Furnace Exhaust Fan Turning On And Off

Exhaust fan should only run when the furnace is on.

Furnace exhaust fan turning on and off.

If the thermostat clicks on i can hear. So if your furnace keeps turning off and on too quickly your thermostat might be malfunctioning or broken. I have a problem with a 15 year old heil natural gas furnace that is connected to a honeywell ct3500 thermostat. The wiring could be old and need replacing it might need new batteries or it could be the location of your thermostat.

This happens only with the thermostat not calling for heat or cooling. Part of an interactive video. There is either an electronic or a vacuum limit switch that turns the exhaust fan on when there is a call for heat. A properly sized furnace should turn on and off between three and eight times per hour deepening on the characteristics of your house outside air temperatures and other variables.

This was an interesting call on their exhaust fans that kept turning on and off after a power outtage. Nest e cycling furnace exhaust fan during cooling cycle just installed a new nest e and had to run the ac for the first time today. The electronic limit switches are disc shaped and mounted on the exhaust pipe at the. One of the limit switches is locked in the open position so the fan runs continuously.

The exhaust fan turns on first a second limit switch senses the fan is on the sends a signal to the control board and the furnace turns on. Your thermostat is what controls your entire heating system. Stack exchange network consists of 176 q a communities including stack overflow the largest most trusted online community for developers to learn share their knowledge. Despite what you are told if your furnace is turning on and off more than eight times per hour this does not mean that it is short cycling.

There are several things that could be causing your thermostat to not work properly. Clean the fan after turning off your furnace completely examine the fan for dirt and debris and clean it if necessary. The system uses a temperature probe to detect temperature changes inside the heat exchanger see image below and turns your blower on and off in response. This will help you diagnose the issue and know exactly where to start looking.

My new youtube hvacr tool review channel link https. If your blower is constantly turning on off when the furnace isn t heating you most likely have a bad fan limit switch. The exhaust fan will run for a few seconds then turn off for a few seconds. It might just mean that it is cold outside is sized a little small or you need some more insulation.

Why does my high eff gas furnace exhaust run constantly when furnace isn t on the furnace turns on and off a few times before running then the blower comes on. The inducer exhaust fan cycles on and off about 10 15 seconds on then shuts off then immediately cycles on again extremely annoying and not exactly silent either. While your furnace is powered on take a look at how your fan is running to see if you can pinpoint exactly where the noise is coming from.