Watts AERCO 58025-05 Owner's manual

TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
TECHNICAL INSTRUCTIONS
Latest Update: 10/16/2014
24-Month Maintenance
Kit P/N 58025-05
For BMK1.5LN Boilers
Description of Document:
This TID provides the procedures to perform
recommended 24-Month maintenance on the
following Benchmark Low NOx Boiler Models:
•Benchmark 1.5LN
•Benchmark 1.5LN Dual-Fuel
BMK 1.5LN Blower/Burner Assembly

VD2: 10/14/14 Page 2 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
TABLE OF CONTENTS
1. INTRODUCTION................................................................................3
2. CONTENTS OF 24-MONTH MAINTENANCE KIT ..............................3
3. TOOLS, TEST EQUIPMENT AND MATERIALS REQUIRED...............3
3.1 Tools ................................................................................................................3
3.2 Test Equipment...............................................................................................4
3.3 Materials ..........................................................................................................4
4. PRELIMINARY INSPECTION PROCEDURES ....................................4
5. WATERSIDE INSPECTION OF THE HEAT EXCHANGER..................5
6. FIRESIDE INSPECTIONS & COMPONENT REPLACEMENT .............7
6.1 Burner Maintenance ......................................................................................7
6.1.1 Burner Disassembly and Inspection........................................................................ 7
6.1.2 Preliminary Burner Reassembly........................................................................... 12
6.1.3 Burner Component Replacement.......................................................................... 13
6.1.4 Final Burner Reassembly...................................................................................... 15
6.2 Exhaust Manifold Maintenance....................................................................15
6.2.1 Exhaust Manifold Disassembly and Inspection.................................................... 15
6.2.2 Exhaust Manifold Reassembly ............................................................................. 16
6.2.3 Condensate Trap Component Replacement.......................................................... 17
6.3 Replacing the LWCO Probe/Capacitor Assembly......................................20
6.3.1 Low Water Cutoff (LWCO) Capacitor Integrity Test .......................................... 20
7. FINAL REASSEMBLY AND TESTING..............................................23
7.1 Set-Up and Reassembly After Maintenance...............................................23
7.2 Final Testing After Maintenance..................................................................23
Disclaimer
The information contained in this 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.
Technical Support:
(Mon–Fri, 8am-5pm EST)
1-800-526-0288
www.aerco.com

VD2: 10/14/14 Page 3 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
1. INTRODUCTION
This Technical Instruction Document (TID) provides the procedures to perform waterside and
fireside inspections of the heat exchanger contained in Benchmark 1.5LN and 1.5LN Dual-Fuel
boilers equipped with an Igniter-Injector.
This kit provides the parts required to perform the waterside and fireside inspections on the
Benchmark 1.5LN and Dual-Fuel Boilers.
2. CONTENTS OF 24-MONTH MAINTENANCE KIT
The items included in the 24-Month Maintenance Kit are listed in Table 1.
Table 1:Benchmark 1.5LN 24-Month Inspection Kit, Part No. 58025-05
ITEM
QTY
PART NO.
DESCRIPTION
1 1 58023
IGNITER/INJECTOR REPLACEMENT KIT:
1 x IGNITER-INJECTOR – P/N 66026
1 x NUT, COMPRESSION – P/N 56047
3 x WASHERS, CLOCKING (INDEXING) – P/N 53033
1 x LUBRICANT, ANTI-SEIZE - 89012
2 1 24356-1
FLAME DETECTOR REPLACEMENT KIT:
1 x FLAME DETECTOR – P/N 66034
1 x FLAME DETECTOR GASKET – P/N 81048
3 1 84020 EXHAUST MANIFOLD SEAL
4 2 81063 BURNER GASKETS
5 1 81064 BLOWER GASKET
6 1 84017 CONDENSATE TRAP O-RING
7 1 81092 CONDENSATE TRAP ORIFICE GASKET (.25" I.D.)
8 1 88003 AIR/FUEL VALVE TO GAS TRAIN O-RING
9 1 69126 LWCO / CAPACITOR ASSEMBLY KIT
10 1 81129 PLUG GASKET
3. TOOLS, TEST EQUIPMENT AND MATERIALS REQUIRED
The items required to perform the inspections, replacements and tests specified in these
instructions are listed in paragraph 3.1, 3.2 and 3.3 which follow.
3.1 Tools
Common hand tools, plus the items listed below are required:
•Small Wire Brush
•Flashlight
•Wrench set (box or open-ended)

