AERCO BMK 1.5 LN User Manual May 2009
AERCO INTERNATIONAL, Inc., Northvale, New Jersey, 07647 USA
Instruction
No.
GF-120
Installation, Operation
& Maintenance Instructions
Benchmark 1.5LN
Series
Gas Fired
Low NOx
Boiler System
Condensing, Modulating
Forced Draft, Hot Water Boiler
1,500,000 BTU/H Input
Printed in U.S.A. REVISED MAY, 2009
Telephone Support
Direct to AERCO Technical Support
(8 to 5 pm EST, Monday through Friday):
1-800-526-0288
AERCO International, Inc.
159 Paris Avenue
Northvale, NJ 07647-0128
www.aerco,com
© AERCO International, Inc., 2009
The information contained in this
installation, operation and maintenance manual is subject to
change without notice from
AERCO International, Inc.
AERCO makes no warranty of any
kind with respect to this material,
including but not limited to implied
warranties of merchantability and
fitness for a particular application.
AERCO International is not liable
for errors appearing in this
manual. Nor for incidental or
consequential damages occurring
in connection with the furnishing,
performance, or use of this
material.
CONTENTS
GF-120 - AERCO BENCHMARK 1.5LN GAS FIRED LOW NOx BOILER
Operating & Maintenance Instructions
FOREWARD A
Chapter 1 – SAFETY PRECAUTIONS 1-1
Para. Subject Page
1-1 Warnings & Cautions 1-1
1-2 Emergency Shutdown 1-2
Chapter 2 – INSTALLATION 2-1
Para. Subject Page
2.1 Introduction 2-1
2.2 Receiving the Unit 2-1
2.3 Unpacking 2-1
2.4 Site Preparation 2-1
2.5 Supply and Return Piping 2-3
2.6 Condensate Drains 2-3
2.7 Gas Supply Piping 2-4
2.8 AC Electrical Power Wiring 2-5
Para. Subject Page
1-3 Prolonged Shutdown 1-2
Para. Subject Page
2.9 Modes of Operation and Field
Control Wiring
2.10 I/O Box Connections 2-7
2.11 Auxiliary Relay Contacts 2-9
2.12 Flue Gas Vent Installation 2-9
2.13 Combustion Air 2-9
2-5
Chapter 3 – CONTROL PANEL COMPONENTS AND
OPERATING PROCEDURES 3-1
Para. Subject Page
3.1 Introduction 3-1
3.2 Control Panel Description 3-1
3.3 Control Panel Menus 3-4
3.4 Operating Menu 3-5
3.5 Setup Menu 3-5
Para. Subject Page
3.6 Configuration Menu 3-6
3.7 Tuning Menu 3-7
3.8 Start Sequence 3-7
3.9 Start/Stop Levels 3-9
Chapter 4 – INITIAL START-UP 4-1
Para. Subject Page
4.1 Initial Startup Requirements 4-1
4.2 Tools and Instruments for
Combustion Calibration
4.3 Natural Gas Combustion
Calibration
4-1
4-2
Para. Subject Page
4.4 Unit Reassembly 4-5
4.5 Over-Temperature Limit
Switches
4-5
i
CONTENTS
Chapter 5 – MODE OF OPERATION 5-1
Para. Subject Page
5.1 Introduction 5-1
5.2 Indoor/Outdoor Reset Mode 5-1
5.3 Constant Setpoint Mode 5-2
5.4 Remote Setpoint Mode 5-2
5.5 Direct Drive Modes 5-3
Para. Subject Page
5.6 Boiler Management System
(BMS)
5.7 Combination Control System
(CCS)
5-4
5-5
Chapter 6 – SAFETY DEVICE TESTING PROCEDURES 6-1
Para. Subject Page
6.1 Testing of Safety Devices 6-1
6.2 Low Gas Pressure Fault Test 6-1
6.3 High Gas Pressure Test 6-2
6.4 Low Water Level Fault Test 6-2
6.5 Water Temperature Fault Test 6-2
6.6 Interlock Tests 6-3
6.7 Flame Fault Test 6-4
Para. Subject Page
6.8 Air Flow Fault Test 6-4
6.9 SSOV Proof of Closure Switch 6-4
6.10 Purge Switch Open During
Purge
6.11 Ignition Switch Open During
Ignition
6.12 Safety Pressure Relief Valve
Test
6-5
6-5
6-6
Chapter 7 – MAINTENANCE REQUIREMENTS 7-1
Para. Subject Page
7.1 Maintenance Schedule 7-1
7.2 Spark Ignitor 7-1
7.3 Flame Detector 7-2
7.4 Combustion Calibration 7-2
7.5 Safety Device Testing 7-3
7.6 Burner Assembly 7-3
Para. Subject Page
7.7 Condensate Drain Trap 7-4
7.8 Shutting the Boiler Down For An
Extended Period of Time
7.9 Placing The Boiler Back In
Service After A Prolonged
Shutdown
7-4
7-4
Chapter 8 – TROUBLESHOOTING GUIDE 8-1
Para. Subject Page
8.1 Introduction 8-1
Para. Subject Page
ii
CONTENTS
APPENDICES
App Subject Page
A Boiler Menu Item Descriptions A-1
B Startup, Status and Fault
Messages
C Temperature Sensor Resistance
Chart
D Indoor/Outdoor Reset Ratio
Charts
B-1
C-1
D-1
WARRANTIES W-1
App Subject Page
E Boiler Default Settings E-1
F Dimensional and Part Drawings F-1
G Piping Drawings G-1
H Wiring Schematics H-1
I Recommended Periodic Testing
Checklist
J Benchmark Control Panel Views J-1
I-1
iii
FOREWORD
Foreword
The AERCO Benchmark 1. 5LN Boiler is a m odulating unit. It represents a true industry advance
that meets the needs of today's ener gy and environmental concerns. Designed for application
in any closed loop hydronic system, the Benchmark's modulating capability relates energ y input
directly to fluctuating system loads. The Benchmark 1.5, with its 20:1 turn down ratio and
condensing capability, provides extremely high efficiencies and makes it ideally suited for
modern low temperature, as well as, conventional heating systems.
The Benchmark 1.5 operates at inputs ranging from 75, 000 BTU/hr. to 1,500,000 BTU/hr. The
output of the boiler is a f unction of the unit’s firing rate and return water temperat ure. Output
ranges from 74,250 BT U/hr. to 1,450,000 BTU/hr . , depending on operating conditions.
When installed and operated in accordance with this Instruction Manual, the Benchmark 1.5
Boiler complies with the NOx emission standards outlined in:
• South Coast Air Quality Management District (SCAQMD), Rule 1146.2
Whether used in singular or modular arrangements, the Benchmark 1.5 offers the maximum
flexibility in venting with minimum installation space requirements. The Benchmark 's advanced
electronics are available in several selectable modes of operation offering the most efficient
operating methods and energy manag em ent system integration.
