS

Personnel involved in the inst allation, operation and m aintenance of the SmartPlate Water Heater must, at all times, observe all safety regulations. The f ollowing Warnings are general and m ust be given the same attention as specific Warnings and Cautions appearing throughout this Instruction Manual.

WARNING

FLUIDS UNDER PRESSURE MAY CAUSE INJURY TO PERSONNEL OR DAMAGE TO EQUIPMENT WHEN RELEASED. BE SURE TO SHUT OFF ALL INCOMING AND OUTGOING WATER SHUTOFF VALVES. CAREFULLY DECREASE ALL TRAPPED PRESSURES TO ZERO BEFORE PERFORMING MAINTENANCE.

WARNING

ELECTRICAL VOLTAGES UP TO 240 VAC MAY BE USED IN THIS EQUIPMENT. DEATH ON CONTACT OR SERIOUS PERSONAL INJURY MAY RESULT IF EXPOSED CONNECTIONS ARE TOUCHED.

WARNING

CLOSE ALL SHUT-OFF VALVES AND CAREFULLY DECREASE TRAPPED PRESSURES TO ZERO BEFORE PERFORMING ANY MAINTENANCE TASKS. TAG THE UNIT “OUT OF SERVICE” WHILE PERFORMING MAINTENANCE TASKS.

1-1

CHAPTER 1 GENERAL INFORMATION

1.1 INTRODUCTION

AERCO’s DW-series heat exchangers provide potable hot water for commercial and institutional applications. These heat exchangers are available in steam-to-water configurations and are equipped with electronic controls. This manual addresses the steam-to-water double-wall heat exchanger with electronic controls.

The three steam-to-water DW heat exchangers available from AERCO include the:

• DW-24 with 24 square feet of heating surface

• DW-45 with 45 square feet of heating surface

• DW-68 with 68 square feet of heating surface

Figure 1-1 illustrates a typical AERCO DW-series heat exchanger.

Figure 1-1. DW-24 Heat Exchanger

This chapter provides a top-level mechanical overview of the DW-series heat exchanger (1.2), its electronic control s ystem (1.3) and the opt ions and accessories ava ilable from AERCO ( 1.4) for units in this series

1.2 MECHANICAL OVERVIEW

The AERCO double-wall steam-to-water heat exchanger is illustrated in Figure 1-2:

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1-2

AERCO

STEAM INPUT

CONDENSATE OUTPUT

SHELL ENCLOSING THE TUBE BUNDLE

COLD WATER INPUT

HOT WATER OUTPUT

CONTROL BOX

RECIRCULATION PIPING

RECIRULCATION PUMP

UPPER HEAD ASSEMBLY

CXT-E CONTROL VALVE

CXT-E ACTUATOR

LOWER HEAD ASSEMBLY

Figure 1-2. Mechanical Overview of the AERCO Double-Wall Steam-to-Water Heat

Exchanger

The DW steam-to-water heat exchanger includes the following principal mechanical parts and assemblies:

• Shell and upper/lower head assemblies

• Enclosed double-wall tube bundle and tubesheets

• Input/output connections for steam, condensate and h ot/c ol d water

• Control Valve

• Recirculation piping and pump

1.3 ELECTRONIC CONTROL SYSTEM

The Electronic Control S ystem (ECS; illustrated in Fig ure 1-3) includes the C ontrol Box components and associated temperature sensors and actuators. The ECS:

• Controls the temperature of the hot water output to within ±4°F of the Control Box setting under normal, diversified load conditions (load fluctuations of up to 25% of water heater capacity)

• Shuts down the heat exchanger when the maximum safe water temperature is exceeded

• Relays commands and alarms from/to the MODBUS Communication Option

The ECS and its components are described in Chapter 3.

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1-3

DHW

DUAL OUTLET

TEMP. SENSOR

OVER-TEMPERATURE

SOLENOID VALVE

CONTROL BOX

ASSEMBLY

CONSTANT RATE

RECIRCULATION

PUMP

FEED-FORWARD

MIXTURE TEMP.

SENSOR

CXT-E CONTROL

VALVE ACTUATOR

CONTROL

VALVE

Figure 1-3. Electronic Control System Components

1.4 OPTIONS AND ACCESSORIES

1.4.1 MODBUS Communication Option

The ECS can be ordered with th e MODBUS Communication Opt ion to enable the ECS to be externall y controlled by an Energy Management System, Building Automation System or computer (supplied by others).

1.4.2 Accessories

Accessories available for the DW-series steam-to-water heat exchangers equipped with the CXT-E Electronic Control Valve are listed in

Table 1. Re quired access ories ma y be supplied separatel y by AERCO if the y are not factory-ins talled on the heater.

The accessories required will depend on the specific application. Detailed installation instructions, including typical installation drawings are provided in Chapter 2 Installation. Please ensure that ALL mandatory items are available for installation.

If any of these items have been furnished by AERCO, the necessary drawings and/or instructions are included with the shipment.

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HE-111 − GENERAL INFORMATION

1-4

Supplied

I. DW-Series Heat Exchanger

Temperature Controller

Yes

Required

Pressure and Temperature Relief Valve

Yes

Required

including:

• Solenoid valve

• Water temperature sensor in heat

exchanger upper head

• Over-temperature indicating switch

required for the application

mounted on steam inlet connection

II. CXT-E Actuator and Valve

Required if a bypass line is used

Table 1. DW-Series Heat Exchanger and CXT-E Actuator/Valve Accessories

Description AERCO

Over-temperature Limit System,

Steam Flow Control Valve, sized as

Compound Steam Pressure Gauge,

Traps No Required

• Drip trap

• Valve trap

• Condensate trap

Vacuum Breaker Yes Required

Yes Required

Remarks

Upstream Shutoff Valve No Required Downstream Shutoff Valve No

Strainer and Blow-Off Valve No High Side Pressure Gauge No

Low Side Pressure Gauge, compoundtype for steam flow

• Suggested for ease of maintenance

•

Required Recommended for adjustment and

maintenance Recommended for adjustment and

maintenance.

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2-1

CHAPTER 2 INSTALLATION

2.1 INTRODUCTION

This chapter provides instructions for:

• Receiving the heat exchanger and installing it in a suitable location (2.2)

• Piping into the steam and water systems (2.3)

• Installing and connecting the Electronic Control System (2.4)

2.2 RECEIVING, UNPACKING AND INSTALLING

To prepare the heat exchanger for installation:

1. Carefully uncrate the heat exchanger.

2. Set the heat exchanger upright us in g a bl ock and tackle or hoist attac he d to t he lifting lugs (eye-bolts) on the top head.

CAUTION

ALWAYS USE THE LIFTING LUGS to lift and/or move the heat exchanger.

3. To simplify in-place maintenance, install the heat exchanger in a location having the following clearances:

a. Horizontal clearance: At least two (2) feet all-around b. Headroom: At least six (6) feet measured upward from the top of the upper shell flange. The dimensions of the AERCO Model DW-heat exchangers are presented in Figures 2-1 through 2-3.

4. Secure the heat exchanger in place, pref erabl y, by att aching it to the f loor. If you use pip ing to secur e the heat exchanger in position, be sure to include ample provision for pipe expansion.

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2-2

WIRE TO COMPONENTS

M A N

R U N

H O L D

83.33

(211.66)

32.18

(81.74)

17.26

(43.84)

COMPOUND PRESSURE GAUGE (S/W)

STEAM INLET

15.44

(39.22)

12.44

(31.60)

13.00

(33.02)

16.00

(40.64)

FOUR .75 (1.91)Ø HOLES

1.63

(4.14)

OUTLET TEMP. SENSOR

1/2" (1.27) WATER SOLENOID

2.50" NPT

CONDENSATE

OUTLET

FLOAT & THERMOSTATIC

STEAM TRAP (BY OTHERS)

3/4" PLUGGED

DRAIN

TEMPERATURE

CONTROLLER

1.50 (3.81) THICK INSULATION

CXT-E VALVE

VACUUM BREAKER (STEAM TO WATER)

8.11

(20.60)

3.80

(9.65)

1.75

(4.45)

30.50

(77.47)

18.66

(47.40)

3" NPT COLD

WATER INLET

3" NPT HOT

WATER OUTLET

115 VAC, 2A, 60 HZ POWER SUPPLY REQUIRED

81.20

(206.25)

9.00

(22.86)

DOUBLE WALL TUBE LEAK DETECTION PORT (NOT TO BE PLUGGED)

RECIRC

PUMP

14.90

(37.85)

P&T RELIEF VALVE

1/2" NPT VALVE

TRAP CONNECTION

(STEAM TO WATER ONLY)

2.28

(5.79)

Figure 2-1. AERCO Model DW-24 Heat Exchanger Dimensions

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HE-111 − INSTALLATION

2-3

AERCO

96.20

(244.35)

25.11

(63.78)

11.52

(29.26)

5.22

(13.26)

39.87

(101.27)

VACUUM BREAKER (STEAM TO WATER)

COMPOUND PRESSURE GAUGE (SW)

CXT-E VALVE

STEAM INLET

3/4" PLUGGED

DRAIN

TEMPERATURE

CONTROLLER

P&T RELIEF VALVE

1/2" (1.27) WATER SOLENOID

1.00 (2.54)

1/2" NPT VALVE

TRAP CONNECTION

(STEAM TO WATER ONLY)

FLOAT &

THERMOCSTATIC

STEAM TRAP (BY OTHERS)

4" 150# FLG

CONDENSATE

OUTLET

1.50 (3.81) THICK INSULATION

FOUR .75 (1.91)Ø HOLES

OUTLET TEMP.

SENSOR

16.50

(41.91)

19.50

(49.53)

21.00

(53.34)

24.00

(60.96)

2.50

(6.35)

2.88

(7.32)

115 VAC, 2A, 60 HZ POWER SUPPLY REQUIRED

DOUBLE WALL TUBE

LEAK DETECTION PORT

(NOT TO BE PLUGGED)

27.24

(69.19)

15.97

(40.56)

14.00

(35.56)

36.00

(91.44)

RECIRC

PUMP

WIRE TO COMPONENTS

3" NPT HOT

WATER OUTLET

89.00

(226.06)

3" NPT

COLD

WATER

INLET

Rev B Mar 2013

Figure 2-2. AERCO Model DW-45 Heat Exchanger Dimensions

HE-111 − INSTALLATION

2-4

COMPONENTS

WIRE TO

AERCO

92.70

(235.46)

25.04

(63.60)

10.11

(25.68)

5.75

(14.60)

COMPOUND PRESSURE GAUGE (S/W)

STEAM INLET

CXT-E VALVE

VACUUM BREAKER (STEAM TO WATER)

39.87

(101.27)

3/4" PLUGGED

DRAIN

1.50" (3.81) THICK INSULATION

TEMPERATURE

CONTROLLER

FLOAT &

THERMOSTATIC

STEAM TRAP (BY OTHERS)

10.00 (25.40)

1.00 (2.54)

1/2" (1.27) WATER SOLENOID

P&T RELIEF VALVE

1/2" NPT VALVE TRAP CONNECTION (STEAM TO WATER ONLY)

24.00

(60.96)

21.00

(53.34)

19.50

(49.53)

16.50

(41.91)

OUTLET TEMP.

SENSOR

3.50

(8.89)

3.50

(8.89)

FOUR .75 (1.91)Ø HOLES

87.56

(222.40)

27.16

(68.99)

16.50

(41.91)

36.00

(91.44)

115 VAC, 2A, 60 HZ ELECTRICAL POWER SUPPLY REQUIRED

14.00

(35.56)

3" NPT

COLD WATER

INLET

3" NPT

HOT WATER

OUTLET

DOUBLE WALL TUBE

LEAK DETECTION PORT

4" 150# FLG.

CONDENSATE

OUTLET

RECIRC

PUMP

Figure 2-3. AERCO Model DW-68 Heat Exchanger Dimensions

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HE-111 − INSTALLATION

2-5

TO HEATER

FROM

STEAM

SOURCE

UPSTREAM

SHUTOFF

VALVE

LOW SIDE

PRESSURE

GAUGE

CXT-E ACTUATOR

HIGH SIDE

PRESSURE

GAUGE

DOWNSTREAM SHUTOFF VALVE

PIPE UNIONS (NOT REQUIRED WHEN VALVE IS FLANGED)

STRAINER

TO TRAP &

CONDENSATE

DRAIN

BLOW-OFF VALVE

NOTE: KEEP PIPING AS SHORT AS POSSIBLE)

CXT-E CONTROL VALVE

2.3 MAKING THE PIPING CONNECTIONS

Figure 2-4 illustrates the recommended CXT-E Control Valve installation for steam flow.

Figure 2-4. Recommended Control Valve, CXT-E Installation for Steam Flow

1. Install the CXT-E Control Valve with the Actuator linkage in the vertical, upright position, as shown.

2. For maintenance purposes, insta ll pipe unions with threaded e nds t o sim plif y remova l from the s team line.

3. Blow out all pipe lines to rem ove dirt chips, scale or other for eign matter wh ich could a dversel y affect Control Valve (“Valve”) operation when in service.

4. Install an in-line strainer upstr eam of the Valve (as illus trated on the left si de of Figur e 2-4) to protec t against foreign matter entering the Valve during service operation.

5. Ensure that the steam line is properl y trapped to prevent accumulation of condens ate ahead of the Valve.

6. Install metal-seated, gate-t ype s hutof f va lves ups tre a m and downstream of the Val ve so t hat it ca n be readily removed from the line for maintenance.

7. Install pressure gauges on both sides of the Control Valve, as shown in Figure 2-4.

8. The high-side pressure gauge is provided for adj ustment and maintenance purposes . The low-side pressure gauge is intended to ensure that the cor rec t pr ess ur e is available to monitor the operation of the temperature regulator valve. The low-side pressure gauge measures the pressure of the steam`.

CAUTION

When installing the Valve, DO NOT us e the Ac tuator linkage frame at the top of the Valve body for leverage. Use pipe wrenches on the inlet and outlet hex of the Valve body.

9. Install the Valve so that the arrow on the Valve body points in the direction of steam flow.

10. After the Valve has been installed in the steam or hot water line, ensure that al l piping connections are secure and leak-tight.

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HE-111 − INSTALLATION

2-6

The AERCO recommended heat exchanger and Control Valve piping arrangements for single and parallel heat exchanger installations are presented in Appendix C.

11. For best heat exchanger performance, OBSERVE THE FOLLOWING VERY CAREFULLY when installing the heat exchanger piping:

a. Do not use cement or red lead when assembling pipe joints. b. For heat exchanger connec tion types, sizes, and exact locat ions, see Figure 2-1, Figure 2-2 or

Figure 2-3.

c. All piping to the heat exch anger top head should be provided with u nions or flanges LOCATED

BEYOND THE OU TSIDE DIAMET ER OF THE HEAT EXCHANGER H EAD to perm it removal of the head and shell for in-place maintenance.

d. Include all of the stop va lves, check valves, s team traps, strai ners and other el ements shown in

Appendix C, or as specified separately by AERCO.

e. If the heat exchanger is furnished with the Control Valv e not connected as sho wn in Figure 2-1,

Figure 2-2, or Figure 2-3, mak e the piping bet ween t he Contro l Valve a nd the h eat exchang er as short as possible, with sufficient unions or flanges included to allow easy Valve removal.

f. Reductions from a pipe to a smaller size connection at the heat exchanger or Control Valve

should be made directl y at the heat exchanger or Valve connection. Expansions f rom a pipe to a larger size connectio n at the hea t exchan ger or Contr ol Valve should be m ade as far as pr actical from the heat exchanger or Valve connection.

g. The condensate return p iping must be arranged to p ermit condensate to drain freely by gravity

from the heat exchanger connection. If condensate drain by gravity is not feasible, you may substitute a pumping steam trap. Refer to the trap manufacturer’s instructions for sizing and installation procedures.

CAUTION

Failure to provide proper condensate drainage can result in improper operation of the heat exchanger and/or damage to the heat exchanger condensate drainage system.

h. All drain discharges ― relief valve, over-temperature solenoid valve and heat exchanger shell

drain ― should be piped directly to a convenient floor drain.

IMPORTANT

Before making final p iping connections to and fr om the heat exchanger and Control Valve, blow out all piping thoroughly.

2.4 INSTALLING THE CXT-E ELECTRONIC CONTROL SYSTEM

The Control Box and all other Electronic Control System (ECS) components are installed on the heat exchanger assembly before it is shipped from the factory, so that the ECS installation consists of connecting AC power t o the Control Box and making the internal power and control connec tions to the CXT-E Control Valve. Ho wever, if your ECS was ordered with th e MODBUS Com munication option, you are required to m ake several a dditional c onnections (startin g with step 8, belo w) to enabl e the ECS to be controlled by an external Energy Management System (EMS), Building Automation System (BAS) or computer.

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HE-111 − INSTALLATION

2-7

TEMP CONTROLLER

HOLD

RUN

AUTO

MAN

2408

OVER TEMP SWITCH

PANEL DOOR

CAPTIVE SCREW

2.4.1 Accessing the Control Box Interior

NOTE

After installing the Contro l Box, you can inst all a lock (not supp lied) on its f ront do or to prevent unauthorized access to ECS settings.

1. Loosen the captive screw on the Control Box (Figure 2-5) front cover and open the hinged panel door.

Figure 2-5. ECS Control Panel Front View

2. Loosen the captive scr ew at the top of the recessed panel (Figure 2-6). Swing down t he recessed panel to access Terminal Block TB-2 on the bottom interior surface of the Control Box (see Figure 2-7).

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2-8

PANEL CAPTIVE

CONTROL BOX - INTERIOR BOTTOM VIEW

REAR

TB-2

LINE

NEUTRAL

GROUND

100

101

102

GND

FRONT

VOLTAGE

REGULATOR

TERMINAL

BLOCK TB-2

EXTERNAL POWER WIRING

(120 VAC)

SCREW

2408

OP 1

OP 2

SP2

REM

AUTO

RUN

MAN HOLD

TEMP CONTROLLER

Figure 2-6. Recessed Panel Behind Control Box Door

2.4.2 Connecting AC Power to the Control Box

PT.NO.