VD2: 10/14/14 Page 4 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
3.2 Test Equipment
No test equipment is required to perform the 24-month inspections and maintenance included in
these instructions. However, following completion of these inspections, the Benchmark Boiler
should be tested using the combustion calibration procedures provided in O & M Manual
GF-120, GF-120M (Massachusetts only), or GF-121 (Dual-Fuel).
3.3 Materials
Expendable materials required to perform the procedures described in this bulletin are not
included in the 24 -Month Inspection Kits. These materials may include such items as:
•Pipe joint compound
•Teflon tape
•Cleaning solvents and materials
•Loctite 246
4. PRELIMINARY INSPECTION PROCEDURES
The detailed procedures required to perform the waterside and fireside inspections included in
these instructions are provided in sections 5 and 6. However, prior to performing the procedures
in section 5 and 6, perform the preliminary safety, set-up and disassembly procedures
described in the following steps:
WARNING!
FAILURE TO FOLLOW SAFETY INSTRUCTIONS REGARDING
PREPARATION OF THE UNIT, AS DESCRIBED BELOW, MAY
RESULT IN INJURY, DEATH, OR DAMAGE TO EQUIPMENT.
Preliminary Inspection Instructions
1. At the front panel of the unit, set the ON/OFF switch on the C-More Control Panel to the
OFF position.
2. Disconnect electrical power to the unit by turning off the external circuit breaker.
3. Turn off the external gas supply shutoff valve.
4. Close the water supply and return valves to the unit.
5. Refer to Figure 1 and remove the top and side panels of the unit.
6. With the top and side panels removed, the Benchmark 3.0LN Burner, heat exchanger and
Exhaust Manifold can be accessed to prepare the boiler for the required waterside and
fireside inspections described in sections 5 and 6.

VD2: 10/14/14 Page 5 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 1: Benchmark 1.5 Low NOx (LN) Boiler
5. WATERSIDE INSPECTION OF THE HEAT EXCHANGER
Benchmark 1.5LN Models contain a single heat exchanger, as shown in Figure 2. Perform the
waterside inspection as follows:
Burner Preliminary Disassembly and Inspection Instructions
1. Ensure that the preliminary safety, set-up, and disassembly procedures in section 4 have
been performed to provide access to the heat exchanger of the unit.
2. Allow the unit to cool prior to proceeding.
3. At the rear of the unit (Figure 3), slowly open the drain valve and drain the boiler water
from the heat exchanger.
4. Open the P&T relief valve (Figure 2) to allow air to enter the heat exchanger during
draining.
5. After the heat exchanger has been drained, remove the 2-1/2 inch access port plug on the
right side of the heat exchanger, as shown in Figure 2.
6. If waterside inspection is required by your local inspector, follow the inspector's
instructions. Upon satisfactory completion of the inspection, proceed to step 7.
7. Apply pipe compound to the threads of the access port plugs and replace them using a
pipe wrench.
8. Close the drain valve at the rear of the boiler.
9. Close the P&T relief valve.
10. Open the water supply and return valves to the unit and refill the heat exchanger. This
completes the waterside inspection for the unit.
2 SIDE PANELS
(EACH SIDE)
TOP PANEL

VD2: 10/14/14 Page 6 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 2: Benchmark 1.5LN - (Side View)
Figure 3:Benchmark 1.5LN - (Rear View)