For service or parts, contact your local sales represent at ive or AERCO I NTERNATIONAL.
NAME:
ORGANIZATION:
ADDRESS:
TELEPHONE:
INSTALLATION DATE: _____________________________________________
A
SAFETY PRECAUTIONS
CHAPTER 1 SAFETY PRECAUTIONS
1.1 WARNINGS & CAUTIONS
Installers and operating personnel MUST, at all
times, observe all safety regulations. The
following warnings and cautions are general and
must be given the same attention as specific
precautions included in these instructions. In
addition to all the requirements included in this
AERCO Instruction Manual, the installation of
units MUST conform with local building codes,
or, in the absence of local codes, ANSI Z223.1
(National Fuel Gas Code Publication No. NFPA-
54). Where ASME CSD-1 is required by local
jurisdiction, the installation must conform to
CSD-1.
Where applicable, the equipment shall be
installed in accordance with the current
Installation Code for Gas Burning Appliances
and Equipment, CGA B149, and applicable
Provincial regulations for the class; which should
be carefully followed in all cases. Authorities
having jurisdiction should be consulted before
installations are made.
IMPORTANT
This Instruction Manual is an integral
part of the product and must be
maintained in legible condition. It must
be given to the user by the installer
and kept in a safe place for future
reference.
WARNINGS!
MUST BE OBSERVED TO PREVENT
SERIOUS INJURY.
WARNING!
BEFORE ATTEMPTING TO PERFORM ANY MAINTENANCE ON THE
UNIT, SHUT OFF ALL GAS AND
ELECTRICAL INPUTS TO THE UNIT.
WARNING
DO NOT USE MATCHES, CANDLES,
FLAMES, OR OTHER SOURCES OF
IGNITION TO CHECK FOR GAS
LEAKS.
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
120 VAC MAY BE USED IN THIS
EQUIPMENT. THEREFORE THE
COVER ON THE UNIT’S POWER
BOX (LOCATED BEHIND THE
FRONT PANEL DOOR) MUST BE
INSTALLED AT ALL TIMES, EXCEPT
DURING MAINTENANCE AND
SERVICING.
CAUTIONS!
Must be observed to prevent
equipment damage or loss of
operating effectiveness.
CAUTION!
Many soaps used for gas pipe leak
testing are corrosive to metals. The
piping must
clean water after leak checks have
been completed.
be rinsed thoroughly with
WARNING!
THE EXHAUST VENT PIPE OF THE
UNIT OPERATES UNDER A
POSITIVE PRESSURE AND THEREFORE MUST BE COMPLETELY
SEALED TO PREVENT LEAKAGE
OF COMBUSTION PRODUCTS INTO
LIVING SPACES.
CAUTION!
DO NOT use this boiler if any part has
been under water. Call a qualified
service technician to inspect and
replace any part that has been under
water.
1-1
SAFETY PRECAUTIONS
1.2 EMERGENCY SHUTDOWN
If overheating occurs or the gas supply fails to
shut off, close the manual gas shutoff valve
(Figure 1-1) located external to the unit.
IMPORTANT
The Installer must identify and indicate
the location of the emergency shutdown
manual gas valve to operating personnel.
1.3 PROLONGED SHUTDOWN
After prolonged shutdown, it is recommended
that the startup procedures in Chapter 4 and the
safety device test procedures in Chapter 6 of
this manual be performed, to verify all systemoperating parameters. If there is an emergency,
turn off the electrical power supply to the
AERCO boiler and close the manual gas valve
located upstream the unit. The installer is to
identify the emergency shut-off device.
Figure 1-1
Manual Gas Shutoff Valve
1-2
INSTALLATION
CHAPTER 2 INSTALLATION
2.1 INTRODUCTION
This Chapter provides the descriptions and
procedures necessary to unpack, inspect and
install the AERCO Bench mark 1.5 Boiler. Brief
descriptions are also pr ovided f or each avai lable
mode of operation. Detailed procedures for
implementing these modes are provided in
Chapter 5.
2.2 RECEIVING THE UNIT
Each Benchmark 1.5 System is shipped as a
single crated unit. The shipping weight is
approximately 1551 pounds. The unit must be
moved with the proper rigging equipment for
safety and to avoid equipment dam age. The unit
should be complete ly inspected for evidence of
shipping damage and ship ment com pleteness at
the time of receipt from the carrier and before
the bill of lading is signed.
NOTE
AERCO is not responsible for lost or
damaged freight.
Each unit has a Tip-N-Tell indicator on the
outside of the crate. T his indic ates if the un it has
been turned on its side during shipment. If the
Tip-N-Tell indicat or is trip ped, do not s ign for the
shipment. Note the information on the carrier’s
paperwork and request a freight claim and
inspection by a claims adjuster before
proceeding. Any other visual damage to the
packaging materials s hould also be made clear
to the delivering carrier.
2.3 UNPACKING
Carefully unpack the unit taking care not to
damage the unit enclosure when cutting away
packaging materials
A close inspection of the unit s hould be made to
ensure that there is no evidence of dam age not
indicated by the T ip-N-Tell indicator. The f reight
carrier should be notified immediately if any
damage is detected.
The following accessories come standard with
each unit and are either packed separately
within the unit’s pack ing container or are fac tory
installed on the boiler:
• Pressure/Temperature Gauge
• Spare Spark Igniter
• Spare Flame Detector
• ASME Pressure Relief Valve
• Condensate Drain Trap
• 1-1/2” Gas Supply Shutoff Valve
When ordered, optional accessories may be
packed separately, packed within the boiler
shipping container, or may be installed on the
boiler. Any standard or optional accessories
shipped loose should b e identified and s tored in
a safe place until ready for installation or use.
2.4 SITE PREPARATION.
Ensure that the site selected for installation of
the Benchmark 1.5 Boiler includes:
• Access to AC Input Power at 120 VAC, 1-
Phase, 60 Hz @ 20
• Access to Natural Gas line at a minimum
pressure of 4 inches W.C.
2.4.1 Installation Clearances
The unit must be installed with the prescribed
clearances for service as shown in Figure 2-1.
The minimum
AERCO, are listed below. However, if Local
Building Codes require additional clearances,
these codes shall supersede AERCO’s
requirements. Minimum acceptable clearances
required are:
• Sides: 24 inches
• Front : 24 inches
• Rear: 30 inches
• Top: 18 inches
All gas piping, water piping and el ec tric al c on du it
or cable must be arranged so that they do not
interfere with the removal of any panels, or
inhibit service or maintenance of the unit.
clearance dimens ions , requir ed by
2-1
INSTALLATION
Figure 2-1 Benchmark 1.5 Boiler Clearances
WARNING
KEEP THE UNIT AREA CLEAR AND
FREE FROM ALL COMBUSTIBLE
MATERIALS AND FLAMMABLE
VAPORS OR LIQUIDS
.