SET

OVER TEMP SWITCH

PT.NO.

3. Feed the external 120 VAC power leads thr ough the cutout labele d “POWER IN” on the rig ht side of the Control Box.

4. Connect the LINE, NEUTRAL and GROUND leads to the TB-2 terminals shown in Figure 2-7.

Figure 2-7. ECS Control Box AC Power Connections

2.4.3 Wiring the CXT-E Actuator

5. Connect the Control Box cable labeled ACTUATOR to the 3-pin connector plug on the CXT-E Actuator.

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2-9

2408 TEMP. CONTROLLER

COMPUTER CONTROL CABLE

RS232 9-PIN

RS232 25-PIN

RS485

SIGNAL NAME

TERMINAL

SIGNAL NAME

PIN NO.

GROUND

GROUND 5 7

GROUND

RECEIVE

TRANSMIT

3 2 A(-)

TRANSMIT

RECEIVE 2 3

B(+)

2.4.4 Verifying Pre-wired Connections

6. Check to ensure that al l pre-wired cable harn ess connec tors an d w ire le ads bet ween the C ontro l Box and the following ECS components are secure:

• Recirculation Pump

• Over-Temperature Solenoid

• Outlet Dual Temperature Sensor

• Mixed Temperature Sensor

7. If the ECS was ordered with the MO DBUS C omm unication Optio n, proc eed to step 8. Otherwise, the ECS installation is complete.

2.4.5 Wiring the Temperature Controller to the MODBUS Control System

Step 8, below, applies to the Euro therm, Mode 2408 Tem perature Controller equipped with a MODBUS communication board and connected to an Energy Management System (EMS), Building Automation System (BAS) or computer. The type of communication port (RS232-9, RS232-25, or RS485) mounted on the EMS, BAS or com puter determines the relevant s ignal leads (Ground, Recei ve and Transmit) in the control cable that you connect to the MODBUS dev ice and the Temperature Contr oller, as described in Table 2-1.

NOTE

If required, the procedure for adding a communication board to the Temperature Controller is provided in Appendix A

Table 2-1. MODBUS Communication Signal Connections

8. Refer to Table 2-1, Figure 2-8 and/or the ECS wiring dia gram in Appendix B to wire the Ground (HD) , Receive (HE) and Transm it (HF) terminals of the T emperature Controller to the RS23 2-9, RS232-25 or RS485 connector on the EMS, BAS or computer.

Examples of cable types suitable for this purpose are: Belden 9841, 8761, 3105A, or equivalent. Ensure that the RS232 or RS485 cable connections do not exceed the following lengths:

• RS232 Cable: 50 feet, maximum

• RS485 Cable: 4,000 feet, maximum

NOTE

For best results, DO NO T run MODBU S com m unication wiring in t he sam e c onduit as power wiring which can couple excessive noise and/or hum into the MODBUS lines.

Rev B Mar 2013

HE-111 − INSTALLATION

2-10

2A 2B

HE HF

2D 3A

JB JC

LA LB LC AA AB AC

VI V+ V-

Input 1

2408 CONTROLLER

L N

Input 2

MODBUS CONTROL DEVICE

SHIELDED TWISTED PAIR

Figure 2-8. Cable Connections for Eurotherm 2408 Temperature Controller

2.4.6 Control System Programming Information

Appendix A lists the MOD BUS data addresses for the 2408 C ontroller. The procedures for changing the Controller address is also provided in Appendix A. Also included are references to the manufacturer’s handbooks covering the Temperature Controller communication option.

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3-1

CHAPTER 3 FUNCTIONAL DESCRIPTION

COLD WATER INPUT

HOT WATER OUTPUT

RECIRULCATION PUMP

3.1 INTRODUCTION

The AERCO DW-series steam-to-water heat exchangers incorporate double–wall heat tubes, in which steam circulating in a bundle of imm ersed double-wall prim ary tubes heats the s ervice water in the he at exchanger’s shell. The following Mechanical Description (3.2) briefly discusses how double-wall heat tubes work and describes each of the principal steam-to-water heat exchanger components. The Mechanical Description is followed by a discussion of the Electronic Control System (3.3), which regulates the heat exchanger water tem perature and activat es alarm s and shutdown proce sses in the event s afety limits are exceeded.

3.2 MECHANICAL DESCRIPTION

3.2.1 Overview

Referring to Figure 3-1, c old service water enter ing the heat exchanger thr ough the Cold Water Input is dispersed evenly througho ut the heat exchanger shell. As the cold water flows upward, it is heated by steam circulating through the immersed tube bundle. The heated service water exits through the Hot Water Output connection in the upper head assembly.

UPPER HEAD ASSEMBLY

RECIRCULATION PIPING

UPPER TUBESHEET

LOWER TUBESHEET

CONTROL BOX

SHELL

LOWER HEAD ASSEMBLY

CONDENSATE OUTPUT

AERCO

CXT-E ACTUATOR

CXT-E CONTROL VALVE

STEAM INPUT

Figure 3-1. AERCO Steam-to-Water Double-Wall Heat Exchanger

The heating steam enters through the CXT-E Control Valve at the bottom of the heat exchanger assembly and flows thr ough the inner tubes of the double-wall tube bund le. The flowing steam transfers its heat to the service water contained within the shell, condenses and exits through the Condensate Output connection.

The flow rate of the heated water varies according to the demand for hot water. The flow rate of the steam is regulated by the Tem perature Contr oller in th e Control Box so as to maintain the tem perature of

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HE–111− FUNCTIONAL DESCRIPTION

3-2

STEAM

PRIMARY TUBE

INNER WALL

HEATED SHELL-SIDE

SERVICE WATER

PRIMARY TUBE

OUTER WALL

AIR SPACE

the delivered hot water t o within ±4 °F of the Contr ol Box sett ing, un der nor m al, divers ified lo ad con ditions (load fluctuations of up to 25% of water heater capacity).

3.2.2 Double-Wall Heat Transfer and Water Leakage

As illustrated in Figur e 3-2, the heat exchanger’s prim ary tubes incorporate doubl e-wall construction in which the inner and outer tube walls are separated b y air space. T he steam flows within the double-wall primary tubes’ inner walls. Any condensate leaking outward through the inner walls is trapped within vented air space bet ween the inner an d outer tube wal ls. A ny serv ice water th at l eaks inward t hrough t he outer tube walls is sim ilarly contained within th e air space. T he accumulated leakage water is conducted along these air spaces, collected in the bottom head (see 3.2.3.2) and discharged through an atmospherically vented leak detection port. This construction effectively provides double protection against primary steam or condensate leaking into the service water, or vice versa. However, it is not unusual for moistur e to appear at the leak detection port at in itial heat exchanger start-up, even when there are no tube leaks . This moisture results from water condens ing during the manufacturing proc ess and being expelled when the system is initially operated.

Figure 3-2. Segment of a Double-Wall Primary Tube

3.2.3 Principal Mechanical Components

The AERCO DW -series heat exchanger cons ists of the following pri ncipal mechanical com ponents (see Figure 3-3):

• Shell and heads (3.2.3.1)

• Double-wall U-bend tube bundle and tubesheet (3.2.3.2)

• Recirculation pipe and pump (3.2.3.3)

• Electronic CXT-E Control Valve (3.2.3.4)

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HE–111 − FUNCTIONAL DESCRIPTION

3-3

COMPOUND PRESSURE GAUGE

STEAM INPUT

SOLENOID VALVE

CONDENSATE OUT

PLUGGED DRAIN

TEMPERATURE CONTROLLER

CXT-E CONTROL VALVE

VACUUM BREAKER

PRESSURE AND TEMPERATURE RELIEF VALVE

CXT-E ACTUATOR

CONTROL BOX

SHELL

COLD WATER INPUT

HOT WATER OUTPUT

LEAK DETECTION PORT

RECIRCULATION PUMP

RECIRCULATION PIPING

OUTLET MANIFOLD

LOWER SHELL FLANGE

UPPER SHELL FLANGE

UPPER HEAD ASSEMBLY

LOWER HEAD ASSEMBLY

Figure 3-3. AERCO Double-Wall Heat Exchanger, Model DW-24

3.2.3.1 Shell and Heads

The heat exchanger body incorporates a stainless steel shell, bronze upper head and navy brass tubesheets, forming a pressure vessel that conforms to ASME standards. The heat exchanger body encloses the tube bundle and tubesheets.

3.2.3.2 Double-Wall U-Tube Bundle and Tubesheets

The double-wall U-bend copper tubes that conduct steam through the heater shell conform to BOCA (National Plumbing Co de), IAPMO (Unif orm Plum bing Code) and NAPHC C (National Sta ndard Plum bing Code), the three nat ional st andards that addr es s doubl e-w all cons tructi on. The o ut er wall of each doubl ewall tube is brazed to the upper tubesheet, and the inner wall is brazed to the navy brass lower tubesheet. Any tube leak age from the air spaces between the inner and outer walls of the double-wall tubes accumulates in t he space between t he bottom shell flang es which make up the bottom head. The accumulated leakage water is discharged through the leak detection port.

3.2.3.3 Recirculation Pipe and Pump

Referring to Figure 3-3, th e recirculation pipe and constant-rate r ecirculation pump deliver a continuous sample of the heated o utput water to a 1½-inch pipe junction with the Cold W ater Input pipe to reg ulate steam flow at the Steam Input (see 3.3.2).

3.2.3.4 CXT-E Control Val ve

The CXT-E Control Valve regulates the flow rate of steam into the heat exchanger in response to positioning control signaling from the Temperature Controller (see 3.3.2). The CXT-E Control Valve consists of a valve body and linkage to the CXT-E Actuator. The CXT-E Actuator is discussed in 3.3.4.5.

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HE–111− FUNCTIONAL DESCRIPTION

3-4

DHW

DUAL OUTLET

TEMP. SENSOR

OVER-TEMPERATURE

SOLENOID VALVE

CONTROL BOX

ASSEMBLY

CONSTANT FLOW

RECIRCULATION

PUMP

FEED-FORWARD

MIXTURE TEMP.

SENSOR

CXT-E ACTUATOR

CXT-E CONTROL

VALVE

3.3 ELECTRONIC CONTROL SYSTEM

The Electronic Control S ystem consists of the interna l Control Box components and a number of sensor and safety devices distributed throughout the heat exchanger assembly (see Figure 3-4).

3.3.1 ECS Block Diagram

A simplified block diagram of the ECS is presented in Figure 3-5.

Figure 3-4. Electronic Control System Components

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HE–111 − FUNCTIONAL DESCRIPTION

3-5

Figure 3-5. ECS Simplified Block Diagram

3.3.2 ECS Operational Summary

The ECS adjusts the flow rate of steam into the heat exchanger in response to:

• The water temperature at the Hot Water Output (at A)

• The water temperature of the sampled Hot Water Output mixed with the Cold Water Input (at B)

Changes in hot water dem and vary the flow rate of service water through t he heat exchanger, requirin g compensating adjustments of the steam flow rate to maintain the service water temperature. To determine what steam flow rate adjustments are required, the Temperature Controller m onitors (via the feed-forward signal) t he temperature of a continuous sam ple of output hot water mixed (at B) with th e cold water input. T he m ixture tem perature cha nges ac cording to the flo w rate of the incom ing cold water, which in turn depends on the hot water demand.

The Temperature Co ntroller calc ulation of the optimum steam flow rat e into the heat exchanger is based on a mathematical process known as the Proportional Integral D erivative (PID) algorithm , which accepts as inputs the measured outlet and inlet temperatures of the system.

3.3.3 Over-temperature Condition

At startup, the operator programs the maximum safe water temperature into the Control Box. During operation, the Temperature Controller monitors the Hot Water Output temperature to ensure that the programmed max imum s afe tem per atur e is not ex c ee ded. If it is, t h e T em per ature C ontro ll er opera tes th e Over-temperature Solenoid Valve (see 3.3.4.4) to relieve excessive temperature buildup in the heat exchanger.

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HE–111− FUNCTIONAL DESCRIPTION

3-6

TEMP CONTROLLER

HOLD

RUNAUTO

MAN

2408

PT.NO.

OVER TEMP SWITCH

PANEL DOOR

TEMPERATURE CONTROLLER

OVER-TEMPERATURE SWITCH

3.3.4 Principal ECS Components

3.3.4.1 Control Box Assembly

The Control Box Assembly houses the components that monitor heat exchanger temperatures and operate system controls. The Control Box is illustrated in Figure 3-6. The Control Box components include the Temperature Controller, Over-temperature Switch and dc Power Supply/Voltage Regulator (not shown).

Figure 3-6. Control Box Front View

Temperature Controller. The Temperature Controller processes data received from the temperature and flow se nsors. Using the PID alg orithm, the T emperature Controller c alculates the optimum steam flow rate to maintain the Hot W ater Output temperature within the programm ed range. The Temperature Controller translates the optimum flow rate into a 4-to-20 mA control signal to the CXT-E Control Valve Actuator to adjust the Control Valve opening.

Over-temperature Switch. The Over-temperature Switch compares the output hot water temperature to the progra mmed high temperatur e limit, typicall y 20°F above the heater setpo int. If the measured Hot Water Output temperature exc eeds the maxim um setting, the Over -temperature Switch sounds an a udible alarm and activates t he Over-temperature Solen oid Valve, causing the overheated water to be dumped from the heater shell. Simultaneously, the Over-temperature Switch cuts off dc power to the CXT -E Control Valve Actuator, shutt ing off the flow of steam into the heat exchanger.

DC Power Supply/Voltage Regulator. The dc power supply within the Control Box converts the 120 VAC primary power to 12 VDC and 24 VDC to operate the Control Box com ponents, Overtemperature Switch, Over-temperature Solenoid Valve and the CXT-E Actuator.

3.3.4.2 DHW Outlet Dual Temperature Sensor

The DHW outlet dual temperature sensor consists of dua l thermocouple sensing elements mounted in the top head. The DHW outlet dual tem perature sensor continuous ly monitors t he service water temper ature at the Hot Water Output and trans m its it sim ultaneously to bot h the T emperatur e Contro ller and the Ov er temperature Switch in the Control Box.

3.3.4.3 Feed-Forward Mixture Temperature Sensor

The feed-forward m ixture temperature sensor is ins talled in the Cold W ater Inlet nozzle to measure the mixture temperature of the combined input cold water and the recirculated sample of the Hot Water Output.

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HE–111 − FUNCTIONAL DESCRIPTION

3-7

3.3.4.4 Over-temperature Solenoid Valve

The Over-temperature Solenoid Valve is operated by the Over-temperature Switch in the Control Box. When the preset high temperature limit is exceeded at the Hot Water Output, The DHW Outlet Dual Temperature Sensor s ignals the Over-temperature Sw itch, energizing th e Solenoid Valve and relieving the temperature build-up in the heat exchanger.

3.3.4.5 Electronic CXT-E Control Valve Actuator

The Electronic CXT-E Actuator operates the CXT-E Control Valve, as discussed in 3.2.3.4. Control Valves are available in pipe sizes ranging from 1 inch to 4 inches. Figure 3-7 identifies the basic dimensions for each size Electronic CX T-E Control Valv e. The CXT-E Actua tor is identical for e ach size valve. The linkage assemblies used with each size valve body are nearly identical, except for minor differences in the shaft adapter stroke of the mechanical linkage.

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HE–111− FUNCTIONAL DESCRIPTION

3-8

13.375

6.60"

4.50"

VALVE SIZES (INCHES) Dimension 1.00 1.25 1.50 2.00 2.50 3.00 4.00

A 21.12 21.12 21.12 24.25 24.25 24.25 24.25 B 7.75 7.75 7.75 7.75 10.87 10.87 10.87 C 3.56 3.56 3.56 3.56 6.38 6.38 6.38 D 6.00 6.00 6.00 6.00 10.87 10.87 10.87

Figure 3-7. CXT-E Control Valve and Actuator

Rev B Mar 2013

AC-105 INSTRUCTIONS - ECS & CXT-E

TEMP CONTROLLER

HOLD

RUN

AUTO

MAN

2408

PT.NO.

OVER TEMP SWITCH

PANEL DOOR

OVER-TEMP SWITCH

TEMPERATURE

CONTROLLER

POWER SWITCH

[

SEE FIGURE 4-3

CHAPTER 4 ADJUSTMENT

4.1 INTRODUCTION

This chapter explains the procedures you use to adjust the CXT-E Control Valve (“Valve”), Electronic CXT-E Actuator (“Actuator”) and Electronic Control System (ECS). The ECS is factory adjusted to the setpoint temperature s pecified on the sales order, and the Actuator is factory adjus ted (auto-stroked) to ensure that it correctly operates the Valve from the fully-open to the fully-closed positions.

To the extent necessar y, perform all the procedures listed in 4.2 and 4.3 before placing the system into operation and after replacing the Valve or any ECS components.

CAUTION

BE SURE that all steam shutoff valves are fully closed before performing any of the following adjustment procedures.

4.2 ADJUSTING THE ELECTRONIC CXT-E ACTUATOR

The Actuator is self-calibrating for all size Valves. The Actuator is power ed b y 24 VDC and contro ll ed b y a linear 4-to-20 mA control signal, as follows:

• A 4 mA control signal input operates the Valve to the fully-closed position (Valve shaft down)

• A 20 mA signal strokes the Valve to the fully-open position (Valve shaft up).

When properly connected t o the ECS, applying po wer to the Control Box applies +24 VDC power to the Actuator. The power switch is located on the right side of the Control Box, as illustrated in Figure 4-2.

Figure 4-1. Contr ol Box – Front View

IMPORTANT

Perform this adjustm ent af ter three m onths of use and annual ly there after . Also, t his adjustment is mandatory each time the Actuator is replaced or when mechanical adjustments are m ade to the Valve or its linkage.

