I have A Heil Furnace that starts up just fine Model #NDG1075DFo1, but after its running for 5 minutes or so it gets another call for heat, fills the gas box with naatural gas and re-lights this mix pretty violently. This may happen a few times during the heating cycle until the thermostat is satisfied and shuts the unit down. There is nothing wrong with the thermostat as I have jumpered it out to eliminate it as a cause. Is it the valve or the control board. Any help would be greatly appreaciated as it feels like it is going to blow up one of these days
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Part one of the problem I think is the furnace is over heating and limmiting out. As far as the delayed combustion you are experiencing, I need to know more about what type of ignition it has, ie. standing pilot, auto pilot, direct spark hot surface ignition I don't know enough about that model number.

Oh, did you read the FAQ sticky at top of main HVAC page for more answers?

whats the serial # on this 80%eff 75,000 btu furnace

Part one of the problem I think is the furnace is over heating and limmiting out. As far as the delayed combustion you are experiencing, I need to know more about what type of ignition it has, ie. standing pilot, auto pilot, direct spark hot surface ignition I don't know enough about that model number.


This furnace has direct spark hot surface ignition. The furnace is cutting out and relighting I think because the flame sensor may not be seeing the flame on the burner or the pressure switch may be bad . Does any of this make any sense? Thanks for the Help.

i have seen on two units this winter, same model, where your pressure switch hose connects to draft inducer housing, restricted. Pull hose off and run paper clip in port a couple of times, and reconnect hose, the port sometimes gets a little rust build up.

Does anybodt out there know where the pressure switch is on a Hiel Furnace . It is a downdraft model with direct spark hot surface ignition Model # NDG1075DF01.Thanks in advance

I can't say exactly, but there should be a small hose coming out to a round flat thing between the heat exchanger and the inducer blower.

What is the proper way to direct the condensation tubes to prevent water leaking?