CAUTION
While packaged in the shipping
container, the boiler must be moved
by pallet jack or forklift from the
FRONT ONLY.
2.4.2 Setting the Unit
The unit must be installed on a 4 inch to 6 inch
housekeeping pad to e nsure proper conde nsate
drainage. If anchoring the unit, refer to the
dimensional drawings in Appendix F for anchor
locations. Two lifting t abs ar e provided a t the top
of the heat exchanger as shown in Figure 2-2.
USE THE TABS SHOWN IN FIGURE 2-2 TO
LIFT AND MOVE THE UNIT . Remove the front
top panel from the unit to prov ide access to the
lifting tabs. Remove the four (4) lag screws
securing the unit to the shipping skid. Lift the
unit off the shipping sk id and position it on the 4
inch to 6 inch housekeeping concrete pad
(required) in the desired location.
BLOWER
LIFTING
TAB
AIR/FUEL
VALVE
FRONT
LIFTING
Figure 2-2
Partial Top View Showing Lifting Tab
Locations
In multiple unit installations, it is important to
plan the position of each unit in advance.
Sufficient space for piping connections and
future service/maintenance requirements must
also be taken into cons ider ation. All pipin g m ust
include ample provisions for expansion.
TAB
2-2
If installing a Combina tion Control Panel (CCP)
system, it is important to identify the
Combination Mode B oilers in adv ance and plac e
them in the proper physical location. Refer to
Chapter 5 for inform ation on Combination Mode
Boilers.
2.5 SUPPLY AND RETURN PIPING
The Benchmark 1.5 Boiler utilizes 3” 150#
flanges for the water system supply and return
piping connectio ns. The physical location of the
supply and return p iping connections are on the
rear of the unit as shown in Figure 2-3. Ref er to
Appendix F, Drawing AP-A-832 for additional
dimensional data.
INSTALLATION
Figure 2-4
Condensate Drain Connection Location
2.6.1 Exhaust Manifold Condensate
Drain
The exhaust manifold drain pipe connection
shown in Figure 2-4, must be connected to a
condensate drain trap external to th e unit. Refer
to Figure 2-5 and install the trap as follows:
Figure 2-3
Supply and Return Locations
2.6 CONDENSATE DRAIN
The Benchmark 1.5 Boiler is designed to
condense water vapor from the flue products.
Therefore, the insta llation must have provisions
for suitable condensate drainage or collection.
The drain pipe located on the exhaust manifold
must be connected to a c ondensate trap which
is packed separately within the unit’s shipping
container.
1. Position the supplied condensate trap (part
no. 24060) on the floor at the rear of the
unit.
2. Install 3/4” NPT nipples in the tapped inlet
and outlet of the condensate trap.
3. Attach a length of 1” I.D. hose between t he
exhaust manifold drain pipe and the inlet
side of the condensate trap (Figure 2-5).
Secure both ends of the hose with clamps.
4. Connect a second length of 1” I.D. h ose to
the outlet side of the condensate trap and
route it to a nearby floor drain.
If a floor drain is not available, a condensate
pump can be used to remove the condens ate to
drain. The max imum condensate flow rate is 2 0
GPH. The condensate drain trap, associated
fittings and drain lines must be removable for
routine maintenance. Therefore, DO NOT hard
pipe.
The procedure to install and connect the
condensate drain is provided in paragraph 2.6.1.
2-3
INSTALLATION
Figure 2-5
Condensate Trap Installation
2.7 GAS SUPPLY PIPING
The AERCO Benchmark 1.5 Gas Components
and Supply Design Guide, GF-4030 must be
consulted prior to des ignin g or installi ng an y gas
supply piping.
A suitable piping compound, approved for use
with natural gas, should be used. Any excess
must be wiped off to prevent clogging of
components.
To avoid unit damage whe n pres sur e tes ting gas
piping, isolate the unit from the gas supply
piping. At no time should the gas pressure
applied to the unit exceed 2 psi. Leak test all
external piping thoroughly using a soap and
water solution or suitable equivalent. The gas
piping used must meet all applicable codes.
2.7.1 Gas Supply Specifications.
The gas supply input specifications to the unit
for Natural Gas are as follows:
The maximum static pressure to the unit must
not exceed 2 psi. The minimum operating gas
pressure for natural gas is 4 inches W.C. for
both FM and IRI gas trains when the unit is firing
at maximum input. The gas supply pressure to
the unit must be of suff icient capacity to provide
1500 cfh while maintain ing the gas press ure at 4
inches W.C. for FM or IRI gas trains.
WARNING
NEVER USE MATCHES, CANDLES,
FLAMES OR OTHER SOURCES OF
IGNITION TO CHECK FOR GAS
LEAKS
Many soaps used for gas pipe leak
testing are corrosive to metals. Therefore, piping must be rinsed thoroughly
with clean water after leak checks
have been completed.
All gas piping m ust be arranged so that it
does not interfere with removal of any
covers, inhibit service/maintenance, or
restrict access between the unit and
walls, or another unit.
A 1-1/2 inch gas inlet connection is located on
the rear of the unit as shown in Figure 2-3.
.
CAUTION
NOTE
2.7.2 Manual Gas Shutoff Valve
A manual shut-off valve must be installed in th e
gas supply line upstream of the Boiler as shown
in Figure 2-6. M aximum allowable gas pressure
to the Boiler is 2 psi
NATURAL
GAS
SUPPLY
1-½” MANUAL
GAS SHUTOFF
VALVE
DIRT
TRAP
Prior to installation, all pipes should be deburred and internally clear ed of any scale, m etal
chips or other foreign particles. Do Not install
any flexible connectors or unapproved gas
fittings. Piping must be s upported from the floor,
ceiling or walls onl y and must not be supported
by the unit.
2-4
Figure 2-6
Manual Gas Shut-Off Valve Location
INSTALLATION
2.7.3 IRI Gas Train Kit
The IRI gas train is an optional gas train
configuration which is r e qui red i n s ome areas for
code compliance or for insurance purposes.
The IRI gas train is factor y pre-piped and wired.
See Appendix F, Drawing AP- A-830 f or details.
2.8 AC ELECTRICAL POWER WIRING
The AERCO Benchmark 1.5 Electrical Power
Wiring Guide, GF-40 60, must be co nsulted prior
to connecting any AC power wiring to the unit.
External AC power connect ions are made to the
unit inside the Power Box on the front panel of
the unit. Remove the front door of the unit to
access the Power Box mounted directly above
the Control Box. Loosen the four Power Box
cover screws and remove cover to access the
AC terminal connections inside the Power Box
(Figure 2-7).
NOTE
All electrical conduit and hardware must
be installed so that it does not interfere
with the removal of any un it cover s, inh ibit
service/maintenance, or prevent access
between the unit and walls or another
unit.
