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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Plus90 furnace with an newly upgraded control

Customer Question

I have a Bryant Plus90 furnace with an newly upgraded control board. Humidifier is connected to R and Com, but there is always 24v at the humidistat, even after the furnace shuts down. Shouldn't that be 0 v. when the furnace shuts down? The water is always running unless I turn the humidistat off.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


These can be wired in many different ways, and those vary with the particular model of furnace, and if it has a communicating thermostat or a more common standard non communicating thermostat, it can take hours to sort this out.

The primary issues are the blower must be running whenever the water solenoid valve on the humidifier is energized AND the outside air temperature should be below 60F (lacking that you can have the humidifier running in cooling mode).

Your offer will not cover that much work on my end, let me know if you are interested in additional service offer that will cover 2 hours of my time or not.

We can go from there or I can opt out to a host of other HVAC experts on the site.

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