VD2: 10/14/14 Page 7 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
6. FIRESIDE INSPECTIONS & COMPONENT REPLACEMENT
The heat exchanger fireside inspection includes removal of the Burner and recommended
replacement of Burner components and inspection of the Exhaust Manifold assembly and
replacement of Condensate Trap components. The 24-Month Maintenance Kit includes the
recommended replacement parts for annual maintenance which should also be performed at
this time. Therefore, the procedures in this section are organized as follows:
Burner Maintenance – section 6.1:
•Burner Disassembly and Inspection
•Preliminary Burner Reassembly
•Burner Component Replacement
•Final Burner Reassembly
Exhaust Manifold & Condensate Maintenance – section 6.2:
•Exhaust Manifold Disassembly and Inspection
•Exhaust Manifold Reassembly
•Condensate Trap Component Replacement
LWCO (Low Water Cut-Off) Capacitor Replacement and Testing – section 6.3:
•LWCO replacement
•LWCO testing
6.1 Burner Maintenance
Perform the fireside inspections of the low NOx Burner and replacement of Burner component
parts using the procedures in the following paragraphs, 6.1.1 and 6.1.2.
6.1.1 Burner Disassembly and Inspection
The Burner Assembly is located at the top of the heat exchanger as shown in Figure 4. The
complete Burner Assembly for Benchmark 1.5LN also includes the Blower and Air/Fuel Valve
assemblies for the unit. Figure 4 shows the Burner Assembly mounting details and Figure 5
shows an exploded diagram of the complete Burner Assembly removed from the unit.

VD2: 10/14/14 Page 8 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 4: Benchmark 1.5LN - Top View
FLAME
DETECTOR
(P/N 66034)
IGNITER-
INJECTOR
(P/N 66026)

VD2: 10/14/14 Page 9 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 5: BMK1.5LN Burner Assembly - Exploded View
Remove and inspect the Burner Assembly as follows:
Burner Preliminary Disassembly and Inspection Instructions
1. Ensure that the preliminary set-up and disassembly procedures in section 4 have been
completed.
WARNING
THE BURNER ASSEMBLY MAY BE EXTREMELY HOT. TO
AVOID BURNS, ALLOW IT TO COOL SUFFICIENTLY BEFORE
ATTEMPTING TO REMOVE IT FOR INSPECTION.
2. Disconnect the lead wire from the Flame Detector shown in Figure 6. Unscrew the two
screws and remove the Flame Detector and gasket.
3. Disconnect the igniter cable from the igniter (Figure 6).
BURNER GASKET (P/N 81063)
BLOWER GASKET
(P/N 81064)
IGNITER-INJECTOR
(P/N 66026)
FLAME DETECTOR GASKET (P/N 81048)
FLAME DETECTOR (P/N 66034)
OBSERVATION PORT
GROUNDING SCREW
BURNER
BURNER FLANGE
BURNER PLATE
HEX HEAD SCREWS (4)
A/F VALVE TO GAS TRAIN
O-RING (P/N 88003)
AIR/FUEL
VALVE
BLOCKED INLET SWITCH
BLOWER PROOF SWITCH
BLOWER
STAGED IGNITION SOLENOID
BURNER GASKET (P/N 81063)

VD2: 10/14/14 Page 10 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
4. Refer to the partial exploded view in Figure 6. Using a 7/16” open-end wrench, disconnect
the compression nut securing the Gas Injector Tube of the Igniter-Injector to the elbow of
the Staged Ignition Assembly. Remove the compression nut from the elbow and discard,
as it will be replaced with a new one from the kit at reassembly. Disconnect the Staged
Ignition Assembly from the Igniter-Injector.
5. Next, loosen and remove the Igniter-Injector from the Burner Plate using a 1" open-end
wrench.
6. Remove the two screws securing the Plug Gasket (P/N 81129), remove the existing Plug
Gasket and replace it with one from the kit, and then secure it with the two screws.
7. Disconnect the unit wiring harness connectors from the Air/Fuel Valve and Blower motor
(Figure 5).
8. Disconnect the Fast-On wire leads connected to the Blower Proof Switch and Blocked Inlet
Switch (Figure 5).
Figure 6: Partial Exploded View Showing Flame Detector, Igniter-Injector, and
Staged Ignition Assembly on Burner Plate
9. Disconnect the Gas-Train from the Air/Fuel Valve flange by removing the four (4) 1/2" bolts
and nuts (Figure 4). Remove the Air/Fuel Valve to Gas Train O-ring (P/N 88003), as it will
be replaced at reassembly.
10. Disconnect the inlet air flex hose from the Air/Fuel Valve (Figures 2 & 4) by loosening the
hose clamp.
COMPRESSION NUT
(P/N 56047)
IGNITER-INJECTOR
(P/N 66026)
IGNITER-INJECTOR
CABLE ATTACHED HERE
INDEXING WASHERS
(QTY=3) AS REQ’D
(P/N 53033)
BURNER PLATE
FLAME DETECTOR
GASKET (P/N 81048)
FLAME DETECTOR
(P/N 66034)
FLAME DETECTOR
LEAD WIRE
ATTACHED HERE
STAGED IGNITION
SOLENOID
INJECTOR TUBE
PLUG GASKET
(P/N 81129)