2.8.1 Electrical Power Requirements
The AERCO Benchmark 1.5 Boiler accepts 120
VAC, single-phase, 60 Hz @ 20 A. The Power
Box contains a terminal block as shown in
Figure 2-8. In addition, a wiring diagr am showing
the required AC power connections is provided
on the front cover of the Power Box.
Each Benchmark 1.5 Boil er must be connected
to a dedicated electrical circuit. NO OTHER
DEVICES SHOULD BE ON THE SAME
ELECTRICAL CIRCUIT AS THE BENCHMARK
BOILER. A means for disconnecting AC power
from the unit (such as a ser vice switch) mus t be
installed near th e unit for normal operation and
maintenance. All electrical connections should
be made in accordance with the National
Electrical Code and/ or with any applicable local
codes.
For electrical power wiring diagrams, see the
AERCO Benchmark 1.5 Electrical Power W iring
Guide, (GF-4060).
Figure 2-7
AC Input Terminal Block Location
Figure 2-8
AC Terminal Block Configurations
2.9 MODES OF OPERATION AND FIELD
CONTROL WIRING
The Benchmark 1.5 B oiler is available in severa l
different modes of operation. W hile each unit is
factory configured and wired for its intended
mode, some additional field wiring may be
required to complete th e installation. This wir ing
is typically connected to the Input/Output (I/O)
Box located on the lower por tion of the unit fr ont
panel (Figure 2-9) behind the removable front
door.
2-5
INSTALLATION
To access the I/O Box terminal strips shown in
Figure 2-10, loosen the four cover screws and
remove the cover. All field wiring is installed
from the rear of the panel by routing the wires
through one of the four bushings provided.
Refer to the wiring diagram provided on the
cover of the I/O Box (Figur e 2-10) when making
all wiring connections.
In addition to the term inal strips s hown in Figure
2-9, the I/O Box also contains a pre-wired
temperature transmitter which receives inlet air
temperature sensor readings and transmits this
signal to the variable frequency drive (VFD)
contained in the Benchm ark 1.5 Boil er. T he VFD
utilizes this input signal to adjust the rotation
speed of the blower.
Brief descriptions of each mode of operation,
and their wiring requirements, are provided in
the following paragr aphs. Additional information
concerning field wiring is prov ided in paragr aphs
2.9.1 through 2.9.9. Refer to Chapter 5 for
detailed information on the available modes of
operation.
Figure 2-9.
Input/Output (I/O) Box Location
Figure 2-10. I/O Box Terminal Strip
2-6
INSTALLATION
2.9.1 Constant Setpoint Mode
The Constant Setpoi nt Mode is used when it is
desired to have a fixed setpoint that does not
deviate. No wiring connections, other than AC
electrical power connections, are required for
this mode. However, if desired, fault monitor ing
or enable/disable in terlock wiring c an be utilized
(see paragraphs 2.9.9.1 and 2.9.10).
2.9.2 Indoor/Outdoor Reset Mode
This mode of operation increases supply water
temperature as outdoor te mperatures decrease.
An outside air temperatur e sensor (AERCO Part
No. 122790) is requ ired. The sensor MUST BE
wired to the I/O Box wiring term inals (see Figure
2-10). Refer to paragraph 2.10.1 for additional
information on outside air temperature sensor
installation.
2.9.3 Boiler Management System Mode
When using an AERCO Boiler Management
System (BMS), the field wiring is connected
between the BMS Panel and each Boiler’s I/O
Box terminal strip (Figure 2-10). Twisted
shielded pair wire f rom 18 to 22 AWG must be
utilized for the connections. The BMS Mode can
utilize either pulse width modulation (PWM)
signaling, or RS485 Modbu s s ignaling. F or PWM
signaling, connections are made from the
AERCO Boiler Management System to the
B.M.S. (PWM) IN terminals on the I/O Box
terminal strip. For RS485 Modus signaling,
connections are made from the BMS to the
RS485 COMM term inals on the I/O Box ter minal
strip. Polarity m ust be maintain ed and the shie ld
must be connected only at the AERCO BMS.
The boiler end of the shi eld m ust be left f loating.
For additional instructions, refer to Chapter 5,
paragraph 5.6 in t his manual. Also, ref er to GF108M, BMS -Operations Guide.
2.9.4 Remote Setpoint and Direct Drive
Modes
The Benchmark 1.5 Boiler can accept several
types of signal formats from an Energy
Management System (EMS), Building
Automation System (BAS) or other source, to
control either the setpoint (Remote Setpoint
Mode) or firing rate (Direct Drive Mode) of the
Boiler. These formats are:
• 4 to 20 mA/1 to 5 VDC
• 0 to 20 mA/0 to 5 VDC
• PWM – (Pulse W idth Modulated signal. See
para. 2.10.4)
• Network (RS485 Modbus. See para. 2.10.7)
While it is possible to c ontrol a boiler or boilers
using one of the previously described m odes of
operation, it ma y not be the method best suited
for the application. Prior to selecting one of
these modes of operation, it is recommended
that you consult with your local AERCO
representative or the factory for the mode of
operation that will work best with your
application. For m ore information on wir ing the
4 to 20 mA / 1to 5VDC or the 0 to 20 m A / 0 to 5
VDC, see paragraph 2.9.3.
2.9.5 Combination Mode
With a Combination Mode unit, field wiring is
between the unit’s I/O Box wiring terminals, the
CCP (Combination Contr ol Panel), an d the BMS
(Boiler Management System). The wiring must
be accomplished using twisted-shielded pair
wire from 18 to 22 AWG. Polarity must be
maintained. For further instructions and wiring
diagrams, refer to the GF-108 Boiler
Management System Operations Guide and the
CCP-1 data sheet.
2.10 I/O BOX CONNECTIONS
The types of input and output signals and
devices to be connecte d to the I/O Box terminals
shown in Figure 2-10 are described in the
following paragraphs.
CAUTION
DO NOT make any connections to the
I/O Box terminals labeled “NOT
USED”. Attempting to do so may
cause equipment damage.
2.10.1 OUTDOOR SENSOR IN
An outdoor air temperature sensor (AERCO Part
No. 122790) will be required primarily for the
Indoor/Outdoor reset m ode of operation. It can
also be used with anoth er m ode if it is desired to
use the outdoor sensor enable/disable feature.
This feature allows the boiler to be enabled or
disabled based on the outdoor air temperature.
The factory default for the outdoor sensor is
DISABLED. To enable the sensor and/or select
an enable/disable o utdoor temperature, see the
Configuration menu in Chapter 3.
The outdoor sensor m ay be wired up t o 200 feet
from the boiler. It is connected to the
OUTDOOR SENSOR IN and SENSOR
COMMON terminals in the I/O Box (see Figures
2-9 and 2-10). Wire the sensor using a twisted
shielded pair wire fr om 18 to 22 AWG. There is
no polarity to observe when terminating these
wires. The shield is to be c onnected only to the
2-7
INSTALLATION
terminals labeled SHIELD in the I/O Box. The
sensor end of the shield must be left free and
ungrounded.
