I have a Therompride OL-16 oil furnace with an Aprilaire 560 whole house humidifier. It has a sensor on the blower motor that closes when the blower is running. The swirch does not close so I get no water to the humidifier. The 24V AC current for the comes from a relay wired directly to 110v. The current sensing switch on the blower cost $20-30. A local parts man told me that I could eliminate the switch and hook the water solnoid directly to the 24 V AC on the thermostat relay (R and C of five contacts) which would open the water valve when the thermostat asks for heat. This means the water would not run until the furnace heat kicks the blower on and would not run during the "post burn" cycle of the blower that recovers the residual heat. The parts guy said hunidifiers today were wired this way. Would this work? Would it cause other problems?
This is an oil furnace with an add on electric AC unit.