VD2: 10/14/14 Page 11 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
IMPORTANT!
There are some installations where it may be necessary to
disassemble the Air/Fuel valve from the Blower to access the
Burner. Note that there is a gasket located between the A/F Valve
and Blower adapter (P/N 81057), as shown in Figure 7. If you
disassemble the Blower from the A/V Valve, check this gasket for
damage and wear and retain for later reassembly. If replacement
is necessary, contact AERCO technical support for assistance.
11. If it is necessary to separate the Blower from the A/F Valve, refer to Figure 7, and remove
the 6 bolts from A/F Valve as shown. Retain the gasket (P/N 81057) for later reassembly.
Figure 7: Exploded Veiw of Blower & Air/Fuel Valve (BMK1.5LN)
12. Remove the four (4) 1/4-20 hex nuts and flat washers securing the Blower to the Burner
Plate (Figure 5).
13. If the A/F Valve and Blower are NOT separated (see step 11), remove the Blower and
Air/Fuel Valve from the Burner Plate as one piece, lifting it straight up. If separated,
remove both assemblies as is most convenient for your installation.
14. Remove the Blower Gasket that lies between the Blower and Burner Plate (Figure 5). This
will be replaced at reassembly with a new Blower Gasket (P/N 81064) provided in the kit.
15. Remove the grounding screw on the Burner Plate (Figures 4 and 5).
16. Remove the eight (8) 3/8-16 nuts from the Burner flange (Figure 4) using a 9/16” wrench.
Blower & A/F Valve
Adapter Gasket
(P/N 81057)
Remove six bolts
to separate A/F
Valve from
Blower
Blower
Air/Fuel
Valve
Gas train was
disassembled
from here in
Step 9
.

VD2: 10/14/14 Page 12 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
NOTE
The Burner Plate is heavy, weighing approximately 20 pounds.
14. Remove the Burner Plate and then the Burner by pulling straight up. Do not scrape or bang
the Burner Mesh during removal of the Burner.
15. Inspect the removed Burner for damage, warping or discoloration. If the Burner is
damaged, especially in the Observation Port or Staged Ignition Assembly area of the
flange, it must be replaced with a new assembly. Inspect the Burner Mesh with a flashlight
inside for evidence of clogging or sagging.
16. Inspect lower Burner Gasket for leak paths, gouges, or damage. An undamaged lower
gasket may be left in place without causing any adverse issues.
IMPORTANT!
Follow appropriate local and state regulations as pertains to
inspection of critical boiler parts.
During inspection, if the Burner and/or mesh appear damaged,
contact AERCO technical support for information regarding Burner
replacement. If undamaged, proceed to section 6.1.2.
6.1.2 Preliminary Burner Reassembly
Before Burner components may be replaced, the Burner must be partially reassembled as
follows:
Preliminary Burner Reassembly Instructions
1. Remove the two old Burner Gaskets (P/N 81063) and install the new gaskets from the kit.
Ensure that the gaskets and Burner are aligned with the Igniter-Injector and Flame
Detector slots in the heat exchanger top head.
IMPORTANT!
When installing new Burner Gaskets, it is imperative that the
gaskets be properly aligned to assure that the cutouts for the
Observation Port, Igniter-Injector, and Flame Detector line up with
those in the heat exchanger top plate, Burner flange and Burner
housing. Failure to properly align these items may result in
damage to the gaskets or interference with the components.
2. Reassemble the Air/Fuel Valve to the Blower (if needed) per figure 7. Ensure that the
Blower Gasket removed previously is included. Tighten each bolt in an alternating pattern
to ensure a uniform seal between the Blower and the A/F Valve.
3. Place a new Blower Gasket (P/N 81064) from the kit, aligning it with the Blower mounting
holes on the Burner Plate.
4. Next, place the Blower-A/F Valve assembly onto the gasket and Burner Plate. Insert the
six 1/4-20 bolts into the tapped holes on the Blower and thread each 1/4-20 bolt one or two
revolutions to aid in proper alignment. Tighten each bolt in an alternating pattern to ensure
a uniform seal around the Blower base.

