[cliff43]

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

[KC13]

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.

[hvac1000]

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

[dac122]

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.