How can I get my old 120V whole house humidifier setup to turn on only when
heat is on?
I have an old General 1040 bypass humidifier with a 120V solenoid, wired to
an ancient Sears 120V humidistat switch.
Right now the humidistat switch AND humidifier are wired to the furnace’s
Therefore, whenever the furnace is on and the humidistat is set above “of
f”, the humidifier runs constantly even when the fan is off. Water runs c
My old Goodman GMP-075 furnace has a 115V HUM terminal. I believe the ratin
g is 1.5A. I’d rather connect the humidistat to the furnace 115V HUM ter
minal, but the Sears humidistat draws 6A. The humidifier solenoid is only 6
watts, so draws only .05A.
Is there any way to draw humidifier solenoid power ONLY from the HUM termin
al, and humidistat power ONLY from house 120V? This would avoid overloading
the HUM terminal, but I don’t know how the humidistat would signal the h
umidifier to flow.
Otherwise, is there another wiring setup that can draw 115V at 7A, and only
kick on when heat is energized?
I see the White-Rodgers 2271-100 humidistat switch only draws .5A, but I’
d rather avoid buying new equipment.