VD2: 10/14/14 Page 13 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
5. To each of the eight (8) Burner mounting studs coming up through the Burner flange, add
one of the 3/8” flat washers removed during disassembly.
6. After placing the washers, apply Loctite 246 to the Burner mounting studs. While
supporting the housing so it is level with the Burner flange, use a torque wrench to tighten
the eight (8) 3/8-16 hex nuts on the Burner flange to 35 ± 5 ft-lbs. Use an alternating
pattern when tightening the hex nuts to ensure a uniform seal.
7. Replace the Air/Fuel Valve to Gas Train O-ring (P/N 88003) with one in the kit and then
reassemble the Air/Fuel Valve to the gas-train flange by reinstalling the four (4) 1/2" bolts
and nuts (Figure 4). Use an alternating pattern when tightening the bolts to ensure a
uniform seal. NOTE
At this point in the Burner reassembly process, the following new
items should be installed (included in the maintenance kit). See
section 6.1.2 for component replacement instructions.
•Blower Gasket (P/N 81064)
•Burner Gaskets (2 x P/N 81063)
•Air/Fuel Valve to Gas-Train O-Ring (P/N 88003)
•Igniter-Injector (P/N 66026, a component of kit P/N 58023).
•Flame Detector and gasket (P/N 66034 & 81048).
8. Replace Burner and Burner Plate back onto heat exchanger, making sure to align the
holes for the Igniter-Injector, Flame Detector, and other components in the Burner Plate
with the holes of the heat exchanger top head.
9. Proceed to section 6.1.2 for instructions to replace the Igniter-Injector and Flame Detector
components prior to final Burner reassembly.
6.1.3 Burner Component Replacement
The old components that need to be replaced have already been removed during the
disassembly process in section 6.1.1. The following instructions show how to install the new
parts during the Burner reassembly process.
6.1.3.1 Igniter-Injector Installation
The spark Igniter-Injector (P/N 66026) installation is accomplished as follows:
Igniter-Injector Installation Instructions
1. Burner, Burner Plate, and Blower must first be completely reassembled to the Burner.
2. Prior to installing the replacement Igniter-Injector, high temperature, conductive, anti-seize
lubricant must be applied to the Igniter-Injector threads. A small tube of this lubricant is
included in the Igniter-Injector replacement kit (P/N 58023).

VD2: 10/14/14 Page 14 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
NOTE
The Igniter-Injector hardware contains a compression nut (P/N
56047) with a built-in ferrule and three clocking (indexing) washers
(P/N 53033). These washers are used, as needed, to properly
position the Igniter-Injector’s gas injector tube, as described in the
following step.
3. Reinstall the Igniter-Injector and, if necessary, install 1, 2 or 3 clocking washers to
properly position the Gas Injector Tube within the 120° angle shown in Figure 8. Torque
the Igniter-Injector to 15 ft-lbs. Do not over tighten.
Figure 8: Benchmark 1.5LN Igniter-Injector Orientation
4. Connect the Staged Ignition Assembly to the Igniter-Injector’s Gas Tube by securing the
compression nut (P/N 56047) to the elbow of the Staged Ignition Assembly using a 7/16”
open-ended wrench. Position the Staged Ignition Solenoid so it is not contacting any other
components of the Burner Assembly or heat exchanger.
5. Reconnect the Igniter-Injector cable. This completes the replacement of the Igniter-Injector.
6.1.3.2 Flame Detector Installation
Flame Detector (P/N 66034) and gasket (P/N 81047) installation is accomplished as follows:
Flame Detector Installation Instructions
1. Refer to Figures 5 and 6 to locate the Flame Detector installation location.
2. Install the replacement Flame Detector (P/N 66034) and Flame Detector Gasket (P/N
81047) in the location shown. Secure the Flame Detector to the Burner housing flange
using the two screws removed previously.

