I have a 95% efficient Goodman furnace that is less than a year old. It has a Generalaire Model 81 drum humidifier installed on the cold air return. The humidifier drum turns when there is a call for heat. I would like to wire it so that the humidifier will work when I turn on the blower fan manually from the thermostat.

The humidifier is 24 volt and gets its power from the furnace without a transformer. One wire goes from the humidifer to the humidistat. Another from the humidisat to a pressure switch that supplies the 24 v during a call for heat. The other wire from the humidifier goes to the common terminal for thermostat connections in the bottom compartment of the furnace. I am pretty sure this is correct, but I am not looking at it at this moment.

Is there any way to supply the 24 V to the humidifier when the fan is on without a call for heat??? Thanks for any help.