Furnace staying stuck in pre-ignition

pittscop105

I have an HB Smith gas furnace. Recently the furnace becomes hung up in pre-ignition and just the hot surface ignition glows bright orange but does not ignite the furnace so it just continues to run until I turn off the furnace switch and turn it back on. The furnace will then run fine but then gets hung up again the next time there is call for heat or to run the hot water tank. This used to only happen once in awhile but now is happening more frequently on a daily basis. Any suggestions?

STEVEusaPA

Well it is a safety device, best to leave the troubleshooting to a competent tech.

JohnNY

Check your air pressure switch and its hose connections for blockages.

pittscop105

I have no intentions of trying to repair this myself (Ha ha), I've had my HVAC guy there a couple of times and am looking for other ideas to give him to find a solution. I appreciate the two comments thus far.

JUGHNE

In most of the systems I have worked on, they will not go to ignition at all if the air switches are not satisfied.
The next step after ignitor glowing would be gas pilot or main burner on. No fire or no gas... the ignitor would still shut off and retry and eventually lock out.

All of this is controlled by the board which is the brains for the sequence of operation. That would be my first guess.
If the gas valve is getting 24 volts and not opening then that would be the 2nd item. IMO

Please let us know the outcome.

SuperTech

I would bet it's either a problem with the ignition module or the gas valve itself. If you are getting 24 volts to the gas valve after the igniter glows and no ignition then it's likely a bad gas valve. If the the igniter glows and no voltage to the valve then I would replace the ignition module.

HVACNUT

Your calling it a furnace but say it hangs up to run the heat or water tank which would indicate a boiler.
Can you post a pic of the "appliance" and the wiring diagram?
Sometimes the HSI will energize depending on model, regardless. Its isolated from the 24v burner circuit and is doing what its told to do on a heat demand. If theres gas there, terrific. If not, that's why theres a flame rectifier.

EBEBRATT-Ed

Most time the air switch will not allow ignition but it is a possibility. Most likely the control board or the gas valve

mikeg2015

HVACNUT said:

Your calling it a furnace but say it hangs up to run the heat or water tank which would indicate a boiler.

Can you post a pic of the "appliance" and the wiring diagram?

Sometimes the HSI will energize depending on model, regardless. Its isolated from the 24v burner circuit and is doing what its told to do on a heat demand. If theres gas there, terrific. If not, that's why theres a flame rectifier.

A lot of folks call boilers “furnaces”. It’s confusion. I think I’v seen boilers call water heaters too. I dont think HB smith ever made a hot air furnace, so it’s a boiler.

We have one of our customers with a “flakey” ignition. It’s either a bad gas valve or a bad control board. If you get 24VAC to the valve, then it’s the board. IF not, probably the board. This is assuming you are getting a pilot. If not, check 24VAC to the pilot.

rick in Alaska

You might also check to see if the condensate is backing up, assuming it is a high efficiency furnace. That can also stop it from firing as it will stop the pressure switches from opening up the gas valve.
Rick

Tim McElwain

What are the make and model numbers of the controls on the boiler? Once I know that I can tell you were to start.

John Mills_5

Smith used HSIs on atmospheric boilers too. I'd say control.