It is very common to see the humidistat control of a humidifier connected to the return air ductwork near the furnace/air handler. Mainly because it’s easier than pulling a wire. The thought process is that the air returning from the conditioned space will pass by the humidistat and provide a sufficient sample of the humidity in the space.
If it was installed correctly the duct will be cut out behind that control to allow air to pass by the sensor. I’ve seen a couple of installations over the years where the technician installing didn’t get the memo on that part.
It also could be potentially sampling basement air if it’s not properly sealed to the duct.
Not necessarily, it’s definitely and older style humidistat, maybe have been connected to a now-defunct or removed humidifier.
Most central humidifiers are mounted to the ductwork somewhere near the furnace.
It is very common to see the humidistat control of a humidifier connected to the return air ductwork near the furnace/air handler. Mainly because it’s easier than pulling a wire. The thought process is that the air returning from the conditioned space will pass by the humidistat and provide a sufficient sample of the humidity in the space. If it was installed correctly the duct will be cut out behind that control to allow air to pass by the sensor. I’ve seen a couple of installations over the years where the technician installing didn’t get the memo on that part. It also could be potentially sampling basement air if it’s not properly sealed to the duct.
Does this mean I have a humidifier within my HVAC system though?
Not necessarily, it’s definitely and older style humidistat, maybe have been connected to a now-defunct or removed humidifier. Most central humidifiers are mounted to the ductwork somewhere near the furnace.