HVACopediaNavien · Boiler · Other
Air handler contacts open (NHB-H)
What happens, in order
- Boiler is running with the air handler interface enabled (PCB DIP switch bank 2, switch 7 ON)
- Air handler contacts (A/H) close only while the boiler is doing space heating on a thermostat call
- A/H contacts open when the thermostat is turned off
- A/H contacts open while the boiler is making domestic hot water or is waiting in standby for a DHW call
- A/H contacts open on a level 2 or higher error
- A/H contacts open when the boiler is switched off
Applies to: NHB-H condensing boilers
Models
NHB-H
Related
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Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Navien NHB-H installation manual, air handler interface section. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.