Heater ignition goes on, then off, and then back on

allenbr

I have an American Standard Silver Series Model:AUH1B040A9241AA .The heater will go through the starting cycle ,the ignition will turn on and then go off, the heater will go through the start cycle again, the ignition will go on and stay on. The heater then works fine.

Zman

Has the combustion been checked with an analyzer? How is the gas pressure?

EBEBRATT-Ed

Could have a dirty flame sensor if it is a flame rod. If you know how to remove it and clean it with fine steel wool or a dollar bill it might get you running.

Otherwise you need a service tech

EdTheHeaterMan

I am reading this differently, The ignition is the Hot Surface Igniter. That is the thing that glows orange before the valve opens to let the gas into the burners. I am reading the HSI glows orange then goes out, no flame at all, because the cycle was interrupted before the gas valve opens. Then the cycle starts over... HSI glows orange again and completes the cycle with a flame and proof of ignition.

If this sounds more like your issue, there may be a loose wire somewhere. As the wire continues to get looser the problem will happen more often. Check the thermostat wire connection screw terminals. Also check the wire connections at the thermostat R and W are the heat terminals. You can also try a thing that computer geeks do when they are diagnosing a computer problem. Unplug the multi-wire connectors and plug them back in. (both the 12 pin and 4 pin) If the loose connection is in that plug, then you may resolve the issue with this simple fix.

Look for corrosion on the low voltage connections inside the furnace. The limit circuit is usually a red wire that jumps from button limit switch to button limit switch in a series circuit around the burner box and sometimes into the blower cabinet. Also the combustion fan has some tubes that cause air pressure switches to open and close.

Sometimes condensation forms in the tubes. That condensation (water) will alter how the switch works. Removing the tube and blowing thru it will clear out any water or debris.

Those are some of the things I would check, but be sure to put everything back the way you find it. If all that fails to resolve teh issue, you may need a new control board.

If my description of your problem is different than above, Then you have a different set of issues and I would look elsewhere.

JUGHNE

Ed, from observation of the HSI systems, to me it seems that the HSI, powered by 120 VAC, (except for HW smart valves), glows to a red/orange temp and then the 120 is removed and gas valve opens.
The residual carry over heat of the HSI is what lights the gas.
As soon as the 120 is disconnected that HSI circuit then becomes the flame sensing rectification circuit.

For the OP, I would just change the HSI. They tend to have a short life and having a spare is a prudent move, if that is not the problem. Perhaps the first heat up preheats the HSI and by the second fire the flame sensor conductivity function is improved upon.

IMO, they are not cleanable.
Early HSI's failed because of corrosion build up.
Rheem/Ruud had a recall/correction by adding a flame sensor to the other end of the burner carry over tube. Many years ago....seemed like last year...but was the 90's.

unclejohn

Air pressure switch maybe opening.