VD2: 10/14/14 Page 15 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
6.1.4 Final Burner Reassembly
After Burner component replacement (Section 6.1.3), continue Burner reassembly as follows:
Final Burner Reassembly Instructions
1. Reinstall the grounding screw to the Burner Plate (Figure 4).
2. Connect lead wire to the Flame Detector (Figure 6).
3. Attach igniter cable to the Igniter-Injector assembly (Figure 6).
4. Reconnect the unit wiring harness connectors to the Air/Fuel Valve and Blower motor.
5. Reconnect the wire leads connected to the Blower proof switch and blocked inlet switch.
6. During the Burner maintenance process, the following items (included in the maintenance
kit) should have been replaced:
•Blower Gasket (P/N 81064).
•Burner Gaskets (2 x P/N 81063)
•Air/Fuel Valve to Gas-Train O-Ring (P/N 88003)
•Igniter-Injector (P/N 66026, a component of kit P/N 58023).
•Flame Detector and gasket (P/N 66034 & 81048)
7. This completes the Burner Maintenance for the BMK1.5LN boiler. Proceed to section 6.2
for Exhaust Manifold maintenance instructions.
6.2 Exhaust Manifold Maintenance
The Exhaust Manifold of the Benchmark 1.5LN is installed at the rear of the unit as shown in
Figure 9.
6.2.1 Exhaust Manifold Disassembly and Inspection
To remove and inspect the Exhaust Manifold:
Exhaust Manifold Disassembly and Inspection Instructions
1. Remove the four (4) bolts securing the flue starter section collar to the top of the exhaust
manifold.
2. Disconnect the flue starter section from the exhaust manifold.
3. Disconnect the Condensate Trap drain hose from the 1-1/2" O.D. pipe on the exhaust
manifold.
4. Using a 3/4" socket wrench, remove the three bolts securing the exhaust manifold to the
heat exchanger (Figure 9).
5. Remove the exhaust manifold and seal from the rear of the unit.
6. Remove the silicone rubber seal from the recess in the flange of the exhaust manifold.
Ensure that all seal residue is removed from the flanges of the exhaust manifold and heat
exchanger.
7. Inspect and clean the exhaust manifold as necessary.

VD2: 10/14/14 Page 16 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 9: Benchmark 1.5LN Exhaust Manifold Location – Right Side View
6.2.2 Exhaust Manifold Reassembly
To reassemble the Exhaust Manifold:
Exhaust Manifold Reassembly Instructions
1. Refer to Figure 10 and replace the exhaust manifold seal (part no. 84020) with the new
seal provided in the 24-month maintenance kit. Install the adhesive-backed seal in the
recess of the exhaust manifold flange (adhesive side down).
2. Align the exhaust manifold with the lower heat exchanger flange and secure it in place
using the three (3) bolts removed in step 4 of disassembly instructions. Alternately tighten
the bolts to obtain a uniform seal.
3. Reconnect the flue starter section to the exhaust manifold.
4. Prior to reconnecting the Condensate Trap, perform the procedures described in
paragraph 6.2.3.
5. Upon completion of the procedures in paragraph 6.2.2, reconnect the Condensate Trap to
the 1-1/2" O.D. pipe on the exhaust manifold per Figure 12.

VD2: 10/14/14 Page 17 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 10:Benchmark 1.5LN Exhaust Manifold
6.2.3 Condensate Trap Component Replacement
For Benchmark 2.0 boilers, the Condensate Trap (P/N 24060) is attached to the connecting
manifold drain pipe using a special adapter (Figure 11).
NOTE
The Condensate Trap should already be disconnected from the
Exhaust Manifold of the unit during the Exhaust Manifold
inspection procedure in section 6.2.1.
NOTE
There are two slightly different types of Condensate Traps that
may be used in your configuration; an older style with a separate
inlet adapter, and a newer style with a built-in adapter (see Figure
10). Maintenance is the same, except that the newer style does
not need an orifice gasket (Step 5).

