HRV trumps "fan only" mode?

Has anybody heard of a situation where the HRV would take the place of the furnace fan only mode? My client’s seller is saying the builder by-passed the thermostat’s fan on only setting. To me they should run independant of each other. I’m guessing the seller or whoever upgraded the thermostat (nice new programmable) wired it wrong.



Are they saying the thermostat will not turn the fan on at all? I agree with you. All the new installations I have seen have a separate switch, usually a timer, that controls the furnace fan in addition to the switch on the thermostat.

Not quite Stephen. Just to confirm/clarify - furnace fan came on in heat mode (thermostat’s fan switch in AUTO mode), but not in MANUAL fan only mode.

I have heard of set ups where the HRV when on, will turn the furnace fan on at low speed (DC motor Hi Eff.)

I believe the Manual Fan setting on the thermostat should turn on the furnace fan regardless of the presence of the HRV.


I agree, it got wired improperly.

Thermostat when set on auto should activate the furnace circulation fan when there is a demand in heat/cool mode, when set on ON it should activate the furnace circulation fan (on low speed if equipped with two or more speed) and HRV should activate the furnace circulation fan when activated.

Many times I see the thermostat On switch not wired/connected, also the HRV not interconnected with the furnace fan.

Thanks Marcel.

Is this an HP/AC thermostat used to control a heating furnace only?

No, it’s a common heat/AC non-programmable thermostat. A/C installed.