8 About the Boiler
General Specifications
Item NHB-055 NHB-080 NHB-110 NHB-150
Dimensions 17in (W) x 12in (D) x 24in (H) 17in (W) x 13in (D) x 24in (H)
Weight 73 lb (33 kg) 80 lb (36 kg)
Installation Type Indoor Wall-Hung
Venting Type Forced Draft Direct Vent
Ignition Electronic Ignition
Natural Gas Supply Pressure (from source) 3.5 in–10.5 in WC
Propane Gas Supply Pressure (from source) 8.0 in–13.5 in WC
Natural Gas Manifold Pressure -0.03 in WC -0.08 in WC -0.10 in WC -0.40 in WC
Propane Gas Manifold Pressure -0.03 in WC -0.07 in WC -0.09 in WC -0.30 in WC
Gas Connection Size 3/4 in NPT
Power Supply
Main Supply 120V AC, 60Hz
Maximum Power
Consumption Less than 10 amperes
Materials Casing Cold-rolled carbon steel
Heat Exchangers Primary and Secondary: Stainless Steel
Venting
Exhaust 2 in or 3 in PVC, CPVC, approved polypropylene*
2 in or 3 in Special Gas Vent Type BH (Class III, A/B/C)
Intake 2 in or 3 in PVC, CPVC, polypropylene
2 in or 3 in Special Gas Vent Type BH (Class III, A/B/C)
Vent Clearance 0 in to combustibles
Safety Devices
Flame Rod, APS, Ignition Operation Detector
Water Temperature High Limit Switch, Exhaust Temperature High Limit Sensor, Water
Pressure Sensor
*Approved polypropylene systems include:
●Durevent Polypro (Single Wall): 2PPS-xxx (2”), 3PPS-xxx (3”)
●Centrotherm Innoflue SW: ISxx02xx (2”), ISxx03xx (3”)
Refer to manufacturer’s literature for detailed information.
Note This unit may be installed at an altitude of 10,100 ft (3,078 m) for natural gas, and at 4,500 ft (1,370 m) for propane. Refer to“6.
Setting the DIP Switches”on page 48 to correctly adjust the altitude settings. At altitudes above 2,000 ft (610 m), the boiler’s
rating will reduce by 4% for each 1,000 ft (305 m) gain in altitude.
Temperature Setting Range
Item Temperature Setting Range Remarks
Space Heating
Supply 77–194°F (25-90°C) Actual supply and return temperatures vary
depending on the selected outdoor reset
curve.
Return 68–158°F (20-70°C)
Note For more information about the space heating temperature setting range, refer to“Setting the Heat Load for the Outdoor Reset
Control Mode” on page 60.