Rev B Mar 2013 4-1

AC-105 INSTRUCTIONS - ECS & CXT-E

1”

1.25” and 2.5”

1.5” and 3”

2” and 4”

neptronic

1 2 3

1 2

4 5

DIP SWITCHES (3)

(ALL IN UP POSITION)

AUTO-STROKE

(RESET) BUTTON

LED

TERMINALS

PC BOARD

COVER SET SCREW

ACTUATOR

Automatically adjust the Actuator as follows:

1. Referring to Figure 4-2, loosen the set screw on the Actuator cover.

2. Remove the Actuator cover to access the PC board containing the terminal connections, DIP switches, Auto-Stroke (Reset) Button and LED.

3. Referring to Figure 4-1, use the power s witch to tur n on th e Control Box and apply 24 VDC po wer to the Actuator. (On the terminal strip: pin 2 = +24 VDC, pin 1 = Common) .

The LED will light indicating that power is applied to the Control Box.

4. Wait approximately 10 seconds for the un it to perform its self-test. T he LED will blink f rom one to f our times, depending on the size of the Valve, as follows:

Blinks Valve Size

5. For full-strok e automatic adj ustment, press the Reset button. T he LED will lig ht and the Actuator will rotate in both directions to find its open and closed Valve position stops.

6. When the autom atic adjustm ent is complete, the LED will b link f rom one to four tim es, depending on the size of the valves, as described in step 4, above.

7. Turn the Control Box power off to disconnect power to the Actuator.

8. Replace the Actuator cover and tighten the set screw.

4-2 Rev B Mar 2013

Figure 4-2. Actuator Adjustment

AC-105 INSTRUCTIONS - ECS & CXT-E

AUTO

RUN

MAN HOLD

OP 1

OP 2

SP2

REM

2408

UPPER DISPLAY (DISPLAY HOT WATER OUTLET TEMPERATURE)

AUTO SETPOINT MAN VALVE % OPEN

AUTO/MAN MODE INDICATORS

AUTO/MAN PUSHBUTTON

OP1 INDICATOR

ARROW BUTTONS

LOWER DISPLAY

MODE

DISPLAYS

4.3 ADJUSTING THE ELECTRONIC CONTROL SYSTEM

The ECS is factory set b y AERCO t o the setpoint temperature spec ified on th e sales order. N ormall y, the over-temperature alar m limit is set 20°F abo ve the specified set point. If no setpoint or o ver-temperature alarm lim it is specified, the ECS is set to the factory default values of 140 °F (setpoint) and 160 °F (overtemperature alarm limit).

To change the setpoint and over -temper ature alarm lim its, use the controls provided on the T emperatur e Controller and the Over -temperature Switch. These controls are visible thro ugh t he Control Box f r ont door window and can be accessed by opening the panel door (Figure 4-1).

4.3.1 Adjusting the Setpoint Temperature

Figure 4-3 illustrates and Table 4-1 describes the Temperature Controller controls and indicators. Use these controls/indicators to adjust the setpoint temperature as follows:

1. Turn the Control Box power switch on and open the Control Box door.

2. Wait approximately 3 seco nds while the Tem perature Controller performs its self-test. When the test is completed, the upper display will indicate the current heat exchanger Hot Water Output temperature, and the lower display will indicate the setpoint temperature stored in memory (default = 140°F), as illustra ted in Figure 4-3.

3. Ensure that the Temperature Contr oller is s et to the A UT O(m atic ) mode and the AUTO indicat or is lit. If the MAN(ual) indicat or is lit, pr ess the AUTO/MAN pushbutt on to toggle th e mode sett ing. I ndicator OP1 should also be lit.

4. Press the ▲ or ▼ arrow buttons, as necessary, to change the disp lay to the desired value.

5. Two seconds after the ▲ or ▼ arrow button is released, the display will blink to indicate that the Temperature Controller has accepted and stored the displayed value.

Figure 4-3. Temperature Controller

Rev B Mar 2013 4-3

AC-105 INSTRUCTIONS - ECS & CXT-E

INDICATOR

Output 1 Indicator

OP1 lights when a 4-to-20 mA signal is supplied to the OP2

Output 2 Indicator

Not used for the ECS application

SP2

Setpoint 2 Indicator

Not used for the ECS application

active.

AUTO

MAN

reset to 0%.

RUN

HOLD

Scroll Button

Press the Scroll button to select a new parameter in a list

Down Button

Press the Down button to decrease the value shown in

Table 4-1. Temperature Controller Operating Controls, Indicators and Displays

CONTROL /

OP1

REM

MEANING FUNCTION

Actuator, or when the valve position is above 0%.

Remote Setpoint Indicator

Auto/Manual Button and Indicators

Run/Hold Button and Indicators

REM lights when the ECS is set up to be controlled by a Remote (MODBUS) signal. REM will flash when MODBUS communication is

Pressing the button toggles the Controller between the automatic (AUTO) and manual (MAN) modes.

• AUTO lights when in the automatic mode.

• MAN lights when in the manual mode.

When entering the MAN mode, the Valve position is

Not used for ECS application

Page Button Press the Page button to select a new list of

parameters

the lower display

Up Button Press the UP button to increase the value shown in the

lower displa y

4.3.2 Adjusting the Over-Temperature Alarm Limit

Adjust the over-temperature alarm limit setting using the controls and displays illustrated in Figure 4-4 and described in Table 4-2. Adjust the over-temperature alarm limit as follows:

OVER-TEMPERATURE ALARM LIMIT ADJUSTMENT

The over-temperature alarm limit setting is adjusted using the controls and display on the OverTemperature Switch. The controls and display are illustrated and described in Figure 4-4 and Table 4-2. If necessary, over-temperature alarm limit adjustment is accomplished as follows:

1. With the Control Box door open, set the ON/OFF POWER switch on the right side to the ON position.

2. Press the SET button on the Over-Temperature Switch. SP will appear in the display.

3. Press the SET button again. The current over-temperature limit value stored in memory will be displayed (default = 160°F).

4-4 Rev B Mar 2013

AC-105 INSTRUCTIONS - ECS & CXT-E

INDICATOR

MEANING FUNCTION

LED Display

TEMP status

Displays current water temperature or setpoint.

RST

RESET Button

Resets the unit after an alarm condition.

UP Button

Increases the displayed temperature.

DOWN Button

Decreases the displayed temperature.

SET

SET Button

Used to access and store parameters in the unit.

4. If the display does not sh ow the desired over-temperature alarm setting, press the ▲ or ▼ arrow button to change the display to the desired temperature setting.

5. Once the desired over-temperature alarm setting is displayed, press the SET button to store the setting in memory.

6. To exit the programming mode, press the SET and ▼ buttons simultaneously, or simply wait one minute.

7. Once the programming mode has been exited, the display will show the current outlet water temperature of the Heater.

Figure 4-4. Over-Temperature Switch

Table 4-2. Over-Temperature Switch Controls and Indicators

CONTROL or

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4-6

This page intentionally left blank.

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5-1

CHAPTER 5 OPERATION

5.1 INTRODUCTION

This chapter provides instructions for:

• Preparing your heat exchanger and Electronic Control System (ECS) for operation (5.2)

• Turning on the heat exchanger and setting it to run automatically (5.3)

• Shutting down and draining the heat exchanger (5.4)

5.2 PRE-OPERATIONAL

1. Refer to Chapter 2 Installation and verify that:

a.Electrical power is properly connected to the ECS and the CXT-E Control Valve. b.All piping connections have been made according to recommended configurations. c. All connecting piping has been cleaned (blown) out.

2. Refer to Chapter 4 Adjustments and ver ify that the T em perature Control ler setpo int (4.3.1) and Overtemperature Switch alarm limit (4.3.2) have been set properly.

5.3 STARTUP PROCEDURES

1. Referring to Figure 5-1, press the power switch on the r ight side of the C ontrol Box to appl y power to both the Electronic Control System (ECS) and the CXT-E Control Valve. When power is initially applied, the Temperature Controller automatically performs a self-test sequence for approximately three seconds.

2. When the self-test is complete, the Temperature Controller will show the present hot water outlet temperature in the upper display and the setpoint temperature in the lower display.

3. Set the temperatures to the desired setpoints on the Over-temperature switch and the Eurotherm.

4. Set the Eurotherm into the Man mode and set the Valve position to 0%. If the temperature in the heater increases, see Chapter 7 Troubleshooting.

5. Open the stop valve in the C old Water Input line and h old t he relief valve in t he heat exchanger upper head assembly open to enable air to escape (to avoid an air poc ket build-up which coul d prevent the heat exchanger from f illing with water ) . When water flo ws out of t he relief valve, the heat exchanger is full.

6. Open an y stop valves in th e building or proc ess recirculat ion system , if such a s ystem is inc luded in the Heater installation.

7. Open the sto p valve in t he Hot W ater Output l ine. Open hot water fauc ets or va lves in the building or process to ensure a flow of water through the heat exchanger.

8. Slowly open all stop valves in the Steam Input and Condensate Output lines. If double block and bleed valving is used, make sure that the drain (bleed) valve is closed tight.

IMPORTANT

To prevent a possible over-temperature condition during initial start-up, be sure to perform the following steps in the order specified:

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HE-111 − OPERATION

5-2

TEMP CONTROLLER

HOLD

RUNAUTO

MAN

2408

PT.NO.

OVER TEMP SWITCH

PANEL DOOR

OVER-TEMP SWITCH

TEMPERATURE

CONTROLLER

POWER SWITCH

[

WATER TEMPERATURE AT

HOT WATER OUTLET

SETPOINT TEMPERATURE

AUTO

RUN

MAN HOLD

OP 1

OP 2

SP2

REM

2408

UPPER DISPLAY

LOWER DISPLAY AUTO/MAN MODE INDICATORS

AUTO/MAN PUSHBUTTON

OP1 INDICATOR

ARROW BUTTONS

Figure 5-1. Contr ol Box

9. Referring to Figure 5-2, press the AUTO/MAN pushbutton to toggle the AUTO/MAN display to the

10. The upper display will continue t o show the cur rent heat ex chan ger out let w ater temperature, and the

11. Using the ▲ arrow button, set the CXT-E Control Valve to the 10% position and monitor the heat

12. Continue to open the valve further in 5% increments until the Hot Water Output temperature begins to

13. When the Hot Water O utput water temper ature has increased to with in 20°F of the desired setp oint,

Rev B Mar 2013

MAN (Manual) mode. The MAN indicat or will light.

Figure 5-2. Temperature Controller

lower display will show the position of the CXT-E Control Valve Actuator in %. When the Manual mode is initially selected, the lower display will show 0%, indicating that the Control Valve is fully closed.

exchanger Hot Water Output water temperature.

increase at a moderate rate.

press the AUTO/MAN button to set the Temperature Controller to the AUTO mode. The AUTO indicator will lig ht and the MAN ind icator will go off. When the T emperature C ontroller is in the AUTO

HE-111 − OPERATION

5-3

mode, the upper display will continue to show the heat exchanger Hot Water Output water temperature, and the lower display will show the selected setpoint temperature.

14. In the AUTO mode, the ECS will stabilize at th e selected setpoint tem perature. When stabilized, t he ECS is set for unattended operation and no further operator intervention is required.

15. Close the Hot Water faucets or valves that were opened in step 7.

5.4 SHUTTING DOWN AND DRAINING THE HEAT EXCHANGER

To shut down the heat exchanger:

1. Set the Eurotherm to the MAN(ual) in the 0% Valve position.

2. Close all stop valves in the Steam Input and Condensate Output lines.

3. IN THIS ORDER, close the stop valves in the:

a. Hot Water Output line b. Recirculation line c. Cold Water Input line When the heat exchange has been shut down accor ding to steps 1 and 2, drain the heat exchanger as

follows:

4. CAREFULLY open the relief valve in the heat excha nger upper head assembly to r elieve pres sure in the heat exchanger shell. If water continu es to flow from the relief valve, one of the cold water stop valves is either leaking or is not shut tightly. Stop the flow from the relief valve and proceed.

5. Holding the relief valve open (to prevent creating a vacuum in the she ll), open the plugged drain at the bottom of the heater exchanger shell and drain the heat exchanger completely.

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6-1

CHAPTER 6 SCHEDULED MAINTENANCE

INDICATOR PLATE

VALVE TOP

PACKING

NUT

P/O LINKAGE

ASSEMBLY

LOWER

SHAFT

6.1 INTRODUCTION

This chapter lists the preventive maintenance procedures recommended for the heat exchanger and Electronic Control System (ECS). These recommendations include procedures to be performed each week (6.2), month (6.3), quarter (6.4), six-month interval (6.5) and year (6.6).

The recommended preventive maintenance schedule is summarized in Table 6-1 at the end of this chapter.

6.2 WEEKLY MAINTENANCE

□ Tube Leaks

Check the leak detection tube once each we ek for evidence of leaks in th e heat exchanger tubes. MAKE CERTAIN T HAT THE DETECT ION TUBE NEVER GET S PLUGGED. If any flui d is escaping from the detection tube, shut do wn the he at ex c hang e r as out li ned i n Section 5.4 and see Section 9.2 to investigate the leak.

6.3 MONTHLY MAINTENANCE

□ Steam Strainer

After the first month of operation, cle an the strain er in the Steam Input line in ac cordance with the instructions furnished with the strainer.

□ CXT-E Control Valve

Check the CXT-E Control Valve (“Valve”) for leaks, as follows:

1. Referring to Figure 6-1, check the packing nut and Valve top for evidence of leakage.

Figure 6-1. Valve Shaft Seals

2. If there is leakage between the pac king nut and Valve top, tighten the packing nut unt il the leakage stops. DO NOT FORCE the packing nut.

Take care not to over -tighten t he packing n ut to avoid tr apping the va lve stem and slowing or stopping Valve motion.

CAUTION

3. If tightening the packing nut does not s top the leak, the pack ing nut and packing assembly m ust be replaced in accordance with the procedures specified in Sections 8.2.2 and 8.2.3.

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6.4 QUARTERLY MAINTENANCE

6.4.1 First Three Months

□ Accumulated Shell Solids

After the first three months of initial operation, drain the heat exchanger as follows:

1. Close all stop valves in the Steam Input and Condensate Output lines.

2. IN THIS ORDER, close the stop valves in the: a. Hot Water Output line b. Recirculation line c. Cold Water Input line

3. CAREFULLY open the relief valve in the upper he ad assem bly to relieve pressure in th e shell. If fluid continues to flow from the relief valve, one of the Cold Water Input stop valves is either leaking or is not completely shut off. Securely close all Cold Water Input stop va lves until there is no mor e flow from the relief valve.

4. WITH THE RELIEF VALVE HELD OPEN (to prevent creating a vacuum in the shell), open the plugged drain at the bottom of the shell (see Figure 3-3), and drain the heat exchanger completely.

5. Examine the water being drained. a. If the am ount of solids in the water being drained ap pears to be heavy, set a schedule to drain

the heat exchanger every 3 months.

b. If the amount of solids appears to be light, set a schedule to drain the heat exchanger every 6

months.

c. Even if the am ount of s olids appears to be v er y light o r not at all, set a sche dule t o drai n the heat

exchanger at least once eac h year.

6. To refill the heat ex changer and place it b ack into operation, replace the drain plug an d perform the Pre-Operational and Operational steps l isted in Chapter 5.

6.4.2 Each Quarter

□ Valve Calibration

Refer to 4.2 and perform the CXT-E Actuator adjustment procedure as instructed.

□ Over-temperature Switch

Check the operation of the Over-temperature Switch as follows:

1. Refer to 4.3.2 and lower the over-temperature setting to approximately 5°F below the present setpoint, as shown in the lower display of the Temperature Controller.

2. Verify that an over-temperature alarm is generated and the following events occur: a. The CXT-E Control Valve closes. b. The Over-temperature Soleno id (located at top of heat exchan ger) opens and e xpels water fr om

the system.

c. The Over-temperature Switch generates an audible alarm.

3. When you have successfully completed the over-temperature alarm check, return the Overtemperature Switch to its original setting.

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6.5 SEMI-ANNUAL MAINTENANCE

□ Actuator

Refer to Section 4.2 and perform the Actuator adjustm ent procedure presented ther e. Verify that the Actuator strokes the Control Valve from the fully closed to the fully open position.

□ Temperature Controller

Check the Temperature Controller operation at least every 6 months. Make any necessary adjustments per Secti on 5. 3, steps 7 through 11.

□ Steam Strainer

Clean the strainer in the Steam Input line in accordance with the instructions furnished with the strainer.

6.6 ANNUAL MAINTENANCE

□ Temperature Sensors

AERCO recomm ends that you check the temperature sensors once a year to ensure that there is no scale build-up or clogging that may degrade system operation. To check the temperature sensors, proceed as follows:

HE-111 − SCHEDULED MAINTENANCE

1. Close the upstream and downstream water supply valves to the heat exchanger.

2. Check the DHW Outlet Temperature Sensor at the Hot Water Output port. If necessary, clean it using the following procedure:

a. Disconnect and remove the DHW Outlet Temperature Sensor (dual thermocouples). b. Inspect for evidence of scale buildup on the stainless steel sleeve. c. If necessary, clean the thermocouples using a wire brush.

3. After cleaning, reinstall both thermocouples and ensure the y are tight ene d securely.

4. Open all valves that were closed in Step 1 and res tore the heat exchanger to operation.

□ Recirculation Pump

The recirculation pump is located in the recirculation line, just above the Cold Water Input.

1. Turn the power switch on the Control Box to OFF.

2. Ensure that the water has been drained from the unit (see 6.4.1, steps 1-4).

WARNING

BEFORE PERFORMING THE FOLLOWING STEPS, ENSURE THAT THE POWER SWITCH ON THE SIDE OF THE ECS CONTROL BOX IS OFF AND THE HEATER HAS BEEN DRAINED AS SPECIFIED IN

6.4.1, STEPS 1 THROUGH 4.

3. Locate the recirculation pump and disconnect the flanges from the recirculation piping.

4. Without pulling on the e lectrical conduit attached to the recirculation p ump, carefully s lide it out and inspect it.

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□

□ Shell Solids*

□

□ Over-temperature Switch

□

5. If there is evidence of sc ale build-up, disconnect the condu it and el ectric al power lines f rom the pump and service or replace it, as necessary.