VD2: 10/14/14 Page 18 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
This trap should be disconnected from the connecting manifold and serviced as follows:
Condensate Trap Component Replacement Instructions
1. Remove the connections on the inlet and outlet sides of the Condensate Trap shown in
Figure 12.
2. Refer to Figure 11 and loosen the four (4) thumbscrews securing the cover on the
Condensate Trap. Remove the cover.
3. Remove and discard the O-ring gasket currently installed in trap. It will be replaced with the
new O-ring included in the Maintenance Kit during reassembly.
4. Remove the float (with float guide attached) from the Condensate Trap.
5. For Old Style Condensate Trap (see Figure 11),remove, discard, and replace the
currently installed orifice gasket from the trap with the one provided in the kit. New Style
Trap does NOT use an orifice gasket, so this step is not necessary for that type.
6. Thoroughly clean the trap and float. Also inspect the drain piping for blockage. If the trap
cannot be thoroughly cleaned, replace the Condensate Trap.
7. Check the condensate drain port on the Exhaust Manifold (Figure 12) to ensure it is clear
of blockage.
8. After the above items have been inspected and thoroughly cleaned, replace the orifice
gasket (use new gasket) and float in the Condensate Trap. Replace the O-ring (use new
O-ring) and replace the trap cover.
9. Reassemble all piping and hose connections to the Condensate Trap inlet and outlet.
Reconnect trap to condensate drain connection on the connecting manifold.

VD2: 10/14/14 Page 19 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
Figure 11: Condensate Trap P/N 24060 (Old and New Styles)
Figure 12: Exhaust Manifold Condensate Drain Location. Old (left) and New
(right) Style Trap - BMK1.5LN Partial Left Side View

VD2: 10/14/14 Page 20 of 24
BMK1.5 LN Boiler 24-Month Maintenance Kit #58025-05 Instructions
Technical Instruction Document
TID-0066_0B
AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 •Phone: [phone]
6.3 Replacing the LWCO Probe/Capacitor Assembly
The replacement LWCO probe sensor comes with a capacitor assembly attached. This
procedure replaces an old probe assembly with a new probe assembly (P/N 69126).
Replacing the LWCO Probe/Capacitor Assembly
1. Cut the shell harness wire just below the female spade connector (Figure 13). The new
LWCO assembly includes a new female connector to crimp onto the shell harness wire.
Figure 13: Removing Old LWCO Probe/Capacitor Assembly
2. Remove the LWCO probe from the recess well on the hot water outlet piping by unscrewing
the brass coupling to which it is attached.
3. Retrieve the new LWCO probe from the kit and sparingly apply an NSF approved pipe dope
to the threads of the brass coupling (Do NOT use Teflon tape) and install into the probe well
vacated by the old LWCO probe.
4. The new LWCO assembly comes with a spare female connector already inserted into the
male connector, and this should be crimped onto the stripped end of the shell harness wire.
6.3.1 Low Water Cutoff (LWCO) Capacitor Integrity Test
The LWCO capacitor should be tested for electrical shorts after it has been replaced. The
LWCO Capacitor test consists of two parts as described in the next two sections. The first
procedure explains how to test for electrical shorting of the LWCO probe capacitor, while
the second procedure instructs how to perform the standard Low Water Cutoff test using
the C-More controls.
MALE SPADE
CONNECTOR
FEMALE SPADE
CONN.ON THE
SHELL HARNESS WIRE
OLD LWCO PROBE
CUT OFF WIRE
TO OLD LWCO
ASSEMBLY
HERE
OLD CAPACITOR
(COVERED BY LARGE
SHRINK TUBING)
PROBE WELL OF
HOT WATER
OUTLET PIPING
LWCO PROBE
& CAPACITOR
ASSEMBLY