When mounting the sensor, it must be located
on the North side of the building where an
average outside air temperature is expected.
The sensor must be shield ed f r om dir ect sunli ght
as well as impingement by the elements. If a
shield is used, it must allow for free air
circulation.
2.10.2 AUX SENSOR IN
The AUX SENSOR IN terminals can b e used to
add an additional temperature sensor for
monitoring purposes. This input is always
enabled and is a view-only input that can be
seen in the Operating Menu. The sensor must
be wired to the AUX S ENSOR IN and SENSOR
COMMON terminals and must be similar to
AERCO BALCO wire se nsor Part No. 124 49. A
resistance chart for this sensor is provided in
Appendix C.
2.10.3 ANALOG IN
The ANALOG IN + and – terminals are used
when an external signal is used to drive the
firing rate (Direct Drive Mode) or change the
setpoint (Remote Setpoint Mode) of the Boiler.
Either a 4 to 20 mA /1 to 5 VDC or a 0 t o 20 mA
/ 0 to 5 VDC signal may be used to vary the
setpoint or firing rate. T he factory def ault setting
is for 4 to 20 mA / 1 to 5 VDC, howev er this m a y
be changed to 0 to 20 mA / 0 to 5 VDC usi ng the
Configuration Menu described in Chapter 3. If
voltage rather than current is selected as the
drive signal, a DIP switch must be set on the
CPU Board located inside the Control Box.
Contact the AERCO factory for information on
setting DIP switches.
All of the supplied signals must be floating
(ungrounded) signals . Connectio ns bet ween the
signal source and the Boiler’s I/O Box must be
made using twiste d shiel ded pa ir wire fr om 18 to
22 AWG, such as Belden 9841 (see Figure
2-10). Polarity mu st be maintained. The shi eld
must be connected only at the source end and
must be left floating (not connected) at the
Boiler’s I/O Box.
Regardless of whether volt age or curr ent is used
for the drive signal, the y are linearly mapped to
a 40°F to 240°F setpoint or a 0% to 100% f iring
rate. No scaling for these signals is provided
2.10.4 B.M.S. (PWM) IN
These terminals are used to connect the
AERCO Boiler Management System (BMS) to
the unit. The BMS utilizes a 12 millisecond,
ON/OFF duty cycle. This duty cycle is Pulse
Width Modulated (PW M) to control f iring rate. A
0% firing rate = a 5% ON pulse and a 100%
firing rate = a 95% ON pulse.
2.10.5 SHIELD
The SHIELD terminals are us ed to terminate any
shields used on sensor wires connected to the
unit. Only shields m ust be connected to these
terminals.
2.10.6 mA OUT
These terminals provide a 4 to 20 mA output to
the VFD to control the rotational speed of the
blower. This function is enabled in the
Configuration Menu (Chapter 3, Table 3.4).
2.10.7 RS-485 COMM
These terminals are used for RS-485 MODBUS
serial communication between the unit and an
external “Master” suc h as a Boiler Management
System (BMS), Energy Management System
(EMS), Building Automation System (BAS) or
other suitable device.
2.10.8 EXHAUST SWITCH IN
These terminals permit an external exhaust
switch to be connected to the exhaust manifold
of the boiler. The exhaust switch should be a
normally open t ype s witc h (such as AERCO Par t
No. 123463) that closes (trips) at 500°F.
2.10.9 INTERLOCKS
The unit offers two interlock circuits for
interfacing with Energy Management Systems
and auxiliary equipment such as pumps or
louvers. These interlock s are called the Rem ote
Interlock and Delayed Interlock (Figure 2-10).
The wiring terminals for these interlocks are
located inside the I/O Box on the unit front
panel. The I/O Box cover contains a wiring
diagram which s hows th e ter m inal str ip locat ions
for these interlocks (REMOTE INTL’K IN and
DELAYED INTL’K IN). Both interlocks,
described below, are fac tory wired in the closed
position.
NOTE
Both the Delayed Interlock and Remote
Interlock MUST be in the closed position
to allow the unit to fire.
2-8
INSTALLATION
2.10.9.1 REMOTE INTERLOCK IN
The remote interlock circuit is provided to
remotely start (enable) and stop (disable) the
Boiler, if desired. The circuit is labeled
REMOTE INTL’K IN and is loc ate d i nsid e th e I/O
Box on the front panel. The circuit is 24 VAC
and is factory pre-wired in the c losed (jum pered)
position.
2.10.9.2 DELAYED INTERLOCK IN
The delayed interlock is typically used in
conjunction with the aux iliary relay described in
paragraph 2.10. This interlock circuit is located
in the purge section of the start string. It can be
connected to the proving device (end switch,
flow switch etc.) of an auxiliary piece of
equipment started b y the Boiler’s a uxiliary rela y.
The delayed interlock must be closed for the
boiler to fire.
If the delayed interl ock is connec ted t o a pr oving
device that requir es tim e to clos e (mak e), a tim e
delay (Aux Start On Dly) that holds the start
sequence of the boiler lon g enoug h for a proving
switch to make can be progr amm ed. Should the
proving switch not prove within the programm ed
time frame, the boiler will shut down. The Aux
Start On Dly can be progr ammed from 0 to 120
seconds. This option is locate in the
Configuration Menu (Chapter 3, Table 3-4).
2.12 FLUE GAS VENT INSTALLATION
The minimum allowable vent diameter for a
single Benchmark 1.5 Boiler is 6 inches.
The AERCO Benchmark Venting and
Combustion Air Guide, GF-4050, must be
consulted before any flue gas vent or inlet air
venting is designed or installed. U/L listed,
positive pressure, watertight vent materials as
specified in AERCO’s GF-4050, must be used
for safety and code com pliance. S ince the u nit is
capable of dischar ging low temperature ex haust
gases, horizontal sections of the flue vent
system must be pitched back to the unit a
minimum of 1/4 inch per foot to avoid
condensate pooling and allow for proper
drainage.
The combined pressure drop of vent and
combustion air systems must not exceed 140
equivalent feet of 6 inc h ducting. Fittings as we ll
as pipe lengths must be calculate d as part of the
equivalent length.
For a natural draf t installation the draf t must not
exceed ±0.25 inch W .C. These factors must be
planned into the vent installation. If the
maximum allowabl e equivalent lengt hs of piping
are exceeded, the unit will not operate properly
or reliably.
2.10.10 FAULT RELAY
The fault relay is a single pole double throw
(SPDT) relay having a normally open and
normally closed set of relay contacts that are
rated for 5 amps at 12 0 VAC and 5 amps at 30
VDC. The relay energizes when any fault
condition occurs and remains energized until the
fault is cleared and the CLEAR button is
depressed. The fault relay connections are
shown in Figure 2-10.
2.11 AUXILIARY RELAY CONTACTS
Each Boiler is equipped with a single pole
double throw (SPDT) relay that is energized
when there is a demand for heat and deenergized after the dem and for heat is satisf ied.