6. If there is no evidence of s cale build-up on the recirculation pump, r einstal l it an d r ec onnect t he wiring and flanges.

Table 6-1. Recommended Maintenance Schedule

Maintenance Check Week

Tube Leak

Control Valve Leak

Vacuum Breaker(s)

Over-temperature Switch Alarm

Temperature Controller

Actuator Adjustment

Steam Strainer

Temperature Sensor

Month

(6.3)

√

(6.4)

Quarter

(6.5)

Six Months

(6.6)

Year

(6.7)

Recirculation Pump

* Perform the first test for shell solids upon com pletion of the first three m onths of heat exchanger

operation. Depending upon the results (see 6.4.1, Step 5), repeat this test quarterly, semiannually or annually.

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√

7-1

CHAPTER 7 TROUBLESHOOTING

7.1 INTRODUCTION

This section provides you with troubleshooting proc edures for isolating faults t o the most probable cause whenever malfunctions occur in the heat exchanger (Table 7-1), CXT-E Electronic Control Valve (Table 7-2), or Electronic Control System (ECS; Table 7-3). Table 7-4 provides troubleshooting tips for correcting control s ystem faults, and Table 7-5 provides the d ynamic temperature control settin gs for the three models of the DW-Series water heater product line.

Before performing the tr oubleshoot ing steps and pr ocedures pr ovided in T ables 7-1 throu gh 7-4, com plete the following preliminary checks:

1. ELECTRONIC CONTROL VALVE, CXT-E a. Verif y that all piping conne ctions have been made in accordanc e with Figure 2-4 and that all

electrical connections have been made in accordance with Figure 2-7.

b. Ensure that the Electronic Control Valve (“Valve”) is installed with the flow arro w on the Valve

body pointing in the direction of flow.

c. Ensure that both the upstream and downstream shutoff valves are fully open.

2. ELECTRONIC CONTROL SYSTEM

a. Ensure that all ECS electrical cable connections are secure. b. Ensure that the CXT-E Control Valve actuator is connected to the Control Box cable plug.

NOTE

When system m alfunctions occur, check the troubles hooting sections of the manuals for any other equipment included in this installation, as necessary, in addition to the procedures provided i n this section. Appendix A of this manual contains process fault and diagnostic alarm information for the Eurotherm, Model 2408 Temperature Controller.

7.2 TROUBLESHOOTING PROCEDURES

When a heat exchanger fault occurs, proceed as follows:

1. Refer to the FAULT INDICATION column in the following tables and locate the fault that best describes the existing conditions.

2. Proceed to the PROBABLE CA USE column. If m ore than one item is listed, start with the f irst item shown for the fault condition.

3. Perform the corresponding check s and proc edures list ed in the C ORRECT IVE A CT ION colum n for the first PROBABLE CAUSE.

4. Continue checking each additio nal PROBABLE CAUSE for the existing fault u ntil the fault has been corrected.

5. If component removal and /or replacem ent is required, refer to the appl icable procedures in Chapter 8 Corrective Maintenance.

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Table 7-1. TROUBLESHOOTING – HEAT EXCHANGER

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T1 The heat exchanger

does not maintain the required temperature at rated capacity.

1. The Control Valve does not open.

2. There is a leak in either the inside or outside wall of one or more of the heat exchanger tubes, as indicated by a flow from the leak detection port.

3. Recirculating pump failure.

4. The heat exchanger tubes are scaled up.

5. The heat exchanger is being used at a rate higher than its design capacity.

6. Steam pressure is too low.

7. Condensate is backing up into the heat exchanger because of a restriction in the condensate drain line.

8. The condensate return piping has not been installed so as to enable the condensate to drain freely by gravity, and/or the condensate check valve leaks or has failed.

9. Thermocouple is not installed in the water flow.

10. The Temperature Controller reads wrong.

1. Check the instructions in Table 7-2.

2. Refer to Cha pter 9, secti on 9.2, and proceed as instructed.

3. Proceed as follows: a. Check input power to the re c irc ulation pump.

b. Check the temperature of the copper tube above the pump.

It should be the same as the outlet DHW temperature. If cold, repair or replace the pump, as needed.

4. Contact AERCO or your nearest AERCO representative.

5. Contact AERCO or your nearest AERCO representative.

6. Check the supply pressure gauge ahead of the Control Valve. If the reading is low, adjust the steam supply pressure to the required value. If the steam supply line is restricted, the gauge reading will drop excessively when the heat exchanger calls for full steam, even though the pressure seems to be normal when the load is light. If the steam supply pressure is correct, the steam pressure compound gauge reading should reach design pressure for steam in the heat exchanger tubes as the Hot Water Output temperature starts to drop. If it does not, check the operation of the Control Valve.

7. Contact AERCO or the nearest AERCO representative for the trap size required and make the necessary correction.

8. If necessary, rearrange the condensate return piping to permit condensate to drain freely from the heat exchanger connection. Inspect the condensate check valve and replace it if it is leaking or has failed. Also, ensure that there is no restriction in the condensate drain line.

9. Check to ensure that the thermocouple sheath does not protrude more than ½“ from the compression fitting.

10. Check by replacing the Temperature Controller with one known to be correct.

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Table 7-1. TROUBLESHOOTING – HEAT EXCHANGER, continued

5. The Steam Input does not c lose.

5. Check the instructions in Table 7-2, Item T11.

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T2 Heat exchanger

overheats

T3 Hot water outlet

temperature fluctuates widely

1. Temperature Controller is indicating the wrong value.

2. Water is preheated too hot.

3. Termocouple is not installed in the water flow.

4. Leaking valve in by-pass line, if any, around the Control Valve.

1. The Control Valve does not close.

2. The Control Valve does not open.

3. There is a leak in either the inside or outside wall of one or more of the heat exchanger tubes, as indicated by a flow from the leak detection port.

4. The heat exchanger is being used at a rate higher than its design capacity.

5. Steam pressure is too low.

1. Check by replacing the Temperature Controller with one known to be correct.

2. Reduce the preheating to a temperature at least 10°F below the desired Hot Water Output temperature.

3. Check to ensure that the thermocouple sheath does not protrude more than ½“ from the compression fitting.

4. Maintain the valve to shut tight.

1. Determine if the packing is too tight. See the instructions in Table 7-2.

2. Determine if the packing is too tight. See the instructions in Table 7-2.

3. Refer to Chapter 9, Section 9.2, and proceed as instructed.

4. Contact AERCO or your nearest AERCO Representative for advice in remedying this problem.

5. Check the supply pressure gauge ahead of the Control Valve. If the reading is low, adjust the steam supply pressure to the required value. If there is a restriction in the steam supply line, the gauge reading will drop excessively when the heat exchanger calls for full steam, even though the pressure seems to be normal when the load is light. If the steam supply pressure is correct, the steam pressure compound gauge reading should reach design pressure for steam in the heat exchanger tubes as the Hot Water Output temperature starts to drop. If it does not, check the operation of the Control Valve.

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Table 7-1. TROUBLESHOOTING – HEAT EXCHANGER, continued

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

(Continued) 6. No check valve in the condensate drain line.

7. Condensate is backing up into the heat exchanger because of a restriction in the condensate drain line such as an undersized or faulty trap.

8. The condensate return piping has not been installed so that the condensate drains freely by gravity and/or the condensate check valve leaks or has failed.

9. Recirculation pump is malfunctioning.

T4 Insufficient wat er flow

rate through the heat exchanger

1. Cold Water Input pressure is low.

2. There is a leak in either the inside or outside wall of one or more of the heat exchanger tubes, as indicated by a flow from the leak detection port.

3. Check valves may not be fully open.

6. Lack of this check valve can allow condensate ― and live Steam, if present ― to be drawn back into the heat exchanger from the condensate line. This can result in a high back pressure, water hammer, and, if live steam is present, over-heating. Install a check valve in the

condensate drain line as indicated in Appendix C, Figure C1 through Figure C5.

7. Check AERCO or the nearest AERCO Representative for

the trap size required and make the necessary correction

8. If necessary, rearrange the condensate return piping to

permit condensate to drain freely from the heat exchanger connection. Inspect the check valve and replace it if it is leaking or has failed. Also, check to make sure that there is no restriction in the condensate drain line.

9. Proceed as follows: a. Check input power to the recirculation pump.

b. Check the temperature of the copper tube above the

pump. It should be the same as the outlet DHW temperature. If cold, repair or replace the pump, as required.

1. Check the pressure to the heater and correct, if necessary.

2. Refer to Section 9.2 and proceed as instructed.

3. Verify that the check valves on the CW and DHW sides are

fully open.

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Table 7-1. TROUBLESHOOTING – HEAT EXCHANGER, continued

a temperature

and repair or replace each component as necessary.

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T5 Excess or insufficient

condensate being returned from the heat exchanger

T6 Steam being

discharged from heat exchanger at too high

T7 Pressure/temperature

relief valve pops

1. There is a leak in either the inside or outside wall of one or more of the heat exchanger tubes, as indicated by a flow from the leak detection port.

2. Condensate is backing up into the heat exchanger because of a restriction in the condensate drain line, such as an undersized or faulty trap.

3. The condensate return piping has not been installed so as to enable the condensate to drain freely by gravity, and/or the condensate check valve leaks or has failed.

The heat exchanger tubes are scaled up. Contact AERCO or your nearest AERCO Representative for

1. Static pressure of the Cold Water is too high.

2. Fluid to be heated is prehe ated too hot.

3. Leaking valve in by-pass line, if any, around the Control Valve.

4. Lack of expansion capability in the hot water system.

5. Insufficient shock absorbers.

6. The Control Valve does not close.

7. The Over-temperature Limit Switch is out of adjustment, or some component of the system has failed.

1. Refer to Section 9.2 and proceed as instructed.

2. Check AERCO or the nearest AERCO Representative for the trap size required and make the necessary correction

3. If necessary, rearrange the condensate return piping to permit condensate to drain freely from the heat exchanger connection. Inspect the check valve and replace it if it is leaking or has failed. Also, check to make sure that there is no restriction in the condensate drain line.

advice concerning the required remedy.

1. Make corrections necessary to bring the pressure below the relief valve setting.

2. Reduce the preheating to a temperature at least 10°F below the desired Hot Water Output temperature.

3. Maintain the valve to shut tight.

4. Insert an expansion tank in the Hot Water Output line near the heat exchanger.

5. Insert shock absorbers (water hammer arrestors) in both the cold and hot water systems, as needed to eliminate shock waves.

6. Check the instructions in Table 7-2.

7. Check the Over-temperature Limit Switch setting and adjust to the specified setting (usually 20°F higher than the desired Hot Water Output temperature) (See 4.3.2). Inspect

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Table 7-1. TROUBLESHOOTING – HEAT EXCHANGER, continued

no restriction in the condensate drain line.

Output temperature.

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

(Continued)

T8 Heat exchanger shuts

down below Hot Water

T9 Loud banging in heat

exchanger or in steam piping - not to be confused with the normal clicking noise

8. The condensate return piping has not been installed so as to enable the condensate to drain freely by gravity, and/or the condensate check valve leaks or has failed.

The Over-temperature Limit Switch is out of adjustment or some component of the system has failed.

1. Faulty vacuum breaker.

2. Lack of expansion capability in the hot water system.

3. Insufficient shock absorbers.

4. No check valve in the condensate drain line.

5. Supply steam line is not properly trapped.

6. The condensate return piping has not been installed so as to enable the condensate to drain freely by gravity, and/or the condensate check valve leaks or has failed.

8. If necessary, rearrange the condensate return piping to permit condensate to drain freely from the heat exchanger connection. Inspect the Check Valve and replace it if it is leaking or has failed. Also, check to make sure that there is

Check the over-temperature Limit Switch setting per 4.3.2. Inspect and repair or replace each component as necessary.

1. Check the vacuum breaker for faulty operation. If faulty, replace vacuum breaker.

2. Insert an expansion tank in the Hot Water Output line near the heat exchanger.

3. Insert shock absorbers (water hammer arresters) in both the cold and hot water systems, as needed to eliminate shock waves.

4. Lack of this check valve can enable condensate ― and live steam, if present ― to be drawn back into the heat exchanger from the condensate line. This can result in a high back pressure, water hammer, and if live steam is present, over-heating. Install a check valve in the

condensate drain line as indicated in Appendix C, Figure C1 through Figure C5.

5. Install a trap as indicated in Appendix C, Figure C1 through

Figure C5.

6. If necessary, rearrange the condensate return piping to

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Valve size

Table 7-2 TROUBLESHOOTING – ELECTRONIC CONTROL VALVE CXT-E

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T10 System not operating.

Control Valve is closed and Hot Water Output water temperature is far below setpoint.

CAUTION

Over-tightening the packing nut may trap the Valve stem and slow or stop Valve motion.

T11 System overheats by more

than 10°F above the desired setpoint.

Outlet temperature is below the overtemperature limit setting.

CAUTION

Over-tightening the packing nut may trap the Valve stem and slow or stop Valve motion.

1. Power is not being supplied to the Control Valve.

2. The Actuator has failed.

3. Control signal is not being supplied from the Temperature Controller.

4. The Actuator linkage has failed.

1. Control Valve is not fully closed.

2. Actuator U-bolt loose.

3. The Actuator has failed.

4. Temperature Controller is not set properly or is defective.

5. Actuator is not properly secured to the linkage assembly.

6. Foreign matter in the Control Valve seat

7. Recirculation pump failure.

1. Disconnect Actuator plug and verify that 24 VDC power is present at pin 2 of the Actuator cable. Restore power as necessary. Proceed to Table 7-3, Item T17, and verify that the Over-temperature Switch is not tripped.

2. Replace Actuator.

3. Verify presenc e of 4 – 20 mA control signal at pin 3 of the Actuator cable. If the control signal is not present, troubleshoot ECS per Table 7-3.

4. Check Actuator linkage and verify that it is properly connected and that the pin in the linkage is in the correct position for the installed

1. Check the 4 – 20 mA control signal being supplied to the Actuator. If the signal is greater than 4 mA when the heater outlet temperature is 10°F (or more) above the desired setpoint, proceed to next item ion the list.

2. Check Actuator U-bolt securing it to the linkage assembly. Tighten as needed (per 8.2.4, Step 55) and readjust the CXT-E Control Valve per

4.2.

3. Replace Actuat or .

4. Refer to Chapter 4 Adjustments. Check the current setting of the Temperature Controller. Readjust if necessary. If adjustment does not clear the fault, proceed to Table 7-3, Item T16, and proceed as instructed.

5. Check the Actuator U-bolt that secures the linkage assembly. Tighten if needed and readjust the Control Valve per section 4.2.

6. If the Valve still does not close after checking the above items, disassemble the Valve and clean the seat per 8.2.2, steps 18 –28.

7. Proceed as follows: a. Check input power to the recirculation pump.

b. Check the temperature of the copper tube above the pump. It

should be the same as the outlet DHW temperature. If cold, repair or replace the pump, as required.

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mA control signal are

Table 7-2. TROUBLESHOOTING – ELECTRONIC CONTROL VALVE CXT-E, continued

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T12 System outlet water

temperature is below desired setpoint.

CAUTION

Do not over-tighten the packing nut, as it may trap the Valve stem and slow or stop Valve motion.

1. Temperature Controller is not set properly.

2. Control Valve is not opening properly.

3. Steam pressure is too low

4. Trap in Condensate Output line is malfunctioning.

1. Refer to 4.3.1 and check the cur rent Temperature Co ntroller setting. If the setting is below the desired setpoint, readjust as necessary.

2. Proceed as follows: a. Ensure that the Actuator is correctl y secured to th e Contr ol Valve

linkage assembly. Tighten mounting bolts, as needed.

b. Verify that 24 VDC power and 4 - 20

present at Actuator pins 2 and 3, respectively.

c. To ensure that the Valve is not binding, check the Valve shaft

seal retainer per 8.2.1, steps 1 through 10. Replace items as necessary.

3. Check the high-side steam pressure to the Control Valve to ensure it is correct. a. If steam pressure is lower than the system desi gn specification,

correct as necessary.

b. If the high-side steam pressure drops as the Control Valve

opens, the strainer m ay be clogged, or there may be a part ially closed valve in the upstream line. Correct as required.

4. Check for improper operation of the trap in the Condensate Output line, as follows: a. If the low-side pressure gauge shows pressure, but steam does

not heat properly, CAREFULLY break the Condensate Output line

connection AHEAD of the trap. b. Allow condensate to run out into the floor drain. c. If the heat exchanger outlet temperature rises to the desired

setpoint with the condensate connection open, repair or replace

the trap.

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be Red (-) White (+)]

Table 7-2. TROUBLESHOOTING – ELECTRONIC CONT ROL VALVE CXT-E, continued

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T13 Wide variations in heat

exchanger outlet temperature during wide flow variations.

T14 Rapid fluctuations in heater

outlet temperature which do not follow load changes

T15 System not operating. All

displays are blank.

T16 Love Over-temperature

Switch display is blank.

T17 Hot Water Output

temperature consistently above setpoint by 10°F, or more. However, temperature is below overtemperature limit setting.

1. Mixed water temperature sensor is malfunctioning.

2. Recirculation pump is malfunctioning.

1. Refer to Table 7-3 Item T21, and check the operation of the mixed water temperature sensor.

2. Proceed as follows: a. Check input power to the recirculation pum p.

b. Check the temperature of the copper tube above the pump. It

should be the same as the outlet DHW temperature. If cold, repair or replace the pump, as required.

1. Temperature Controller is malfunctioning.

2. Steam Trap or orifice fault

1. External 120 VAC power is disconnected.

2. Defective ON/OFF power switch on Control Box.

1. Refer to Table 7-3, Items T16 and T19 to troubleshoot the Temperature Controller.

2. Refer to T12, Corrective Action 4 above and proceed as directed.

1. Ensure that the external circuit breaker is ON. Check for 120 VAC power across TB-2 terminal leads 101 (Line) and 102 (Neutral).

