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Nest Thermostat - Humidifier and blower running even when furnace is not running

ColoradoSkip
Community Member

I have a new HVAC system with an Aprilaire humidifier. I have seen this issue posted before but no solution. Humidifier and blower keep running after furnace shuts off even though humidity is above set % and blow cold air. Runs almost continously. 

I want humidifier to run only when furnace is on since running continously is costing money when not needed

1 REPLY 1

kirk-467
Community Member

This issue usually happens when the humidifier is wired to run independently of the furnace instead of only when there’s a heat call. That can cause the blower to keep running and push cold air even when the furnace is off. Ask your installer to check the wiring to the W (heat) call, confirm the humidistat is set to run only with heat, and make sure no fan-activation settings are turned on. Once it’s set up correctly, the humidifier should run only when the furnace is heating.