The relay is prov ided for the control of auxiliary
equipment, such as pumps and louvers, or can
be used as a Boiler status indictor (firing or n ot
firing). Its contacts are r ated for 120 VAC @ 5
amps. Refer to Figure 2- 10 to locate the AUX
RELAY terminals for wiring connections.
2.13 COMBUSTION AIR
The AERCO Benchmark Venting and
Combustion Air Guide, GF-4050 MUST be
consulted before any flue or com bustion supply
air venting is designed or implemented.
Combustion air supp ly is a direct r equirem ent of
ANSI 223.1, NFPA-54, and local codes. These
codes should be consulted before a permanent
design is determined.
The combustion air must be free of chlorine,
halogenated hydrocarbons, or other chemicals
that can become ha zardous when used in gasfired equipment. Common sources of these
compounds are swimming pools, degreasing
compounds, plastic proc essing and refrigerants.
Whenever the env ironment c ontains thes e t ypes
of chemicals, combustion air must be supplied
from a clean area outdoors for the protection
and longevity of the equipment.
2-9
INSTALLATION
The AERCO Benchm ark 1.5 Boiler is UL listed
for 100% sealed combustion. It can also be
installed using room air, provided there is an
adequate supply. (See paragraph 2.13.3 for
more information conc erning sealed com bustion
air). If the sealed combustion air option is not
being used, an inlet screen will be attached at
the air inlet on the top of the unit
The more common methods of supplying
combustion air are outlined below. For more
information concerning combustion air, consult
the AERCO Benchmark Venting and
Combustion Air Guide, GF-4050.
2.13.1 Combustion Air From Outside the
Building
Air supplied from outside the building must be
provided through two perm anent openings. Each
opening must have a free area of not less than
one square inch for each 4000 BTU/H boiler
input. The free area must take into account
restrictions such as louvers and bird screens.
2.13.2 Combustion Air From Inside The
Building
When combustion air is provided f rom within the
building, it must be supplied through two
permanent openings in an interior wall. Each
opening must have a free area of not less than
one square inch per 1000 BTU/H of total boiler
input. The free area must take into ac count any
restrictions such as louvers.
2.13.3 Sealed Combustion
The AERCO Benchm ark 1.5 Boiler is UL listed
for 100%-sealed combustion. For sealed
combustion installations, the screen on the air
inlet duct of the unit m ust be removed. T he inlet
air ductwork must then be attached directly to
the unit’s air inlet.
In a sealed combustion air application, the
combustion air ducting pre ssure losses must be
taken into account when calculating the total
maximum allowable venting run. See the
AERCO Benchmark Venting and Combustion
Air Guide, GF-40 50. When using the bo iler in a
sealed combustion air configuration, each unit
must have a minimum 8 inch diameter
connection at the unit.
2-10
CONTROL PANEL OPERATING PROCEDURES
CHAPTER 3 CONTROL PANEL OPERATING PROCEDURES
3.1 INTRODUCTION
The information in this Chapter provides a guide
to the operation of the Benchmark 1.5 Boiler
using the Control Panel mounted on the front of
the unit. It is imperative that the initial startup of
this unit be performed by factory trained
personnel. Operation prior to initial startup by
factory trained personnel will void the equipment
warranty. In addition, the following WARNINGS
and CAUTIONS must be observed at all times.
CAUTION
All of the installation procedures in
Chapter 2 must be completed before
attempting to start the unit.
WARNING
ELECTRICAL VOLTAGES IN THIS
SYSTEM MAY INCLUDE 460, 208
AND 24 VOLTS AC. IT MUST BE
SERVICED ONLY BY FACTORY
CERTIFIED SERVICE TECHNICIANS
WARNING
DO NOT ATTEMPT TO DRY FIRE
THE BOILER. STARTING THE UNIT
WITHOUT A FULL WATER LEVEL
CAN SERIOUSLY DAMAGE THE
UNIT AND MAY RESULT IN INJURY
TO PERSONNEL OR PROPERTY
DAMAGE. THIS SITUATION WILL
VOID ANY WARRANTY.
3.2 CONTROL PANEL DESCRIPTIO N
The Benchmark 1.5 Control Panel shown in
Figure 3-1 contains all of the controls, indicators
and displays necessary to operate, adjust and
troubleshoot the Benchmark 1.5 Boiler. These
operating controls, indicators and displays are
listed and described in Table 3-1. Additional
information on these items are provided in the
individual operating procedures provided in this
Chapter.
Figure 3-1.
Control Panel Front View
3-1
CONTROL PANEL OPERATING PROCEDURES
Table 3-1 Operating Controls, Indicators and Displays
ITEM
NO.
CONTROL, INDICATOR
OR DISPLAY
1 LED Status Indicators Four Status LEDs indicate the current operating status as
follows:
COMM
MANUAL
REMOTE
DEMAND
OUTLET
2
TEMPERATURE
Display
3 VFD Display Vacuum Fluorescent Display (VFD) consists of 2 lines each
Lights when RS-232 communication is occurring
Lights when the unit is being controlled using the front panel
keypad.
Lights when the unit is being controlled by an external signal
from an Energy Management System
Lights when there is a demand for heat.
3–Digit, 7–Segment LED display continuously displays the
outlet water temperature. The °F or °C LED next to the
display lights to indicate whether the displayed temperature is
in degrees Fahrenheit or degrees Celsius.
capable of displaying up to 16 alphanumeric characters. The
information displayed includes:
Startup Messages
Fault Messages
Operating Status Messages
FUNCTION
Menu Selection
RS-232 Port
4
FAULT Indicator Red FAULT LED indicator lights when a boiler alarm
5
CLEAR Key Turns off the FAULT indicator and clears the alarm message
6
READY Indicator
7
ON/OFF Switch
8
LOW WATER LEVEL
9
TEST/RESET Switches
Port permits a Laptop Computer or External Modem to be
connected to the unit’s Control Panel.
condition occurs. An alarm message will appear in the VFD.
if the alarm is no longer valid. Lockout type alarms will be
latched and cannot be cleared by simply pressing this key.
Troubleshooting may be required to clear these types of
alarms.
Lights ON/OFF switch is set to ON and all Pre-Purge
conditions have been satisfied.
Enables and disables boiler operation.
Allows operator to test operation of the water level monitor.
Pressing TEST opens the water level probe circuit and
simulates a Low Water Level alarm.
Pressing RESET resets the water level monitor circuit.
Pressing the CLEAR key (item 6) resets the display.
3-2
CONTROL PANEL OPERATING PROCEDURES
Table 3-1 Operating Controls, Indicators and Displays – Continued
ITEM
NO.