2. Set ON/OFF power switch to the ON (Up) position and verify that the switch indicator lights. Also:

a. Verify that 120 VAC is present across TB-2 terminal leads 100

(Line) and 102 (Neutral).

b. If voltage is not present, replace theON/OFF power switch.

Defective DC Power Supply Disconnect the DC output connector on the left internal wall of the

Control Box (Figure 8-12b). Verify that 24 VDC is present across the V+ and V- terminals. If 24 VDC is not present, replace the DC Power Supply.

1. Temperature Controller is not set properly.

2. Faulty Temperature Sensor (thermocouple) is connected to Temperature Controller.

3. Valve Actuator is not properly secured to the linkage assembly.

1. Refer to Chapter 4 Adjustments and check current setting of Temperature Controller. Readjust as necessary.

2. Verify that Hot Water Outlet Temperature Sensor is securely connected to the cable plug. Replace the DHW Outlet Temperature Sensor, if necessary.

3. Verify that the Actuator is securely fastened to the linkage ass embly. Tighten as needed and readjust the CXT-E Control Valve per Chapter 4.

4. Polarity of J-Thermocouple

4. Check polarity of J-Thermocouple connection. Correct, if necessary.

connection is reversed. [Should

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Table 7-3 TROUBLESHOOTING – ELECT RONIC CONTROL SYSTEM

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T18 Over-temperature alarm

occurs repeatedly.

NOTE

Audible alarms will be generated if the Hot Water Output temperature sensor is open. Erroneous temperature readings will be displayed if sensor is shorted.

T19 Over-temperature alarm

condition cannot be cleared. Over-temperature Switch

displays erroneous temperature readings

1. Over-temperature Switch is not set properly.

2. Open or shorted Hot Water Outlet temperature sensor (thermocouple) is connected to the Over-temperature Switch.

3. Over-temperature Switch is defective.

1. Shorted Hot Water Output temperature sensor.

2. Defective Over-temperature Switch

3. A “No-Flow” condition is causing a gradual buildup of heat in the vessel water.

4. External recirculation pump has shut off or has failed.

5. Over-temperature Switch setting is too low.

6. Packing nut is too tight.

7. Over-temperature Solenoid Valve is leaking or open.

1. Refer to Chapter 4 and check the current setting of the Overtemperature Switch. Readjust as necessary.

2. Check thermocouple connections between Hot Water Outlet sensor connector plug and TB-1 terminal leads 111 (+) and 112 (-). If connections are secure, replace the Dual-temperature Sensor.

3. Replace the Over-temperature Switch.

1. Replace Hot Water Output Temperature Sensor.

2. Replace Over-temperature Switch .

3. Open heat exchanger Hot Water Outlet to see if fault clears. If there is no flow through the heat exchanger, see Probable Cause 4.

4. Check pump to ensure that it is turned on and functioning properly. Also, check for blockage in the incoming flow.

5. Refer to Chapter 4 and check the current setting of the Overtemperature Switch. Readjust as necessary.

6. Loosen the packing nut and re-tighten it avoiding the use of excessive force.

7. Inspect the solenoid valve for evidence of leaks. If leaks are detected, replace the solenoid valve.

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Valve is leaking or open.

detected, replace the solenoid valve.

or reversed.

Table 7-3. TROUBLESHOOTING – ELECTRONIC CONTROL SYSTEM, continued

NO. FAULT INDICATION PROBABLE CAUSE CORRECTIVE ACTION

T20 Outlet water temperature is

far below setpoint

T21 Wide fluctuations occur in Hot

Water Output water temperature during large flow changes.

T22 Wide fluctuations occur in Hot

Water Output water temperature under low flow conditions.

1. Incorrect Temperature Controller setting

2. Defective Temperature Controller.

3. Linkage not properly connected.

4. Defective Actuator.

5. Control Valve shaft may be binding

1. Heat exchanger recirculation pump is not operating.

2. Over-temperature Switch setting is too low.

3. Over-temperature Solenoid

1. DHW Outlet Temperature Sensor connected to the Temperature Controller is intermittent.

2. Mixed water temperature sensor is open, shorted or gives inconsistent readings.

3. Recirculation pump has failed

1. Refer to Chapter 4 and check the current setting of the Overtemperature Switch. Readjust as necessary.

2. Disconnect the cable plug from the Valve Actuator and verify that the Temperature Controller is generating a control signal greater than 4 mA. If not, replace the Temperature. Controller.

3. Check the Control Valve linkage to verify that it is properly connected and that the pin in the linkage is in the correct position for the selected Valve size.

4. Replace the Valve Actuator.

5. Refer to Table 7-2, Fault T12, Corrective Action 2c and perform the indicated action.

1. Check the power to the recirculation pump.

2. Refer to Chapter 4 and check the current setting of the Overtemperature Switch. Readjust as necessary.

3. Inspect the solenoid valve for evidence of leaks. If leaks are

1. Replace DHW Outlet Temperature Sensor at the heat exchanger Hot Water Output port.

2. Replace mixed water temperature sensor.

3. Replace recirculation pump.

T23 Hot Water Output

temperature above overtemperature limit, but solenoid (Dump) valve does not open.

Rev B Mar 2013

1. Disconnected or defective solenoid

2. Defective Over-temperature Switch

3. Solenoid valve wiring is loose

1. Verify that 24 VDC is present at the solenoid plug between leads 103(+) and 104 (-).

If voltage is present and the solenoid is connected, replace the

solenoid. If 24 VDC is not present, proceed to Item 2, below.

2. Replace Over-Temperature Switch.

3. Verify that solenoid valve wiring is secure and connected per Figure B-1.

HE-111 − TROUBLESHOOTING

7-12

This page intentionally left blank.

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-1

Size

Figure

Table

1.00” to 2.00”

Figure 8-1

Table 8-1

2.50” to 4.00”

Figure 8-2

Table 8-2

CHAPTER 8 CORRECTIVE MAINTENANCE

8.1 INTRODUCTION

This chapter docum ents AERCO’s recommended cor rective maintenance procedures for the pac kaged assembly of the DW -series heat exchanger, th e CXT-E Control Val ve and the Electronic C ontrol System (ECS). This chapter is organized as follows:

• CXT-E Control Valve (8.2)

• Electronic Control System (8.3)

8.2 CXT-E ELECTRONIC CONTROL VALVE

The corrective maintenance procedures for the CXT-E Control Valve are organized as follows:

• Valve Shaft Seal Retainer Replacement (8.2.1)

• Valve Disassembly (8.2.2)

• Valve Reassembly (8.2.3)

• Actuator Replacement (8.2.4)

• Link age Ass embly Replacement (8.2.5)

Refer to the following drawings and parts list tables to perform the indicated operations on the AERCO Type CXT-E Actuator and Valve Assembly:

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HE-111 − CORRECTIVE MAINTENANCE

8-2

THIS PIN LOCATION TO BE

USED ON ALL 1.0" TO 2.0"

VALVE ASSEMBLY

CONFIGURATIONS

FAR SIDE

ACTUATOR

LINKAGE

INDICATOR PLATE

LINKAGE ADAPTER

SHAFT PIN

Figure 8-1. CXT-E Actuator and Control Valve Assemblies, (Sizes 1.00” To 2.00”)

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HE-111 − CORRECTIVE MAINTENANCE

8-3

1 1 VALVE BODY

20762

20759

20758

20761

2 1 SEAT CAGE

16844

16845

16837

16843

3 1 BOTTOM PISTON

121540

121525

121502

121529

4 NOT USED

5 1 VALVE PLUG SHAFT

16849

16839

16838

16848

6 1 TOP PISTON

121539

12154

121501

121530

7 1 DISC SEAT

121541

121527

121510

121531

8 1 RETAINING DISC

121542

121513

121504

121532

9 NOT USED

PILOT SPRING

121528

RETAINING RING

121545

VALVE STEM

122655

122654

122651

122650

VALVE TOP GASKET

122136

BOLT, HEX, 3/8-16

122405

LOWER SHAFT

121979

121980

121982

HEX NUT, 1/4-20

6-226

PACKING NUT

122664

BOLT, HEX 3/8-16 x 5/8 LG

54014

PACKING ASSY

121567

VALVE TOP

16943

NOT USED

LOCKWASHER

122666

SEAT CAGE GASKET

123080

123081

123082

123083

LINKAGE

24038-1

ACTUATOR

69009

SCALE

59028-1

59028-1.25

59028-1.5

59028-2

Table 8-1. PARTS LIST FOR VALVE ASSEMBLIES, TYPE CXT-E ( SIZES 1.00” TO 2.00”)

VALVE SIZE AND PART NUMBERS

ITEM QTY PART NAME 1.00 INCH 1.25 INCH 1.50 INCH 2.00 INCH

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HE-111 − CORRECTIVE MAINTENANCE

8-4

Table 8-1. PARTS LIST FOR VALVE ASSEMBLIES, TYPE CXT-E (SIZES 1.00” TO 2.00”),

VALVE SIZE AND PART NUMBERS

ITEM

QTY

PART NAME

1.00 INCH

1.25 INCH

1.50 INCH

2.00 INCH

9929

HEX NUT, #8-32

123322

BOTTOM PISTON RETAINING NUT

122982

TOP PISTON RETAINING NUT

121543

LOWER PILOT SEAT ASSY

121505

SEAT RETAINER

N/A

121559

121506

VALVE STEM RETAINING NUT

121503

continued

9999

1 GASKET 81046 81046 81046 81046

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HE-111 − CORRECTIVE MAINTENANCE

8-5

ACTUATOR

LINKAGE

SHAFT PIN

LINKAGE ADAPTER

INDICATOR PLATE

Figure 8-2. CXT-E Actuator and Control Valve Assemblies (Sizes 2.50” To 4.00”)

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HE-111 − CORRECTIVE MAINTENANCE

8-6

1 1 VALVE BODY

20765-1

20766-1

20775

2 1 SEAT CAGE

16961

161004

161046

3 1 BOTTOM PISTON

16962

161007

161048

4 1 PISTON RETAINING RING

122173

122234

5 1 VALVE PLUG SHAFT

16972

161006

161047

6 1 TOP PISTON

16970

161005

161050

7 1 VALVE SEAT

121935

122032

122178

8 1 VALVE SEAT RETAINING DISC

121934

122031

122177

CAP SCREW

PILOT SPRING

122081

122232

121823

PILOT SPRING RETAINER

122082

122173

VALVE STEM

122648

122658

122659

VALVE TOP GASKET

122083

122204

122203

CAP SCREW 5/8-11 x 1-1/2” LG.

N/A

6-310

3/8-16 NUT (4” VALVE ONLY)

N/A

6-264

LOWER SHAFT

122223

122230

122224

HEX NUT, 1/4-20

6-226

N/A

PACKING NUT

122664

122665

3/8-16 x 5/8” LG. CAP SREWS

54014

PACKING ASSY

121567

121568

VALVE TOP

18781

18823

18824

SEAT BACK-UP RING

122326

122327

122328

LOCKWASHER

122666

122667

SEAT CAGE GASKET

123084

123085

123086

1/4” HEX HD. NPT PLUG

9-22

Table 8-2. PARTS LIST FOR VALVE ASSEMBLIES, TYPE CXT-E ( SIZES 2.50” TO 4.00”)

VALVE SIZE AND PART NUMBERS

ITEM QTY PART NAME 2.50 INCH 3.00 INCH 4.00 INCH

9 4 10-32 x 3/4” LG. SOCKET HD.

122174 122174 122238

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HE-111 − CORRECTIVE MAINTENANCE

8-7

Table

LINKAGE

24038-1

24038-2

ACTUATOR

69009

2.50

GASKET

81046

HEX NUT, 8-32

123332

123322

WASHER

8-2. PARTS LIST FOR VALVE ASSEMBLIES, TYPE CXT-E ( SIZES 2.50” TO 4.00”),

continued

VALVE SIZE AND PART NUMBERS

ITEM QTY PART NAME 2.50 INCH 3.00 INCH 4.00 INCH

28 1 SCALE 59028-

31 1 PILOT SPRING BACKUP

N/A N/A 122246

59028-3 59028-4

8.2.1 Valve Shaft Seal Retainer Replacement

WARNING

BEFORE PROCEEDING WITH THIS OPERATION, ENSURE THAT THE CONTROL VALVE HAS BEEN ISOLATED FROM THE STEAM SUPPLY. LIVE STEAM CAN CAUSE SERIOUS BURNS TO PERSONNEL.

WARNING

ENSURE THAT ELECTRICAL POWER TO THE ELECTRONIC CONTROL SYSTEM AND ACTUATOR HAS BEEN DISCONNECTED. SERIO US INJURY TO PERSONNEL CAN RESULT IF THIS WARNING IS NOT OBSERVED.

To replace the valve shaft seal retainer proceed as follows:

1. Referring to Figure 8-1 or Figure 8-2, loosen the hex nuts (17) under the i nd icator plat e ap prox imately one-half turn clockwise.

2. Disconnect the linkage adapter from the valve shaft (16) by turning th e shaft clockwise (as viewed from above). If the valve shaft cannot be turned by hand, use an open-end wrench to turn the “double-nuts” on the shaft until it disengages the linkage adapter threads.

3. Remove the indicator plate from the Valve shaft (16).

4. Remove the two cap screws (19) securing the linkage assembly (26) to the Valve top (21).

5. With the Actuator assembly (27) still attac hed, remove the complete linkage assembl y (26) f rom the valve top. Also, remove the gasket (29).

6. If the packing nut (18) is leaking or binding the Valve shaft, replace it.

7. Measure and record the current position of the hex nuts (17) from the end of the Valve shaf t (16). This will simplify adjustment of the Actuator linkage during reassembly.

8. Completely remove the hex nuts (17) from the Valve shaft (16).

9. Remove the packing nut (18) and the packing assembly (20) from the Valve body.

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-8

CAUTION

In the following steps, avoid over-tightening the packing nut (18), which can trap the Valve stem and slow or stop Valve motion.

10. Replace BOTH the packing nut (18) and the packing assembly (20) with a NEW packing nut and packing assembly.

11. Replace the hex nuts (17) onto the Valve shaft (25) and position them in the sam e location noted in step 7.

12. Attach the Actuator (27), linkage (26) an d gasket (29) t o the Valve top using th e two cap screws (19) provided.

13. Install the indicator plate on the Valve lower shaft (16) and secur e it in plac e with the linkage adapter.

14. Reconnect the linkage adapter to the linkage shaft b y replacing the shaft pin.

15. CriticaStepl: Autostroke the Valve and check for leaks.

8.2.2 Valve Disassembly

Refer to Figure 8-1 or Figure 8-2 and proceed as follows:

16. Close the upstream and downstream shutoff valves before and after the CXT-E Control Valve.

17. If the CXT-E Control Valve is easily accessib le for disassembly and reassem bly, leave it installed in the Steam Input line. If it is not easily accessible, re move the Valve from the line and clam p it in a bench vise for easy accessibility.

18. Completely remove the Actuator (27) and linkage assem bl y (26) from the Valve body, as described in steps 1 through 5, above .

19. The following steps cover c omplete Valve disassem bly, in the event it shou ld ever be required. IT IS STRONGLY RECOMMENDED, however, that the Valve be disassembled only to the extent necessary to restore it to proper operation. W hen disassembling the Valve, USE EXTREME CARE not to mar or scratch any surfaces.

The following steps assum e that the Actuator and linkage assemblies ha ve been removed from the Valve body.

20. Remove the following Valve parts in the order specified:

CAUTION

CAREFULLY remove the p acking nut (18) and cap screws (14) (listed below) t o relieve

any trapped pressure. a. Hex nuts (17) b. Packing nut (18) c. Packing assembly (20) d. Cap screws (14) e. Valve top (21) f. Valve top gasket (13)

21. Grasp the lower shaft (16) and carefully remove the ENTIRE shaft/seat/piston assembly.

22. For 1-inch through 2-inch Contro l Valves (Figure 8-1), disassem ble the shaft/seat/pisto n assembly in the following order:

a. Lock washer (23) b. Retaining ring (11) c. Pilot spring (10) d. Valve stem retaining nut (35)

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-9

e. Lower shaft (16) and Valve stem (12) f. Retaining disc (8) g. Disc seat (7) h. Seat retainer (34) i. Valve plug shaft (5)

23. For 2.5-inch, 3-inch and 4-inch Control Valves, (Figure 8-2), disassemble the shaft/seat/piston assembly in the following order:

a. Lock washer (23) b. Pilot spring retainer (11) c. Pilot spring backup washer (31), 4-inch Valve only d. Pilot spring (10) e. Cap screws (9) f. Valve seat retaining disc (8) g. Lower shaft (16) and Valve stern (12) h. Valve seat (7) i. Top piston (6) and bottom piston (3) assembly

24. DO NOT DISASSEMBLE the seat cage (2) u nl ess you need to replace it. If seat cage replac ement is required, see Step 30.

NOTE

In any cleaning operation called for in these instructions, ALWAYS clean the denoted parts thoroughly, rem oving all dirt and scale. Always u se a clean cloth and, if necessar y, a solvent. NEVER use emery cloth or sandpaper unless instructed otherwise herein.

25. CLEAN ALL PARTS THOROUGHLY. ALL DIRT AND/OR SCALE MUST BE REMOVED from the outer surfaces of the Valve Plug shaft (5) (Figure 8-1), or the Top Piston (6) and Bottom Piston ( 3) (Figure 8-2) and from the surface of the Valve stem (12).

26. Inspect the Valve stem (12). If the Valve stem (12) is damaged or does not seat pr oper l y on the V al ve seat (7), or if it does not move freel y in the Valve seat retaining disc (8), replace the Valve stem ( 12), pilot spring retainer (11) and pilot spring (10).

27. Inspect the outer surfaces of the Valve plug (5) or the top piston (6) and bottom piston (3). If they are scored or damaged such that they will not m ove freely up and d own in the Seat Cage (2) , the Valve plug or pistons must be replaced. Reassembly instructions are provided below beginning with step 33.

