AERCO DW User Manual
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
2
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
© AERCO International, Inc., 2009
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
iv
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
v
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
vi
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:
Rev B Mar 2013
HE-111 − GENERAL INFORMATION
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.
Rev B Mar 2013
HE-111 − GENERAL INFORMATION
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.
Rev B Mar 2013
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
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
No
• Suggested for ease of maintenance
•
Required
Recommended for adjustment and
maintenance
Recommended for adjustment and
maintenance.
Rev B Mar 2013
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.
Rev B Mar 2013
HE-111 − INSTALLATION
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
Rev B Mar 2013
HE-111 − INSTALLATION
2-3
AERCO
*
1
0
9
0
0
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
Rev B Mar 2013
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.
Rev B Mar 2013
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.
Rev B Mar 2013
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).
Rev B Mar 2013
HE-111 − INSTALLATION
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
TM
Figure 2-6. Recessed Panel Behind Control Box Door
2.4.2 Connecting AC Power to the Control Box
PT.NO.
F
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.
Rev B Mar 2013
HE-111 − INSTALLATION
2-9
2408 TEMP. CONTROLLER
COMPUTER CONTROL CABLE
RS232 9-PIN
RS232 25-PIN
RS485
SIGNAL NAME
TERMINAL
SIGNAL NAME
PIN NO.
PIN NO.
PIN NO.
GROUND
HD
GROUND 5 7
GROUND
RECEIVE
HE
TRANSMIT
3 2 A(-)
TRANSMIT
HF
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
1A
HA
1B
HB
1C
HC
2A
2B
1D
HE
HF
HD
3B
3D
3C
2D
3A
2C
JD
JF
JE
JB
JC
JA
LA
LB
LC
AA
AB
AC
VI
V+
V-
Input 1
C
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.
Rev B Mar 2013
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
Rev B Mar 2013
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)
Rev B Mar 2013
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.
Rev B Mar 2013
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
Rev B Mar 2013
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.
Rev B Mar 2013
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.
Rev B Mar 2013
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.
Rev B Mar 2013
HE–111− FUNCTIONAL DESCRIPTION
3-8
A
B
C
D
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”
2
1.25” and 2.5”
3
1.5” and 3”
4
2” and 4”
0
90
neptronic
1 2 3
1 2
3
4 5
1
2
3
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
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