10 MENU Keypad Consists of 6 keys which provide the following functions for
CONTROL, INDICATOR
OR DISPLAY
the Control Panel Menus:
MENU
BACK
▲ (UP) Arrow When in one of the main menu categories (Figure 3-2),
▼ (DOWN) Arrow When in one of the main menu categories (Figure 3-2),
CHANGE
Steps through the main menu categories shown in Figure 3-
2. The Menu categories wrap around in the order shown.
Allows you to go back to the previous menu level without
changing any information. Continuously pressing this key
will bring you back to the default status display in the VFD.
Also, this key allows you to go back to the top of a main
menu category.
pressing the ▲ arrow key will select the displayed menu
category. If the CHANGE key was pressed and the menu
item is flashing, pressing the ▲ arrow key will increment the
selected setting.
pressing this key will select the displayed menu category. If
the CHANGE key was pressed and the menu item is
flashing, pressing the ▼ arrow key will decrement the
selected setting.
Permits a setting to be changed (edited). When the
CHANGE key is pressed, the displayed menu item will begin
to flash. Pressing the ▲ or ▼ arrow key when the item is
flashing will increment or decrement the displayed setting.
FUNCTION
11
12
ENTER
AUTO/MAN Switch
FIRE RATE Bargraph
Saves the modified menu settings in memory. The display
will stop flashing.
This switch toggles the boiler between the Automatic and
Manual modes of operation. When in the Manual (MAN)
mode, the front panel controls are enabled and the
MANUAL status LED lights.
When in the Automatic (AUTO) mode, the MANUAL status
LED will be off and the front panel controls disabled.
20 segment red LED bargraph continuously shows the Fire
Rate in 5% increments from 0 to 100%
3-3
CONTROL PANEL OPERATING PROCEDURES
3.3 CONTROL PANEL MENUS
The Control Panel incorporates an extensive
menu structure which permits the operator to set
up, and configure the unit. The menu structure
consists of four major menu categories as
shown in Figure 3-2. Each of the menus shown,
contain options which permit operating
parameters to be viewed or changed. The
menus are protected by a password to prevent
unauthorized use.
Prior to entering the correct password, the
options contained in the Operating, Setup,
Configuration and Tuning Menu categories can
be viewed. However, with the exception of
Internal Setpoint Temperature (Configuration
Menu), none of the viewable menu options can
be changed.
Once the valid password (159) is entered, the
options listed in the Setup. Configuration and
Tuning Menus can be viewed and changed, if
desired.
3.3.1 Menu Processing Procedure
Accessing and initiating each menu and option
is accomplished using the Menu Keys shown in
Figure 3-1. Therefore, it is imperative that you
be thoroughly familiar with the following basic
steps before attempting to perform specific
menu procedures.
around after the first or last available option
is reached.
6. To change the value or setting of a
displayed menu option, press the CHANGE
key. The displayed option will begin to flash.
Press the ▲ or ▼ arrow key to scroll
through the available menu option choices
for the option to be changed. The menu
option choices do not wrap around.
7. To select and store a changed menu item,
press the ENTER key.
1. The Control Panel will normally be in the
Operating Menu and the VFD will display the
current unit status. Pressing the ▲ or ▼
arrow key will display the other available
data items in the Operating Menu.
2. Press the MENU key. The display will show
the Setup Menu, which is the next menu
category shown in Figure 3-2. This menu
contains the Password option which must be
entered if other menu options will be
changed.
3. Continue pressing the MENU key until the
desired menu is displayed.
4. With the desired menu displayed, press the
▲ or ▼ arrow key. The first option in the
selected menu will be displayed.
5. Continue to press the ▲ or ▼ arrow key
until the desired menu option is displayed.
Pressing the ▲ arrow key will display the
available menu options in the Top-Down
sequence. Pressing the ▼ arrow key will
display the options in the Bottom-Up
sequence. The menu options will wrap-
Figure 3-2. Menu Structure
NOTE
The following paragraphs provide brief
descriptions of the options contained in each
menu. Refer to Appendix A for detailed
descriptions of each menu option. Refer to
Appendix B for listings and descriptions of
displayed startup, status and error
messages.
3-4
CONTROL PANEL OPERATING PROCEDURES
3.4 OPERATING M ENU
The Operating Menu displays a number of key
operating parameters for the unit as listed in
Table 3-2. This menu is “Read-Only” and does
not allow personnel to change or adjust any
displayed items. Since this menu is “Read-Only”,
it can be viewed at any time without entering a
password. Pressing the ▲ arrow key to display
the menu items in the order listed (Top-Down).
Pressing the ▼ arrow key will display the menu
items in reverse order (Bottom-Up).
3.5 SETUP MENU
The Setup Menu (Table 3-3) permits the
operator to enter the unit password (159) which
is required to change the menu options. To
prevent unauthorized use, the password will
Table 3-2. Operating Menu
Available Choices or Limits
Menu Item Display Minimum Maximum Default
Status Message
time-out after 1 hour. Therefore, the correct
password must be reentered when required. In
addition to permitting password entries, the
Setup Menu is also used to enter date and time,
units of temperature measurements and entries
required for external communication and control
of the unit via the RS-232 port. A view-only
software version display is also provided to
indicate the current Control Box software
version.
NOTE
The Outdoor Temp display item shown with
an asterisk in Table 3-2 will not be displayed
unless the Outdoor Sensor function has
been enabled in the Configuration Menu
(Table 3-4).
Active Setpoint 40°F 240°F
Aux Temp 30°F 245°F
Outdoor Temp* -70°F 130°F
Fire Rate In 0% Max Fire Rate
Flame Strength 0% 100%
Run Cycles 0 999,999
Run Hours 0 999,999
Fault Log 0 9 0
Table 3-3. Setup Menu
Available Choices or Limits
Menu Item Display Minimum Maximum Default
Passsword 0 9999 0
Language English English
Time 12:00 am 11:59 pm
Date 01/01/00 12/31/99
Unit of Temp Fahrenheit or Celsius Fahrenheit
Comm Address 0 127 0
Baud Rate 2400, 4800, 9600, 19.2K 9600
Software Ver 0.00 Ver 9.99
3-5
CONTROL PANEL OPERATING PROCEDURES
3.6 CONFIGURATION MENU
The Configuration Menu shown in Table 3-4
permits adjustment of the Internal Setpoint
(Setpt) temperature regardless of whether the
valid password has been entered. Setpt is
required for operation in the Constant Setpoint
mode. The remaining options in this menu
require the valid password to be entered, prior to
changing existing entries. This menu contains a
number of other configuration settings which
may or may not be displayed, depending on the
current operating mode setting.
Table 3-4. Configuration Menu
Available Choices or Limits
Menu Item Display Minimum Maximum Default
Internal Setpt Lo Temp Limit Hi Temp Limit 130°F
Unit Type Boiler or Water Heater Boiler
Unit Size 0.5 MBTU, 1.0 MBTU
1.5 MBTU, 2.0 MBTU
2.5 MBTU, 3.0 MBTU
Boiler Mode Constant Setpoint,
Remote Setpoint,
Combination
Outdoor Reset
NOTE
The Configuration Menu settings shown in
Table 3-4 are Factory-Set in accordance
with the requirements specified for each
individual order. Therefore, under normal
operating conditions, no changes will be
required.