28. Inspect the Valve seat (7). Replace the Va lve seat if it is worn and does not seat properly with the seat cage (2) (or with the Valve stem (12), in the case of 2.5 to 4 inch Valves).

29. THOROUGHLY clean and inspect the sea ting and inner surfaces of the seat cage (2). Replac e the cage (2) if the seating sur face around th e top of the cage is worn or so d amaged that the Valve seat (7) will not seat proper ly, or if the inner surf aces of the cage are s cored or are so dam aged that the Valve plug (5) or pistons (3) and (6) do not move up and down freely.

30. If it is necessary to remove the cage (2) from the Valve body (1), first fabricate a tool similar to the one illustrated in of the Valve body. You may also obtain a cage removal tool from AERCO by contacting AERCO directly or through your nearest sales representative.

Rev B Mar 2013

Figure 8-3. Insert the tool into the slots on top of the cage (2) and turn the cag e out

HE-111 − CORRECTIVE MAINTENANCE

8-10

BAR 1/4" SQUARE

TOOL STEEL

WELD ON INSIDE

ONLY

VALVE SIZE

1-INCH 1-1/4 INCH 1-1/2-INCH

2-INCH

2-1/2-INCH

3-INCH

ALL DIMENSIONS SHOWN ARE IN INCHES

1.25" 1.50"

PIPE OR TUBING - A

1" SCH. 40 PIPE 1-1/4" SCH. 40 PIPE 1-1/2" SCH. 40 PIPE 2-1/2" OD x .120" WALL

SEAMLESS STEEL TUBING

2-1/2" OD x .120" WALL SEAMLESS STEEL TUBING

3" OD x .120" WALL SEAMLESS STEEL TUBING

1.11 1-5/8

1.42

1.67

2.40

2.895

3.476

2-3/8

2-5/8

3-3/8

3-15/16

HANDLE – 1 /2" DIA COLD ROLLED STEEL

WELD

C D

7-1/2

8-1/4

9-1/2

TOOLS FOR 1-INCH TO 3-INCH VALVES

1/2" STEEL

PLATE

1/4" SQUARE BAR

TOOL STEEL

4-1/2

TOOL FOR 4-INCH VALVE ONLY

1/4

WELD

1/2

2" SCH. 40 PIPE

Figure 8-3. Cage Removal Tool

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-11

8.2.3 Valve Reassembly

Refer to Figure 8-1 or Figure 8-2 when performing the following procedures.

31. If the seat cage has been rem oved, plac e a NEW seat cage gasket (24) on the se ating s urf ace of the Valve body. W hen this has been accom plished, use the tool des cribed i n Step 29 to replace the seat cage (2) in the Valve body (1). Ensure that the seat cage fits tightly.

32. If they have been disassembled or are being replaced, reassemble the top piston (6) and bottom piston (3) onto the Valve plug shaft (5) using the top piston retaining nut (46) (for 1-inch through 2-inch Valves), and the bottom piston retaining nut (50) or bottom piston retaining ring (4).

33. For 1-inch through 2-inch Control Valves, (Figure 8-1), reassemble the valve plug/seat/shaft assembly in the following order:

a. Valve plug (5) b. Seat retainer (34) c. Valve seat (7) d. Retaining disc (8) e. Valve stem (12) and lo wer s haf t (16) f. Valve stem retaining nut (35) g. Pilot spring (10) h. Pilot spring retaining clip (3) i. Lock washer (23)

34. For 2.5-inch, 3-inch and 4-inch Control Valves (Figure 8-2), reassemble the piston/seat/shaft assembly in the following order:

a. Top piston (6) and bottom piston (3) assembly b. Valve seat (7) c. Valve stem (12) and lower shaft (16) d. Valve seat retaining disc (8) e. Cap screws (9) f. Pilot spring (10) g. Pilot spring backup washer (31), 4-inch Valve only h. Pilot spring retainer (11) i. Lock washer (23)

35. Holding the lower shaft (16), carefully replace t he entire shaft/seat/piston assem bl y into the V alve body (1) and seat cage (2).

36. Thoroughly clean the gasket surf aces of the Valve body (1) and Valve t op (21) o f all dirt a nd scale. If necessary, use a wire brush, emery cloth or both.

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-12

37. Referring to Figure 8-1 or Figure 8-2, reassemble the following parts in the order indicated: a. NEW Valve top gasket (13) b. Valve top (21) c. Cap screws or hex-head bolts (14):

• For valve sizes 2-1/2” to 4” use 1/2-13 cap screws

• For valve sizes 1” to 2” use 3/8-16 hex-head bolts

Tighten the cap screws using an alternating pattern to provide a uniform seal and prevent Valve

leakage. d. NEW packing assembly (20) e. Packing nut (18) f. Hex nuts (17) g. Indicator plate (See Figure 8-1 or Figure 8-2)

38. Replace the Actuator (27), linkage (2 6) and gasket (29) onto the Valve top (21) and secur e with cap screws (19).

39. Position the hex nuts (17) in the original location noted during the removal process (Step 7).

40. Install the indicator plate on the Valve shaft (16) with the curved end facing upward (Figure 8-6).

41. Attach the Valve shaft (16) to the linkage adapter b y rotating the shaft counterclock wise (as viewed from above). If the Valve shaft cannot be turned by hand, use an open-end wrench to turn the “double-nuts” on the shaft until it engages the linkage adapter threads. Insert the shaft into the linkage adapter until the hex nuts (17) are snug against the indicator pl ate.

42. Press down on the Valve shaft (16) to compress the pilot spring (10) in the Valve body.

43. With the pilot spr ing compress ed, verify that the indicator plat e is aligned with th e “0” (zero) m arking on the scale (28). If necessary, rotate the Valve shaft until the plate is aligned with the “0” scale marking.

44. If the Valve had been removed f rom the steam line, replace it and reconnect the electrical connector plug to the Actuator.

45. Before placing the Valve back into service, adjust the CXT-E Actuator according to Section 4.2.

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-13

24038-2 (4” Valve)

59028-4 (4” VALVE)

3 2 HEX NUT, 8-32

123322

4 2 CAP SCREW, 3/8-16 x 5/8 LO NG

54014

5 1 LINKAGE GASKET

81046

SHAFT PIN LOCATION

LINKAGE

ASSEMBLY

LINKAGE ADAPTER

INDICATOR PLATE

(CURVED END)

HEX NUTS (2) VALVE SHAFT PACKING NUT

CAP SCREW

LINKAGE

GASKET

ITEM QTY PART DESCRIPTION PART NUMBER

1 1 LINKAGE ASSEMBLY 24038-1 (1” TO 3” VALVES)

2 1 SCALE 59028-1 (1” VALVE)

VALVE BODY

INDICATOR PLATE

VALVE TOP

59028-1.25 (1.25” VALVE)

SCALE

8-32 HEX NUT (FAR SIDE)

59028-1.5 (1.5” VALVE) 59028-2 (2” VALVE) 59028-2.5 (2.5” VALVE) 59028-3 ( 3” VALVE)

Figure 8-4. linkage Assembly Installation Details

8.2.4 Actuator Replacement

The Actuator includes no repairable parts. Therefore, if the troubleshooting procedures point to the Actuator as the cause of the fault, replace it as described in the following steps:

46. Disconnect and lock-out/tag-out the AC power supplied to the Control Box . Use a voltm eter to ens ure that all voltages are zero before continuing.

47. Disconnect the Control Box cable connected to the Actuator.

48. Use an 8-mm wrench to loosen the hex nuts securing the Actuator to the linkage shaft.

49. Completely remove the defective Actuator from the shaft.

50. To install a replacem ent Actuator, d epress and hold the clutch button (see Figure 8-5) and rotate the pointer to approximately 80° on the dial. Release the clutch.

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-14

neptronic

1 2 3

COVER SET SCREW

CLUTCH PUSHBUTTON

DIAL &

POINTER

CENTER

SLOT

COVER

CABLE

CONNECTOR

LINKAGE

SHAFT

51. Slide the Actuator onto the linkage shaft.

52. Ensure that the pin on the linkage assembly is inserted in the center slot on the bottom of the Actuator (Figure 8-5).

53. Verify that the indicator plate on the linkage assembly is aligned with “0” ( zero) on the linkage scale. Also, ensure that the Actuator dial is approximately at the 80° position.

54. Ensure that the pin on the linkage is inserted in the center slot on the Actuator.

55. Use an 8-mm wrench to ti ghten th e hex nu ts on the U-bolt to secure the Actuator to the shaf t. T orque the hex nuts to 60 inch-pounds.

56. Reconnect the Control Box cable to the Actuator.

57. When you have completed the Actuator replacement, perform the Control Valve adjustment procedure in Section 4.2.

Figure 8-5. Actuator

8.2.5 Linkage Assembly Replacement

As illustrated in Figure 8-6, the linkage assembly part number w ill vary according to the va lve size. The CXT-E valve sizes ranging from 1.00 to 3.00 inches use linkage assembly Part No. 24038-1. The

4.00-inch CXT-E Valves use linkage assembly, Part No. 24038-2. The primary difference between the

24038-1 and 24038-2 linkage ass emblies is the adapter shown in Figure 8-6. In addition, the linkage pin location for the 24038-1 assembly is different for 1.00 to 2.00-inch valves and 2.50 to 3.00-inch valves .

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-15

ADAPTER

PART NO. 24038-1

(FOR 1 TO 3 IN. VALVES)

USE THIS PIN

LOCATION FOR

4 IN. VALVES

USE THIS PIN

LOCATION FOR

1 - 2 IN. VALVES

ADAPTER

PART NO. 24038-2

(FOR 4 IN. VALVE ONLY)

13 - 3/8 IN.

4–1/2 IN. x

1-15/16 IN. WIDE

USE THIS PIN

LOCATION FOR

2 -1/2 & 3 IN.

VALVES

INDICATOR

PLATE

INDICATOR

PLATE

IMPORTANT

FOR PROPER OPERATION OF THE CONTROL VALVE, IT IS IMPERATIVE THAT YOU USE THE CORRECT ADAPTER AND PIN LOCATION FOR THE VALVE SIZE BEING REPAIRED.

The linkage assembly is attached to the Control Valve to p with two cap screws. Be sure to replac e the linkage gasket (Part No. 81046) each time you install a new linkage assembly.

Figure 8-6. Linkage Assemblies

Use the following procedure when you need to remove and replace the linkage assembly:

58. Remove the Actuator per steps 46 through 49.

59. Refer to Figure 8-1 (for 1 to 2-inch Valves) or Figure 8-2 (for 2 ½ to 4-inch Valves) to locat e the items identified in parentheses in the following steps.

60. Rotate (loosen) the hex nuts (17) under the indicator plate approximately one half-turn clockwise.

61. Disconnect the linkage adapter f rom the Valve shaft (16) by turning the shaft clockwise (as viewed from above). If the Valve shaft cannot be turned by hand, use an open-end wrench to turn the “double-nuts” on the shaft until it disengages the linkage adapter threads.

62. Remove the indicator plate from the Valve shaft (16).

63. Remove the two cap screws (19) securing the linkage assembly (26) to the Valve top (21).

64. Remove the linkage assembly (26) from the Val ve top. Also, remove th e gasket (29) (which will not be retained).

Rev B Mar 2013

HE-111 − CORRECTIVE MAINTENANCE

8-16

HOT WATER OUTPUT

CAUTION

Ensure that the replacem ent linkage assembly, adapter and scale are identical t o those removed in previous steps. Also, ensure that the linkage pin (Figure 8-6) is set to the proper position for the Control Valve size. Failure to observe this precaution may result in improper Control Valve operation.

65. Using a new gasket (29), posit ion the replacement linkage assembly on the Valve top (21). Secure the linkage assembly to the Valve top using the previously removed cap screws (29).

66. Install the indicator plate on the Valve shaft (16) with the curved end facing upward (Figure 8-4)

67. Attach the Valve shaft (16) to the linkage adapter by rotating the shaft countercloc kwise (as viewed from above). If the Valve shaft cannot be turned by hand, use an open-end wrench to turn the “double-nuts” on the shaft until it engages the linkage adapter threads. Insert the shaft into the linkage adapter until the hex nuts (17) are snug against the indicator plate.

68. Press down on the Valve shaft (16) to compress the pilot spring (10) in the Valve body.

69. With the pilot spring com pressed, verify that the indicator plate is aligned with the “0” (zero) on the scale (28). If necessary, rotate the Valve shaft until the plate is aligned with “0”.

70. Replace the Actuator using steps 50 through 57, above.

8.2.6 Recirculation Pump Replacement

The recirculation pump is required to assure proper heat exchanger operation and has an expected service life of five years. The pum p is installed in the recirc ulation piping (see Figure 8-7) to continuousl y circulate domestic water through the heat exchanger, even when there is no DHW demand.

RELIEF VALVE

TOP HEAD

RECIRCULATION PIPING

RECIRULCATION PUMP

COLD WATER INPUT

CONTROL BOX

AERCO

SHELL ENCLOSING THE TUBE BUNDLE

PLUGGED DRAIN

BOTTOM HEAD

POWER SWITCH

CXT-E ACTUATOR

CXT-E CONTROL VALVE

CONDENSATE OUTPUT

STEAM INPUT

Figure 8-7. Recirculation Pump Mounted in Recirculation Piping

Use the following procedure to replace the recirculation pump:

1. Turn OFF both t he external power circuit breaker to the DW-series heat exchanger and the power switch on the side of the Control Box.

2. Close all stop valves in the Steam Input and Condensate Output lines.

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3. IN THE FOLLOWING ORDER, close the stop valves in the:

a. Hot Water Output line b. Recirculation line c. Cold Water Input line When the heat exchange has been shut down accor ding to steps 1 and 2, drain the heat exchanger as

follows:

4. CAREFULLY open the rel ief valve in the heat excha nger u pper hea d assem bly to rel ieve press ure in the heat exchanger s hell. If fluid continues to flow from the relief valve, one of the cold water s top valves is either leaking or is not shut tightly. Stop the flow from the relief valve and proceed.

5. Holding the relief valve open (to pr event creating a vacuum in the shell), open the plugged drain at the bottom of the Heater Shell and drain the heat exchanger completely.

6. Disconnect the power leads from the recirculation pump.

7. Remove the bolts on the re c irc ulation pump flanges and slide the pump out from between the flanges.

8. When installing the replacement recirculation pump, ensure that the seals are in place and not pinched.

9. Reinstall the flange bolts and reconnect the power leads to the pump.

10. Refill the heat exchanger and put it back into operation in accordance with section 5.3, steps 1 through 14.

8.3 ELECTRONIC CONTROL SYSTEM

The corrective maintenance procedures for the ECS consist of replacing the Control Box components and subassemblies that were identified as being faulty following the procedures listed in Chapter 7 Troubleshooting. The ECS replaceable items include the:

• Control Box Assembly (8.3.1)

• Temperature Controller (8.3.2)

• Over-temperature Switch (8.3.3)

• DC Power Supply (8.3.4)

• DC Voltage Regulator (8.3.5)

WARNING

BE SURE TO TURN OFF THE CONT ROL BOX POW ER SWITCH (s ee Figure 8-7) AND DISCONNECT AC POWER BEFORE PERFORMING ANY CORRECTIVE MAINTENANCE PROCEDURES LISTED IN THIS SECT ION. FAILURE TO OBSERVE THIS WARNING CAN RESULT IN SERIOUS PERSONAL INJURY.

8.3.1 Replacing the Control Box Assembly

If necessary, replace the complete Control Box assembly as follows:

1. Referring to Figure 8-8, loosen the captive screws on the Control Box door and the recessed panel.

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8-18

REAR

TB-2

LINE

NEUTRAL

GROUND

100

101

102

GND

FRONT

VOLTAGE

REGULATOR

TERMINAL

BLOCK TB-2

EXTERNAL POWER WIRING

(120 VAC)

PT.NO.

SET

AUTO

RUN

MAN HOLD

OP 1

OP 2

SP2

REM

2408

OVER TEMP SWITCH

TEMP CONTROLLER

PT.NO.

PANEL CAPTIVE

SCREW

OVER-

TEMPERATURE

SWITCH

RECESSED

PANEL

PANEL DOOR

2408

RUN

AUTO

HOLD

MAN

TEMP CONTROLLER

PT.NO.

OVER TEMP SWITCH

CAPTIVE SCREW

Figure 8-8. Control Box and Recessed Panel

2. Swing down the recessed panel and locate Terminal Block TB-2 (Figure 8-9).

Figure 8-9. Control Box Interior Bottom View Showing Power Connections

3. Disconnect the Line, Neutral and Ground leads connected to Terminal Block TB-2.

4. Referring to figures in previous chapter s (identified below), disconnect the Control Box c ables from the following devices:

a. Figure 1-3: Disconnect t he Actuator cable (ter minated in a 3-pin Molex connect or) from the

b. Figure 2-1. Disconnect the outlet tem perature dual sensor cables (terminated in 4-pin Molex

Control Valve Actuator.

connectors) from the DHW outlet dual temperature sensor installed in the upper head

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8-19

assembly of the heat exchanger.

c. Figure 2-1. Disconnect the solenoid cable (terminated in a 3-pin DIN connector) from the

Over-temperature Solenoid Valve on the upper head assembly of the heat exchanger.

d. Disconnect the mixed temperature cable (terminated in a 2-pin Molex connector) from the

mixed temperature sensor mounted at the Cold Water Input to the heat exchanger.

5. After the Control Box cable s have been d isconnected, remove the t wo hex nuts s ecuring the Control Box top and bottom mounting attachments to the heat exchanger. Completely remove the Control Box from the heat exchanger.

6. To replace the Control Box, reverse Steps 1 through 5.

8.3.2 Replacing the Temperature Controller

The Temperature Contro ller is located on the recesse d panel behind the Control Box door , as shown in Figure 8-8. Remove and replace the Temperature Controller as follows:

1. Open the Control Box door to access the Temperature Controller.

2. The Temperature Controller is installed in a sleeve as shown in Figure 8-10. To unplug and remove the Temperature Controll er from its sleeve, pry the latching ears outward and pu ll the Temperature Controller out of the panel.

