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, i.e.. 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?

What's 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?

I,am still waiting for an answer??

I have a 2005 Heil Furnace H9MPD075F12B1 The inducer has been replaced 2-3times. The code is 6 flashes + 1 flash = soft lockout. I replaced the inducer again just because the service guy said the bearing was starting to go-loud whining noise. This time that did not do the trick. The same code still appears.Lance I am going to try cleaning flame sensor rod