Sirs,

I have a HEIL Model H9MPD125L20C2 furnace. When the furnace comes on the air is very cool. In the manual it states that there is a 30 second delay for the fan to come after the furnace ignites which seems correct. I would like to adjust the time the fan comes on from 30 sec to say 45 seconds. How do I do this or is there now way to change the manufacturers preset time.

Thanks you,

Cliff Schmalzigan

The end-of-cycle off-delay is adjustable on most electronic furnace controls, but the preheat on-delay is typically fixed to conform to design operating temperatures. Older mechanical fan/limit combos allowed the on and off temperatures to be adjusted.

The delay switch is located on the furnace module. Usually a slide switch of sorts.

If you can adjust it and your high temp limit switch starts tripping you'll know you need to switch it back. The 30 second interval may be there to prevent overheating.