3. To install a replacement Temperatur e Controller, slide it into the front panel sl eeve until the latching ears click into place. When the new Temperature Controller is in place, adjust the setpoint to the required temperature using the adjustment procedures in 4.3.1.

Figure 8-10. Temperature Controller Installation

4. Close and secure Control Box front door.

8.3.3 Replacing the Over-temperature Switch

The Over-temperature Switch performs a switching function and generates an alarm when the preset temperature limit is exceeded. Remove and replace the Over-temperature Switch as follo ws:

1. Open the Control Box door and locate the Over-temperature Switch (Figure 8-11a).

2. Loosen the captive scre w on up per p art of r ecess ed p anel b ehind the do or and o pen the sw ing-down panel to access the term inal wiring connections and retainin g clips of the Over-temperature Switc h assembly.

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To uninstall, push tab to

3. Loosen the terminal wiring connec tion screws on the rear of the Over-temperatur e Switch assembly and disconnect the wires.

4. To remove the Over-temperature Switch assembly, push in tab of each of two side retaining clips (Figure 8-11b), slide toward rear and remove.

Figure 8-11a. Over-Temperature Switch & Temperature Indicator

release clip retainer. Slide clip back and off. Remove

assembly through front

panel.

Figure 8-11b. Over-Temperature Switch & Temperature Indicator Installation

5. If the replaced unit is an Over-tem perature Switc h, set the desir ed over-temperature alarm lim it using the adjustment procedures in Chapter 4, Section 4.3.2.

6. Following adjustment (if necessary), raise and secure the swing-down panel. Cl ose and secure the Control Box door.

8.3.4 Replacing the DC Power Supply

To replace the DC Power Supply, please refer to Figure 8-11a through 8-12d and proceed as follo ws:

1. Open the Control Box door and loosen the captive screw on the recessed panel inside the door.

2. Open the swing-down panel an d locate the DC Power Sup ply on the left interior wall of the Co ntrol Box (View A - A).

3. Disconnect the AC input po wer connector near the bottom of the Power Supply and the DC output connector near the top.

4. Remove the four hex standof fs and lock washers sec uring the DC Power Supply to the studs on the interior side wall of the Control Box. Completely remove the DC Power Supply from the Control Box.

5. Replace the DC Power Supply by reversing the previous steps.

8.3.5 Replacing the DC Voltage Regulator

To replace the DC Voltage Regulator, please refer to Figure 8-11a through 8-12d and proceed as follows:

1. Open the Control Box door and loosen the captive screw on the recessed panel behind the door.

2. Open the swing-down panel and locate the DC Voltage Regulator on the bottom of the chassis interior (View D – D).

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HE-111 − CORRECTIVE MAINTENANCE

8-21

69012-1

2408

AUTO

MAN

HOLD

RUN

OVER TEMP SWITCH

PT.NO.

TEMP CONTROLLER

NOTE

SEE SHEET 5 FOR PARTS LIST

SIDE VIEW - TYPICAL

POWER ON

OFF

POWER IN

3. Disconnect the wiring connector plug shown in View D – D.

4. Remove the four hex nuts and lock washers securing the R egulator to t he studs on the bottom of the chassis. Completely remove the DC Voltage Regulator from the Control Box.

5. Replace the DC Voltage Regulator by rever s ing the pr ev ious ste ps .

Figure 8-11a. ECS Control Box Assembly Component Locations

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HE-111 − CORRECTIVE MAINTENANCE

8-22

POWER SUPPLY

INTERIOR LEFT WALL

VIEW A -A

DC OUTPUT CONNECTOR

AC INPUT CONNECTOR

AC POWER

CABLE

CUTOUT

2 1 1A

AC POWER ON/OFF SWITCH

INTERIOR RIGHT WALL

VIEW B -B

Figure 8-12b. ECS Control Box Assembly Component Locations

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HE-111 − CORRECTIVE MAINTENANCE

8-23

NOTE: SEE APPENDIX C FOR WIRING CONNECTIONS

VIEW C - C

INTERIOR BACK WALL

TERMINAL

BLOCK TB-1

AC POWER

TERMINAL

BLOCK TB-2

REAR

INTERIOR BOTTOM SURFACE

VIEW D - D

VOLTAGE

REGULATOR

INPUT/OUTPUT

CONNECTOR

TB-2

Figure 8-12c. ECS Control Box Assembly Component Locations

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HE-111 − CORRECTIVE MAINTENANCE

8-24

OVERTEMP SWITCH

7 8 9 10 11

1 2

TEMPERATURE CONTROLLER

V+ V-

1A 1B

VIEW E – E

PANEL REAR

1 1 69011-1

CONTROL BOX (STEAM/WATER)

USED

3 1 64028-12

TEMPERATURE CONTROLLER

4 1 64007

OVER-TEMP SWITCH/TEMP INDICATOR

5 1 60003

ON/OFF SWITCH

6 1 63009-4

CONTROL BOX, COMPLETE EXTERNAL HARNESS (S/W)

USED

8 1 65006

POWER SUPPLY

9 1 65007

TERMINAL BLOCK, 4-POSITION (TB-2)

64011

VOLTAGE REGULATOR

65008

TERMINAL BLOCK, 20-POSITION (TB-1)

Figure 8-12d. ECS Control Box Assembly Component Locations

Table 8-3. ECS Control Box Assembly Parts List

ITEM QTY PART NO. DESCRIPTION

NOT

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8-25

Table 8-3. ECS Control Box Assembly Parts List, continued

REQ’D

TABLE 8-5

62004

PLUG

53011

LOCK WASHER, #4

65010

STANDOFF

53010

LOCK WASHER, #8

56012

HEX NUT, #8-32

56011

HEX NUT, #6-32

53012

LOCK WASHER, #6

56010

HEX NUT, #4-40

62002

STRAIN RELIEF

62003

PLUG

THE FOLLOWING INTEMS ARE NOT ILLUSTRATED IN FIGURE 8-12

63007

AC WIRE HARNESS

63008-1

CONTROL BOX CONN. WIRE HARNESS

All Heat Exchangers

1 63009-51

SOLENOID VALVE WIRING HARNESS

2 63009-52

HOT WATER OUT –TO-TEMPERATURE CONTROLLER WIRING HARNESS

3 63009-53

HOT WATER OUT –TO-OVER-TEMPERATURE SWITCH WIRING HARNESS

4 63009-59

ACTUATOR WIRING HARNESS

All Steam-to-Water Double-Wall Heat Exchangers with Serial Number H-09-430 and Above

5 63009-58

MIXED INLET TEMPERATURE WIRING HARNESS

6 63009-61

RECIRCULATION PUMP WIRING HARNESS

64009-1

RS232 COMMUNICATIONS BOARD

64009-2

RS485 COMMUNICATIONS BOARD

ITEM QTY PART NO. DESCRIPTION

SEE

COMMUNICATION BOARD

Table 8-4. Individual Component Wiring Harnesses

ITEM QTY PART NO. DESCRIPTION

Table 8-5. Communication Board Options

PART NUMBER DESCRIPTION

8.4 RECOMMENDED SPARE PARTS

AERCO recommends the DW-Series Spare Parts listed in Table 8-6.

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HE-111 − CORRECTIVE MAINTENANCE

8-26

89011-1

PUMP FLANGE GASKET SET

89011-2

PUMP CASING O-RING

89011-3

PUMP CAPACITOR

89011-5

PUMP CARTRIDGE ASSEMBLY

PART NUMBER (Valve Size)

1″

1¼″

1½″

2″

2½″

3″

4″

ASSEMBLY GASKET

LOWER PILOT SEAT ASSEMBLY

121505

N/A

Table 8-6. Recommended Spare Parts

ITEM QTY PART NO. DESCRIPTION Recommended Emergency Spare Parts

1 2 3 4 5 6 7 8 9

Spare Parts Recommended for Pump Maintenance

12 13 14 15

Spare Parts Recommended for Control Valve Maintenance

ITEM DESC RIPTION

123196-24 DW24 GASKET KIT

123196-45 DW45 GASKET KIT

123196-68 DW68 GASKET KIT

69101 CIRCULATOR PUMP

69009 VALVE ACTUATOR

122770 VACUUM BR EA KE R

64028-12 TEMPERATURE CONTROLLER

99042-1 DOMESTIC WATER INLET THERMOCOUPLE

99042-2 DOMESTIC WATER OUTLET THERMOCOUPLE

1 1 1 1

16 17 18

Optional Spare Parts ITEM QTY PART NO.

21 1 64007 Over-temperature Switch 22 1 65006 Power Su pp ly 24VDC Out p ut 23 1 64011 Voltag e Regu lator 12 VDC O utput

DISC/VALVE SEAT 121541 121527 121510 121531 121935 122032 122178 VALVE TOP GASKET 122136 122136 122136 122136 122083 122204 122203 PACKING ASSEM BL Y 121567 121567 121567 121567 121567 121568 121568 ACTUATOR/LINKAGE

81046 81046 81046 81046 81046 81046 81046

DESCRIPTION

Rev B Mar 2013

9-1

CHAPTER 9 DISASSEMBLY AND REASSEMBLY

9.1 INTRODUCTION

This chapter tells you how to disassemble your DW-Series heat exchanger, check it for tubing leaks, reassemble it and put it back into service.

9.1.1 Tools required

• Torque wrench for 5/8" nuts

• Block and tackle or ratc het or winch ho ist (for lift ing the heat exchan ger u pper head ass embly and

shell, or for lifting and moving the heat exchang er)

9.2 CHECKING FOR A TUBING LEAK

To check for a tube leak:

1. Shut down and drain the heat exchanger in accordance with 6.4.1, Steps 1 through 5.

2. Open the stop valves in the Steam Input line to introduce steam into the heat exchanger tubes.

3. If there is no flow from the leak detection tube ― whereas there had been a flow when the heat

exchanger was in operat io n ― the leak or leaks ar e in the outer wal l (or walls) of the tubi ng. Similarly, if ther e is a flow fr om the leak detec tion tube, the leak or leaks are in the ins ide wall (or walls) of the tubing. When either t ype of leak occurs, it will be nec essary to return the U-bend tube ass embly or the entire heat exchanger to AERCO for repair.

Step 12 explains how to disassemble the U-bend tube assembly from the heat exchanger, and step 14 explains how to obtain instructions for returning equipment to AERCO for repair.

9.3 REMOVING THE HEAT EXCHANGER SHELL

Normally, there is no reas on for the heat exchanger shell to be rem oved. However, if a leak has been detected in the heat exchanger tubing, and it has been determined to be in the outer tubing walls (per section 9.3, step 3), or if there is other valid justification for doing so, the heat exchanger shell may be removed as follows:

1. If the heat exchanger has not alread y been shut down and drained, shut down and drain the heat exchanger in accordance w ith 6.4.1, Steps 1 through 5.

Please refer to Figure 9-1.

2. Disconnect ALL EXTERNAL PIPING from the h eat exchanger upp er head assembly, including th e piping to th e rel ief valv e (1) and the water solenoid valve (2). Disconnec t the Ho t W ater Output piping (not shown) at the union or flange located be yond the outside diam eter of the he at exchanger upper head assembly.

3. Disconnect the Cold Water Input piping from the heat e x changer inlet pipe.

4. Disconnect any power supply wiring to the heat exchanger Control Box (4).

5. Disconnect the pressure gauge (5) from the Steam Input flanges (6).

6. Disconnect recirculation piping (7) at unions 26 and 27.

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HE-111 − DISASSEMBLY AND REASSEMBLY

9-2

"A"

VIEW A-A

"A"

1918

180°

25 23

FOR DW-45 FOR DW-24

& DW-68

Figure 9-1. Typical DW-Series Heat Exchanger

Rev B Mar 2013

HE-111 − DISASSEMBLY AND REASSEMBLY

9-3

7. Mark the edge of the heat exchanger lower head assembly flanges (8) in order to indicate their correct relative positions for reassembly.

8. Remove nuts (9) and studs (10) from the heat exchanger lower head assembly flanges.

9. Using a hois t or block and tac kle attached to the lifting lugs (11) on the heat exchanger upper head assembly, CAREFU LLY lift the u pper head assem bly (12) and shell (13) STRAI GHT UP off the heat exchanger U-bend tubing assembly. AVOID SCR A PING THE SHELL AGAINST THE TUBING (14).

10. Clean and inspect the inside of the shell and the U-bend tubing assembly for obvious damage.

11. If a leak in the tubing has been detected (see steps 1 through 4) and it has been determ ined that t he leak is in the outside wall of one or m ore of the doub le-wall tubes, the le ak ma y be found either by a thorough inspection or as follows:

a. Connect a source of cold water to the leak detection port (15). b. Turn the water on and locate the source of the leak or leaks. c. You may either reassemble the heat exchanger and return it in its entirety to AERCO for

repair, or remove the U-bend tubing assembly and return only that assembl y to AERCO for repair. See step 14 for equipment return information.

12. To disassemble the U-bend tubing assembly (14) from the heat exchanger, remove nuts (9) and studs (10) and lift the assembly off the manifold and skid assembly (16).

13. If for any reaso n it is necessary to rem ove the heat exchanger upper head assembly (12) from the shell (13):

a. Remove the thermocouple (17) from its location in the heat exchanger upper head assembly. b. Remove all connecting wiring, if any, from the heat exchanger upper head assembly. c. Remove all piping and wiring to the relief valve (1) and water Solenoid Valve (2). d. Remove the nuts (18), studs (19), and lifting lugs (11). e. Lift the upper head assembly off the shell.

14. If the heat exch anger or any of its ass emblies are to be returned to the AERCO factory for repair, consult AERCO or your nearest AERCO sales representative for instructions.

CAUTION

Inspect and replace any lugs, nuts and studs that show signs of corrosion with new properly rated hard war e.

9.4 REASSEMBLING THE HEAT EXCHANGER

1. BEFORE REASSEMBLI NG, CLEAN ALL GASKET SU RFACES THO ROUGHLY, using a wire brush or emery cloth, if necessary. ALWAYS USE NEW GASKETS in a reassembly.

2. If the heat exchanger U-bend tubing assembly (14) must be reassembled onto the manifold and skid assembly (16), then proceed as follows:

a. Place a lower tubesheet release gasket (20), a lower t ubesheet gasket ( 21), and a second lower

tubesheet release gasket (ALL NEW) onto the manifold flange (22).

b. Lower the U-bend tubing assembly over the four studs in the manifold flange and onto the

manifold gaskets , making sure the bottom flange of the U-bend assem bly seats onto the locating pin in the top surface of the manifold flange, and that the U-bend assembly is lined up for insertion of the studs through the flanges.

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HE-111 − DISASSEMBLY AND REASSEMBLY

9-4

3. To replace the heat exchanger shell (13) on a DW-45 heat exchanger, skip the rest of this step and all of step 4 and proceed to step 5. For DW-24 and DW-68 heat exchangers, proceed as follows:

a. Place a Teflon upper tubesheet release gasket (24), the shell gasket (23) and another upper

tubesheet release gasket (ALL NEW) onto the U-bend assembly flange.

b. Using a hoist or block and tackle attached to the lifting l ugs (11) on the heat exchanger upp er

head assembly (or to bolt holes in the shell top flange, if the upper head assembly has been removed), CAREFULLY l ower the upper head assembly and she ll STRAIGHT DOWN over the U-bend tubing assembly (14). DO NOT SCRAPE THE SHELL AGAINST THE TUBING.

c. Make sure that the s hell is positioned properly by lining up the marking you put on th e edges of

the flanges in 9.3, step 7.

d. Assemble the studs (10) an d nuts (9) into the m anif old, U-bend as sem bl y flange and s hell flang e.

Cross-tighten the nuts to a pproximatel y 75 foot-pounds of torque to obtain unif orm seating. Then progressively tighten the nuts to approximately 150 foot-pounds of torque for a tight seat.

4. If the heat exchanger upper head assembly (12) has been removed from the shell (13): a. Place a NEW shell gasket (23) onto the gasket surface of the shell top flange. b. Replace the heat exchanger upper hea d assembl y onto the shell top flange mak ing sure that the

stud holes line up.

c. Reassemble the studs, lifti ng lugs ( 11), and n uts ( 18) into the he ad and shel l flan ges. T ighte n the

nuts in the same manner as outlined in step 3d above.

d. Replace the water solenoid valve ( 2), the r elief valve ( 1), and all p iping. Rec onne ct all co nnect ing

wiring, if any, requ ired for accessories on the upper head assembl y. Replace the therm ocouple into their proper locations in the upper head assembly.

Continue assembling the heat exchanger at step 7.

5. If you are replacing the heat exchanger shell (13) on a DW -45 heat exchanger, proceed as follows: a. Place an upper tubesheet release gasket, the lower shell gasket (23) and another upper

tubesheet release gasket (24) (ALL NEW) onto the U-bend assembly flange.

b. Using a hoist or block and tackle attached to the lifting l ugs (11) on the heat exchanger upper

head assembly (or to bolt holes in the shell top flange, if the upper head assembly has been removed), CAREFULL Y lower the upper head assembl y and shell STRAIGHT DOWN over the U-bend tubing assembly (14). DO NOT SCRAPE THE SHELL AGAINST THE TUBING.

c. Make sure that the s hell is positioned properly by lining up the marking you put on th e edges of

the flanges in 9.3, step 7.

d. Assemble the studs (10) and nuts ( 9) into the manifold, U-bend assembly flange and shell flange.

Cross-tighten the nuts to a pproximatel y 75 foot-pounds of torque to obtain unif orm seating. Then progressively tighten the nuts to approximately 150 foot-pounds of torque for a tight seat.

6. If the heat exchanger upper head assembly (12) has been removed from the shell (13): a. Place a NEW upper shell gasket (25) onto the gasket surface of the shell top flange. b. Replace the heat exchanger upper hea d assembl y onto the shell top flange mak ing sure that the

stud holes line up.

