Instructions / Assembly
Table Of Contents
- Part 1 - General Safety Information
 - Part 2 - Before You Start
 - Part 3 - Prepare the Boiler
- A. Locating the Boiler
 - B. Structure
 - C. Leveling
 - D. Clearances for Service Access
 - E. Wall Mounting Considerations
 - F. Wall Mounting Instructions
 - G. Residential Garage and Closet Installations
 - H. Exhaust Vent and Intake Pipe
 - I. Carbon Monoxide Detectors
 - J. Prevent Combustion Air Contamination
 - K. Removing a Boiler from a Common Vent System
 - K. Water Chemistry Requirements*
 - L. Technical Specifications
 
 - Part 4 - Piping
- A. General Plumbing Information
 - B. Relief Valve
 - C. Backflow Preventer
 - D. Potable Expansion Tank
 - E. Circulators
 - F. Hydronic Piping with Circulators, Zone Valves, and Multiple Boilers
 - G. Circulator Sizing
 - H. Check / Control Water Chemistry
 - I. Plumbing
 - J. Fill and Purge Heating System
 - K. Glycol Antifreeze Solutions
 - L. Zoning with Zone Valves
 - M. Zoning with Circulators
 - N. Multiple Boilers
 - O. Applications*
 
 - Part 5 - Venting
 - Part 6 - Condensate Removal
 - Part 7 - Wiring
- A. Installation Must Comply With
 - B. Field Wiring Terminations
 - C. Field Wiring
 - D. Line Voltage Wiring for Standard Boiler
 - E. Alarm Connections
 - F. Low Voltage Connections for Standard Boiler
 - G. Thermostat
 - H. Outdoor Sensor
 - I. Indirect Sensor
 - J. Optional 0-10 Volt Building Control Signal
 - K. Optional UL353 Low Water Cut-Off Interface Kit
 - L. Wiring of Cascade System Communication Bus
 - M. Cascade Master Pump and Sensor Wiring
 - N. Cascade Follower Pump and Sensor Wiring
 
 - Part 8 - Gas Connections
 - Part 9 - Start-Up Preparation
- A. Check / Control Water Chemistry
 - B. Check for Gas Leaks
 - C. Freeze Protection (When Used)
 - D. Fill and Test Water System
 - E. Purge Air from Water System
 - F. Check Thermostat Circuit(s)
 - G. Condensate Removal
 - H. Final Checks Before Starting Boiler
 - I. Setting Up a Single Boiler
 - J. Setting Up a Cascaded System
 - K. Lockout Condition
 - L. Cascade System Programming
 
 - Part 10 - Start-Up Procedure
 - Part 11 - Start-Up Procedures for the Installer
 - Part 12 - Troubleshooting
 - Part 13 - Maintenance
 - Part 14 - Shutdown
 - Part 15 - Installation Checklist
 - Part 16 - Maintenance Report
 - Part 17 - Replacement Parts
 