1.0 MBTU
Constant
Setpoint
Direct Drive
Remote Signal
(If Mode = Remote
Setpoint, Direct Drive
or Combination)
Bldg Ref Temp
(If Mode = Outdoor
Reset)
Reset Ratio
(If Mode = Outdoor
Reset)
Outdoor Sensor Enabled or Disabled Disabled
System Start Tmp
(If Outdoor Sensor =
Enabled)
Setpt Lo Limit 40°F Setpt Hi Limit 60°F
Setpt Hi Limit Setpt Lo Limit 220°F 200°F
Temp Hi Limit 40°F 240°F 210°F
Max Fire Rate 40% 100% 100%
Pump Delay Timer 0 min. 30 min. 0 min.
Aux Start On Dly 0 sec. 120 sec. 0 sec.
4 – 20 mA/1 – 5V
0 -20 mA/0 – 5V
PWM Input (BMS)
Network
40°F 230°F 70°F
0.1 9.9 1.2
30°F 100°F 60°F
4 – 20 mA,
1-5V
3-6
CONTROL PANEL OPERATING PROCEDURES
Table 3-4. Configuration Menu - Continued
Available Choices or Limits
Menu Item Display Minimum Maximum Default
Failsafe Mode Shutdown or Constant Setpt Shutdown
*mA Output
(See CAUTION)
Low Fire Timer 2 sec. 120 sec. 2 sec.
Setpt Limiting Enabled or Disabled Disabled
Setpt Limit Band 0°F 10°F 5°F
*CAUTION: DO NOT CHANGE mA Output Menu Item from its Default setting.
Setpoint, Outlet Temp,
Fire Rate Out, Off
*Fire Rate
Out
3.7 TUNING MENU
The Tuning Menu items in Table 3-5 are Factory set for each individual unit. Do not change these menu
entries unless specifically requested to do so by Factory-Trained personnel.
Table 3-5. Tuning Menu
Available Choices or Limits
Menu Item Display Minimum Maximum Default
Prop Band 1°F 120°F 70°F
Integral Gain 0.00 2.00 1.00
Derivative Time 0.0 min 2.00 min 0.00 min
Reset Defaults? Yes
No
Are You Sure?
No
3.8 START SEQUENCE
When the Control Box ON/OFF switch is set to
the ON position, it checks all pre-purge safety
switches to ensure they are closed. These
switches include:
• Safety Shut-Off Valve Proof of Closure
(POC) switch
• Low Water Level switch
• High Water Temperature switch
• High Gas Pressure switch
• Low Gas Pressure switch
• Blower Proof switch
If all of the above switches are closed, the
READY light above the ON/OFF switch will light
and the unit will be in the Standby mode.
When there is a demand for heat, the following
events will occur:
NOTE
If any of the Pre-Purge safety device
switches are open, the appropriate fault
message will be displayed. Also, the
appropriate fault messages will be displayed
throughout the start sequence, if the
required conditions are not observed.
1. The DEMAND LED status indicator will light.
2. The unit checks to ensure that the Proof of
Closure (POC) switch in the downstream
Safety Shut-Off Valve (SSOV) is closed.
See Figure 3-3 for SSOV locations.
3-7
CONTROL PANEL OPERATING PROCEDURES
STEPPER
Figure 3-3.
SSOV Locations
MOTOR
DIAL
(DETAIL “A”)
100
3. With all required safety device switches
closed, a purge cycle will be initiated and the
following events will occur:
(a) The Blower relay energizes and turns
on blower.
(b) The Air/Fuel Valve rotates to the full-
open purge position and closes purge
position switch. The dial on the Air/Fuel
Valve (Figure 3-4) will read 100 to
indicate that it is full-open (100%).
(c) The FIRE RATE bargraph will show
100%.
4. Next, the blower proof switch on the Air/Fuel
Valve (Figure 3-5) closes. The display will
show Purging and indicate the elapsed time
of the purge cycle in seconds. The normal
(default) time for the purge cycle is 7
seconds.
5. Upon completion of the purge cycle, the
Control Box initiates an ignition cycle and
the following events occur:
(a) The Air/Fuel Valve rotates to the low-
fire ignition position and closes the
ignition switch. The dial on the Air/Fuel
Valve (Figure 3-6) will read between 25
and 35 to indicate that the valve is in
the low-fire position.
(b) The igniter relay is activated and
provides ignition spark.
(c) The gas Safety Shut-Off Valve (SSOV)
is energized (opened) allowing gas to
flow into the Air/Fuel Valve.
DETAIL “A”
Figure 3-4.
Air/Fuel Valve In Purge Position
Figure 3-5.
Blower Proof Switch
6. Up to 7 seconds will be allowed for ignition
to be detected. The igniter relay will be
turned off one second after flame is
detected.
7. After 2 seconds of continuous flame, Flame
Proven will be displayed and the flame
strength will be indicated. After 5 seconds,
the current date and time will be displayed in
place of the flame strength.
3-8
CONTROL PANEL OPERATING PROCEDURES
8. With the unit firing properly, it will be
controlled by the temperature controller
circuitry. The boiler’s FIRE RATE will be
continuously displayed on the front panel
bargraph.
Once the demand for heat has been satisfied,
the Control Box will turn off the dual SSOV gas
valves. The blower relay will be deactivated and
the Air/Fuel Valve will be closed. Standby will
be displayed.
DIAL
(DETAIL “A”)
3.9 START/STOP LEVELS
The start and stop levels are the fire rate
percentages that start and stop the unit, based
on load. These levels are Factory preset as
follows:
Start Level: 20%
Stop Level: 16%
Normally, these settings should not require
adjustment.
Note that the energy input of the boiler is not
linearly related to the fire rate percentage
(Air/Fuel Valve position). Refer to Table 3-6 on
the following page for the relationship between
the energy input and fire rate percentage for a
unit running on natural gas.
STEPPER
MOTOR
5
2
DETAIL “A”
Figure 3-6.
Air/Fuel Valve In Ignition
3-9
CONTROL PANEL OPERATING PROCEDURES
Table 3-6.
Relationship Between Air/Fuel Valve Position and Energy Input For Unit Running On Natural Gas
Fire Rate,
Air/Fuel Valve
Position
(% Open)
0% 0 0
10% 0 0
16 %
(Stop Level)
20% 157,000 10%
30% 310,000 21%
40% 534,000 36%
50% 783,000 52%
60% 970,000 65%
70% 1,140,000 76%
80% 1,240,000 83%
90% 1,370,000 91%
100% 1,500,000 100%
Energy Input
(BTU/Hr)
75,000 5.0%
Boiler Energy Input
(% of Full Capacity)
3-10
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