Rev B Mar 2013

HE-111 − DISASSEMBLY AND REASSEMBLY

9-5

c. Reassemble the studs, lifti ng lugs ( 11), and n uts (18) into the he ad and shell f lan ges. T ighten th e

nuts in the same manner as outlined in step 3d above.

d. Replace the water solenoid valve (2), if any, the relief valve (1), and all piping. Reconnect all

connecting wiring, if any, required for accessories on the upper head assembly. Replace the thermocouple into its proper locations in the upper head assembly.

7. Reinstall the circulation piping.

8. Reconnect the pressure gauge to the Steam Input flange.

9. Reconnect any power supply wiring to the heat exchanger Control Box, and reconnect any wiring between the Control Box and any solenoid valves included in the system.

10. Reconnect all external piping to the heat exchanger upper head assembly, including the piping to the relief valve (1) and the water solenoid valve (2).

11. Refill and put the heat exchanger back into service in accor dance wit h 5.3, steps 1 through 15.

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9-6

This page intentionally left blank.

Rev B Mar 2013

APPENDIX A

CONTROL AND COMMUNICATION

A.1 TEMPERATURE CONTROLLER PROCEDURES

A.2 MODBUS COMMUNICATION INFORMATION

A.3 PROCESS / DIAGNOSTIC ALARM MESSAGES

HE-111 − APPENDIX A

A-2

COMMUNICATIONS

LATCHING

A.1 TEMPERATURE CONTROLLER PROCEDURES A.1.1 Adding a Communication Board to the Temperature Controller A.1.1.1 Parts Needed

1. Control Box Assembly ECS, P/N: 69012-[ ]

2. Temperature Indicating Controller, P/N: 64008

3. Communications Board, P/N: 64009-[ ]

A.1.1.2 Procedure for Adding the Communication Board

1. Turn off power to Control Box Assembly ECS (P/N 69012-[ ])

2. Slide out Temperature Indicating Cont ro ller ( P/N : 640 08) f rom C ontrol Box Ass e mbly by gently pushing the indicated latchi ng ears to the side (See Figure 1).

EARS (2)

Figure 1

3. Slide Communications Boar d (P/N 64009-[ ]) into Tem perature Indicating Contr oller slot (COMMS 1). See Figure 2. Make sure to pus h Communications Board all the way in to ensure it is f irmly seated in its slot.

BOARD

Figure 2

Rev B Mar 2013

HE-111 − APPENDIX A

A-3

Scroll

Page

Up/Down Arrow

4. Place Temperature Indicating Controller back into Control Box Assembly and power up unit. The following screen will appear. (See Figure 3)

Button

Keys

Button

Figure 3

5. The Controller will report a hardware err or as ind icat e d on Figure 3. Press the ▲(up) arrow key located on the right side of the Temperature Controller until “8” appears on the lower half of the screen.

6. Press the page button located on the left side of the Temperature Indicating Controller until “Exit” appears on the top half of the screen.

7. Press the ▲ / ▼ (up/down) arrow key to choose “yes”.

8. Wait a moment as the screen updates. The hardware error will no longer be displayed.

9. This completes installation of the Communications Board.

Rev B Mar 2013

HE-111 − APPENDIX A

A-4

Button Map

Page

Up Arrow

A.1.2 Changing the Temperature Controller Communication Addresses

NOTE

Refer to the button map at the bottom of the display for all panel navigation instructions.

Scroll

Down Arrow

The Temperature Contr oller address is def aulted to 1 from the factory. To change the MODBUS address, proceed as follows:

1. Page to the ACCS list and Scroll down to codE.

Rev B Mar 2013

A-5

2. Enter 24 using the Up Ar r ow. The number will flash and display PASS.

3. Scroll to Goto (current value is OPEr) and use the Down Arrow to enter a value of Full. The entry confirms by flashing the lower display momentarily off and then on.

4. Go to the home screen by pressing the Page and Scroll buttons at the same time.

HE-111 − APPENDIX A

5. Page to the cmS list.

6. Scroll to the Addr screen.

7. Use the Up Arrow to select the desired address number.

Rev B Mar 2013

HE-111 − APPENDIX A

A-6

8. Go to the home screen by pressing the Page and Scroll buttons at the same time.

9. Page to the ACCS list and change the code to anything other than 24. The codE number you enter will flash off and then on to 0 to confirm that access is now set to the OPEr level and it is safe to return to use.

10. Confirm that the Addr is set properly by pressing the Page button until the cmS list is displayed. Scroll to Addr. If the value is correct you are done; if not, repeat the steps in this procedure.

Rev B Mar 2013

A-7

A.2 MODBUS COMMUNICATION INFORMATION

Address

Item

Description

Range

Default/Comments

Type

Guide

Only

SP 1

Setpoint

40-180°F

140°F, Address to change value

Write

5-11

Value

Only

Temp

Only

1 = alarm)

1= alarm)

1: Failed

Sensor Temp

as display temp.

Only

Signal

address

NOTE

The Eurotherm 2400 Controller supports the MODBUS RTU mode of transmission. The default settings are as follows: 9600 Baud Rate, one start bit, eight data bits, one stop bit and no parity bit.

Table A-1. Eurotherm Series 2400 Controller MODBUS Points

HE-111 − APPENDIX A

MODBUS

Data

5 w.SP Setpoint 40-205°F 140°F, Address to read value Read

1 Top

133 LoGH Peak Temp 40-205°F Resets on Power Loss Read

135 LoGA Average

134 LoGL Low Temp 40-205°F Resets on Power Loss Read

13 (set) 74 (status, 0 = safe

14 (set) 74 (status, 0 = safe

Outlet Temp 40-205°F Same value as front display Read

AL 1 Over Temp

Alarm

AL 2 (FSH)

Full Scale High Alarm

Menu Item

Units &

40-205°F Resets on Power Loss Read

40-205°F 20°F above setpoint; Alarm Type

17: Deviation High

205°F 205 ° F

Alarm Type 2: Full Scale High

Read Only

Ref. 1

Comm.

5-4

5-3

5-15

5-7 5-20

258 Sbr Feedback

Sensor Break

289 Li 1 Feedback

290 Li 2 Flow GPM Read

3 OP Control

Output

131 Addr Communicati

on Address

Status: 0: Good

40-180°F Sensor input to controller, same

% Correlates to valve position Read

Integer (0-63)

Denotes Feedback Sensor Failure/Open Circuit

Default – 1. Temperature Controller communication

Read Only

Read

Only

Read Only

5-18

5-14

5-4

5-14

REFERENCE DOCUMENTS

1. Eurotherm 2000 Series Communications Handbook, # HA026230

2. Eurotherm 2404/2408 Control Setpoint Programmer Installation and Operation Handbook,

# HA025132

Rev B Mar 2013

HE-111 − APPENDIX A

A-8

DISPLAY

MEANING

_FSL*

PV Full Scale Low Alarm.

_FSH*

PV Full Scale High Alarm.

_dEu*

PV Deviation Band Alarm

_dHi*

PV Deviation Hig h A lar m

_dLo*

PV Deviation Low Alarm

DISPLAY

MEANING

WHAT TO DO

EE.Er

Electrically Erasable Memory Error:

This fault will automaticall y tak e you into

frequently, contact your supplier

S.br

Sensor Break: Input sensor is of range.

Check that the sensor is correctly connected

Hw.Er

Hardware Error wrong type, missing, or faulty.

Check to ensure that the correct items are installed. See

no.io

No I/O installed.

This error message normally occurs when pre-configuring

rmt.F

shorted.

LLLL

Out of range low reading

Check the value of the input

HHHH

Out of range high reading

Check the value of the input

Err1

Error 1: ROM self-test fail

Return Controller for repair

A.3 PROCESS AND DIAGNOSTIC ALAR MS A.3.1 Process Alarms

The following are the process alarms that can appear on the Temperature Controller display.

Table A-2. Process Alarms

A.3.2 Diagnostic Alarms

The following are the diagnostic alarms that can appear on the Temperature Controller display.

Table A-3. Diagnostic Alarms

The value of an operator, or configuration, parameter has been corrupted.

unreliable or the input signal is out

Indication that a module is of the

None of the expected I/O items are

Remote input failure. The remote DC input is open or

Configuration level. Check all of the configuration parameters before returning to Operator level. Once in Operator level, check all of the operator parameters before resuming normal operation. If the fault persists, or occurs

A.3.3 for procedure to clear the hardware error.

a controller without installing any of the required I/O modules.

Check for open or short circuit wiring on the remote DC input.

Rev B Mar 2013

HE-111 − APPENDIX A

A-9

DISPLAY

MEANING

WHAT TO DO

Err2

Error 2: RAM self-test fail

Return Controller for repair

Err3

Error 3: Watchdog fail

Return Controller for repair.

during power-up

communication

cannot be cleared, return the controller for repair.

board inside controller

Err7

PV ID failure

Return Controller for repair

Err8

Module 1 ID failure

Faulty or loose module, or isolation problem

Err9

Module 2 ID failure

Faulty or loose module, or isolation problem

ErrA

Module 3 ID failure

Faulty or loose module, or isolation problem

dCF

DC output failure

Return Controller for repair.

feedforward sensor and the Eurotherm controller.

Table A-3. Diagnostic Alarms - continued

Err4

Error 4: Keyboard failure. Stuck button or button was pressed

Err5

Err6

OPEn

Error 5: Faulty internal

Digital filter chip faulty or loose

Secondary Input Missing or Disconnected

A.3.3 Clearing the Hardware Error Display

Switch power off and then on, without touching any of the controller buttons

Check printed circuit board interconnections. If the fault

Return Controller for repair

This error may result from no power to the flow meter (check for green power light on rear of meter or 0-5V flow meter signal connections), or a disconnection of the Molex connector between

To clear a hardware error (HW.ER) and reset the Temperature Controller, proceed as follows:

1. Simultaneously press the Page ( ) and Scroll ( ) buttons on the Temperature Controller.

2. Using the Up (▲) arrow button, change the password to “8”.

3. Simultaneously press the Page ( ) and Scroll ( ) buttons again and observe the Temperature

Controller display. The top line will display “8” and the bottom line will display “NO”.

4. Press the Up (▲) arrow button to toggle the display from “NO” to “YES”.

5. Simultaneously press the Page ( ) and Scroll ( ) buttons to “Reset” the Temperature

Controller and clear the hardware error.

Rev B Mar 2013

HE-111 − APPENDIX A

A-10

This page intentionally left blank.

Rev B Mar 2013

APPENDIX B

B.1 WIRING DI AGRAMS

B.2 TERMINAL BLOCK CONNECTIONS

HE-111 − APPENDIX B

B-2

INPUT 1

INPUT 2

THERMOCOUPLE

WHITE

RED

120/240VAC

THERMO COUPLE

(OUTLET)

POWER SWITCH

POWER IN 120 VAC

109 11

PROBE INPUT

POWER SUPPLY 12VDC

NC NOCOM

THERMOCOUPLE

(OUTLET)

SOLENOID

VALVE

LINE

NEUTRAL

GROUND

OVER TEMPERATURE SWITCH

LINE

POWER SUPPLY

INPUT 120 VAC OUTPUT 24VDC

+V +V

-V

NEUTRAL

LINE

RED

WHITE

NEUTRAL

GROUND

VOLTAGE REGULATOR

INPUT 24VDC OUTPUT 12VDC

LM 7812

INPUT OUTPUT

260 V, 2A RELAY

101

100

101

102

GND

103

104

TB-1

104

105

TB-1

112

111

TB-2

102

100

102

TB-2

GND

104

107

TB-1

105

104

106

114

104

TB-1

109

110

106

107

TB-2

103

100

102

(FEEDBACK)

113 + 113

MIXED INLET TEMPERATURE THERMOCOUPLE

INTERNAL RECIRCULATION PUMP

GND

100

102

GND

TB-2

FLEX CONDUIT

ACTUATOR

TB-1

COMMON

24VDC

RESET BUTTON

DIP SWITCH

4-20 MA

120 VAC, 60 HZ

J THERMOCOUPLE MIXED

105

100

V+

V-

C O

TEMPERATURE CONTROLLER

SEE TABLE 1

104

TABLE 1

TEMP CONTROLLER

SIGNAL NAME PIN NO.

GROUND HD

RECEIVE

TRANSMIT HF

COMPUTER CONTROL CABLE

SIGNAL NAME

GROUND TRANSMIT

PIN NO.

2 3

PIN NO.

A B

GROUND

PIN NO.

RS-232 / 9 PIN

RS-232 / 25 PIN RS-485

RECEIVE

102

100

102

(LOCATED AT INLET)

106

Rev B Mar 2013

NOTE: This drawing is only applicable for ol der units built WITH the voltage regulat or, which are thos e units with a serial number BEFORE H-10-324.

Figure B-1a. DW-Series Heat Exchanger Wiring Diagram (S/N H-10-323 and Below)

HE-111 APPENDIX B

B-3

NOTE: This drawing is only applicable for newer units buil t WITHOUT the voltage regulator, which are those units with a serial number of H-10-325 and ABOVE.

Figure B-1b. DW-Series Heat Exchanger Wiring Diagram (S/N H-10-325 and Above)

Rev B Mar 2013

HE-111 − APPENDIX B

B-4

103

104

110

111

112

114

106

104

109

SOLENOID

FEEDBACK (TC -)

OVER-TEMP (TC +)

OVER-TEMP (TC -)

ACTUATOR (4 – 20 mA)

ACTUATOR (+24 VDC)

ACTUATOR (COM)

FEEDBACK (TC +)

WIRE NUMBERS

FUNCTIONS

TERMINAL BLOCK TB-1 (REAR WALL)

113

105

104

107

104

MIXED INLET (TC+/-)

ACTUATOR (COM)

OVER-TEMP (+24

VDC)

OVER-TEMP (+12 VDC)

100

NEUTRAL

101

102

GROUND

LINE

TERMINAL BLOCK TB-2

(BOTTOM SURFACE )

Figure B-2. Terminal Block TB-1 Connections

Figure B-3. Terminal Block TB-2 Connections

Rev B Mar 2013

AERCO DW User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Telephone Support

CHAPTER 1 GENERAL INFORMATION

1.1 INTRODUCTION

1.2 MECHANICAL OVERVIEW

1.3 ELECTRONIC CONTROL SYSTEM

1.4 OPTIONS AND ACCESSORIES

1.4.1 MODBUS Communication Option

1.4.2 Accessories

CHAPTER 2 INSTALLATION

2.1 INTRODUCTION

2.2 RECEIVING, UNPACKING AND INSTALLING

2.3 MAKING THE PIPING CONNECTIONS

2.4 INSTALLING THE CXT-E ELECTRONIC CONTROL SYSTEM

2.4.1 Accessing the Control Box Interior

2.4.2 Connecting AC Power to the Control Box

2.4.3 Wiring the CXT-E Actuator

2.4.4 Verifying Pre-wired Connections

2.4.5 Wiring the Temperature Controller to the MODBUS Control System

2.4.6 Control System Programming Information

CHAPTER 3 FUNCTIONAL DESCRIPTION

3.1 INTRODUCTION

3.2 MECHANICAL DESCRIPTION

3.2.1 Overview

3.2.2 Double-Wall Heat Transfer and Water Leakage

3.2.3 Principal Mechanical Components

3.2.3.1 Shell and Heads

3.2.3.2 Double-Wall U-Tube Bundle and Tubesheets

3.2.3.3 Recirculation Pipe and Pump

3.2.3.4 CXT-E Control Val ve

3.3 ELECTRONIC CONTROL SYSTEM

3.3.1 ECS Block Diagram

3.3.2 ECS Operational Summary

3.3.3 Over-temperature Condition

3.3.4 Principal ECS Components

3.3.4.1 Control Box Assembly

3.3.4.2 DHW Outlet Dual Temperature Sensor

3.3.4.3 Feed-Forward Mixture Temperature Sensor

3.3.4.4 Over-temperature Solenoid Valve

3.3.4.5 Electronic CXT-E Control Valve Actuator

CHAPTER 4 ADJUSTMENT

4.1 INTRODUCTION

4.2 ADJUSTING THE ELECTRONIC CXT-E ACTUATOR

4.3 ADJUSTING THE ELECTRONIC CONTROL SYSTEM

4.3.1 Adjusting the Setpoint Temperature

4.3.2 Adjusting the Over-Temperature Alarm Limit

CHAPTER 5 OPERATION

5.1 INTRODUCTION

5.2 PRE-OPERATIONAL

5.3 STARTUP PROCEDURES

5.4 SHUTTING DOWN AND DRAINING THE HEAT EXCHANGER

CHAPTER 6 SCHEDULED MAINTENANCE

6.1 INTRODUCTION

6.2 WEEKLY MAINTENANCE

6.3 MONTHLY MAINTENANCE

6.4 QUARTERLY MAINTENANCE

6.4.1 First Three Months

6.4.2 Each Quarter

6.5 SEMI-ANNUAL MAINTENANCE

6.6 ANNUAL MAINTENANCE

CHAPTER 7 TROUBLESHOOTING

7.1 INTRODUCTION

1. ELECTRONIC CONTROL VALVE, CXT-E a. Verif y that all piping conne ctions have been made in accordanc e with Figure 2-4 and that all

2. ELECTRONIC CONTROL SYSTEM

7.2 TROUBLESHOOTING PROCEDURES

1. Refer to the FAULT INDICATION column in the following tables and locate the fault that best describes the existing conditions.

2. Proceed to the PROBABLE CA USE column. If m ore than one item is listed, start with the f irst item shown for the fault condition.

3. Perform the corresponding check s and proc edures list ed in the C ORRECT IVE A CT ION colum n for the first PROBABLE CAUSE.

4. Continue checking each additio nal PROBABLE CAUSE for the existing fault u ntil the fault has been corrected.

5. If component removal and /or replacem ent is required, refer to the appl icable procedures in Chapter 8 Corrective Maintenance.

CHAPTER 8 CORRECTIVE MAINTENANCE

8.1 INTRODUCTION

8.2 CXT-E ELECTRONIC CONTROL VALVE

8.2.1 Valve Shaft Seal Retainer Replacement

8.2.2 Valve Disassembly

8.2.3 Valve Reassembly

8.2.4 Actuator Replacement