LP-387 Rev. 011 Rel. 006 Date 6.28.19
19
NOTE: Boiler failure due to improper water chemistry is not 
covered by warranty.
•  Water pH between 6.5 and 8.5
•  Hardness less than 7 grains (120 mg/L) (Water temperatures 
of 140
o
F and greater)
•  Chloride concentration less than 100 ppm (mg/L)
•  Total Dissolved Solids (TDS) less than 500 ppm (mg/L)
*NOTE: It is recommended to clean the heat exchanger at least once a 
year to prevent lime scale buildup. To clean the heat exchanger, follow 
the maintenance procedure in this manual.
Clean system to remove sediment*
1. You must thoroughly ush the system (without boiler connected) 
to remove sediment. The high-eciency heat exchanger can be 
damaged by buildup or corrosion due to sediment. 
2. For zoned systems, ush each zone separately through a purge 
valve. (If purge valves and isolation valves are not already installed, 
install them to properly clean the system.) 
3. Flush system until water runs clean and you are sure piping is free 
of sediment.
Test/replace freeze protection uid 
1. For systems using freeze protection uids, follow uid manufacturer’s 
instructions to verify inhibitor level and that other uid characteristics 
are satisfactory. 
2. Freeze protection uid must be replaced periodically due to 
degradation of inhibitors over time. Follow all uid manufacturer 
instructions.
Piping Components
Heating System Piping
System piping MUST be sized per technical pipe requirements listed 
in Tables 7 and 8. Reducing pipe size can restrict ow rate through the 
boiler, causing inadvertent short cycling and poor system performance.
H. Check / Control Water Chemistry
Model Minimum Pipe Sizes
55 / 80 / 110 1” NPT
155 / 199 / 285 1 1/4” NPT
399 1 1/2” NPT
Table 8 - Minimum Pipe Sizes
I. Plumbing
NOTE: Observe the minimum 1” clearance around all uninsulated hot 
water pipes when openings around pipes are not protected by non-
combustible materials.
Basic steps are listed below, with illustration that will guide you 
This boiler should not be operated as a potable hot water heater. It 
should not be used as a direct hot water heating device.
J. Fill and Purge Heating System
1. Attach the hose to balance and purge hose connector or drain 
valve and run hose to nearest drain.
2. Close the other side of the balance and purge valve or shut o 
valve after the drain.
3. Open the rst zone balance and purge or drain valve to let water 
ow out of the hose. If zone valves are used, open the valves one at 
a time manually. NOTE: You should check zone valve manufacturer’s 
instructions prior to opening valves manually, so as not to damage 
the zone valve.
4. Manually operate ll valve regulator. When water runs out of 
the hose, you will see a steady stream without bubbles. Close the 
balance and purge valve or drain to stop the water from owing. 
Disconnect the hose and connect it to next zone to be purged.
5. Repeat this procedure for additional zones (one at a time).
For installations that incorporate standing iron radiation and 
systems with manual vents at the high points, follow the previous 
section and, starting with the nearest manual air vent, open 
the vent until water ows out. Then close the vent. Repeat the 
procedure, working your way toward the furthest air vent. It may 
be necessary to install a basket strainer in an older system where 
larger amounts of sediment may be present. Annual cleaning of 
the strainer may be necessary.
Upon completion, make sure that the ll valve and zone valves are 
in automatic positions. You must also assure the purge and shut o 
valves are in open positions.
K. Glycol Antifreeze Solutions
Use only inhibited propylene glycol solutions which are specially 
formulated for hydronic systems. Ethylene glycol is toxic and can 
attack gaskets and seals used in hydronic systems. Glycol mixtures 
should not exceed 50%. Failure to do so could result in property 
damage, severe personal injury, or death due to scalds.
Check Valves
Field supplied. Check valves are recommended for installation as 
shown in Applications.
Isolation Valves
Field supplied. Full port ball valves are required. Failure to use full port 
ball valves could result in a restricted ow rate through the boiler.
Anti-Scald Mixing Valve
Field supplied. An anti-scald mixing valve is recommended when 
storing domestic hot water above 115°F.
Unions
Field supplied. Recommended for unit serviceability. DO NOT USE 
DIELECTRIC UNIONS! ONLY BRASS, COPPER, OR STAINLESS STEEL. 
Pressure Relief Valve
Factory supplied on boiler. The pressure relief valve is sized to ASME 
specications. Storage tank may require additional relief valves 
depending on local codes.
through the installation of the boiler.
1. Connect the system return marked “Boiler Return”.
2. Connect the system supply marked “Boiler Supply”.
3. Install a purge and balance valve or shut o valve and drain on the 
system return to purge air out of each zone.
4. Install a back ow preventer on the cold feed make-up water line.
5. Install a pressure reducing valve on the cold feed make-up water 
line (15 psi nominal on the system return). This boiler has a maximum 
working pressure of 160 psi. You may order a higher pressure relief 
valve kit from the factory. Check temperature and pressure gauge 
when operating. It should read a minimum pressure of 12 psi.
6. Install a circulator as shown in Applications (this manual). Make 
sure the circulator is properly sized for the system and friction loss.
7. Install an expansion tank on the system supply. Consult the 
expansion tank manufacturer’s instruction manual (see Part 4, 
Section D for water volume) for specic information relating to 
expansion tank installation. Size the expansion tank for the required 
system volume and capacity.
8. Install an air elimination device on the system supply.
9. Install a drain valve at the lowest point of the system. Note: The 
boiler cannot be drained completely of water without purging the 
unit with an air pressure of 15 PSI.
10. The relief valve and temperature and pressure gauge are included 
in the accessory kit. A discharge line should be installed 6” above the 
drain in the event of a pressure relief. The pipe size must be the same 
size as the relief valve outlet. NEVER BLOCK THE OUTLET OF THE 
SAFETY RELIEF VALVE.










