[gnicholson]

I'm having a hard time finding information to diagnose a problem with my garage heater and thought maybe there might be some Heating and Cooling guys that might be able to help. A couple of days ago the heater in my shop was working fine and I shut the breaker off to it after it shut itself off and when I came back the next day to turn it on it wasn't working.

When you turn the breaker on normally you hear a couple of clicks like relays pulling in and then you hear a continuous clicking from the igniter firing about every 1/2 second until you hear the main burner come on. Right now all you hear is the initial click and there's no firing from the igniter. I think the ignition control module turns the pilot and ignitor on at the same timeand when the flame sensor reaches temp turns the gas valve on. So basically I have no ignition. As long as I have power and a signal from the thermostat I would think bad module or possible grounded igniter. I was hoping somebody might have an idea thinking about ordering some parts to have on hand so I can fix this thing when I get back in town

 

[Capt Casey]

Not sure but is there a reset button that has to be pressed for the gas to flow like on a normal furnace...?

It may not allow the igniter to work if there is no fuel? just a shot in the dark so to speak...I'm sure there is a heating person here who knows more than I.

 

[Chris27]

Sounds like the ignition module or sparker is bad. It's basically a spark plug. You can switch it on and then when the igniter tries, light the main burner with a BBQ lighter. This will get it going and then at least you can check everything else. Flame sensor is a common failure point as well. If the flame sensor is the problem, it should try to start 3 times before it locks out and needs to be reset.

 

[LeoP]

When did you clean the pilot(if it has one)light last??

 

[ABodyDust.]

A couple pics of the front and back of this unit would help. So this unit has a 24vac secondary step down transformer that sends 24vac to a thermostat or at least it should have a t stat. From there 24v should travel through safety switches. Then ignition control. Spark, then gas valve, flame sensor then blower. Or maybe it has a control board idk (pics?)

Does this unit have a fan motor on the exhaust pipe at the top? Are you able to access the control panel?

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[ABodyDust.]

Sounds like the ignition module or sparker is bad. It's basically a spark plug. You can switch it on and then when the igniter tries, light the main burner with a BBQ lighter. This will get it going and then at least you can check everything else. Flame sensor is a common failure point as well. If the flame sensor is the problem, it should try to start 3 times before it locks out and needs to be reset.

He stated you hear a continuous clicking. That means the spark ignitor functions as designed

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[Diabel1969]

re read my comment and realized I was in error.. I'd also start with the ignitor. We had a meltdown in one last winter, but that was oil fired hot air..

 

[gnicholson]

A couple pics of the front and back of this unit would help. So this unit has a 24vac secondary step down transformer that sends 24vac to a thermostat or at least it should have a t stat. From there 24v should travel through safety switches. Then ignition control. Spark, then gas valve, flame sensor then blower. Or maybe it has a control board idk (pics?)

Does this unit have a fan motor on the exhaust pipe at the top? Are you able to access the control panel?

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It has a thermostat. I assume that circuit is ok since I hear the initial click when I turn it on. No fan in the exhaust. I would go out with my voltmeter and start checking some of this out if I were at home right now. Those are the only two pictures I have

 

[ABodyDust.]

re read my comment and realized I was in error.. I'd also start with the ignitor. We had a meltdown in one last winter, but that was oil fired hot air..

Your right. Reading while multi tasking. Spark igniters don't usually go bad often. I'd be interested in pics of said unit and components. Allot of the diag depends on if the unit has a control board or just a ignition control

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[gnicholson]

Also I normally hear a constant clicking before the main burner lights is what I meant. I do not hear that now.

 

[ABodyDust.]

Ok when you get time. Check for 24v going to the TH terminal on that Robertshaw ignition control. Im betting the ignition control is bad. There is a superseded part# here is the service manual for the ignition control. It shows wiring and such. Does this unit have a honeywell gas valve with a light on it?

https://store.acpro.com/media/GDB_PDF/PDF_r/robertshaw-780-002-ignition-module-installation-instructions.pdf

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[ABodyDust.]

Read this.

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[e0em9mlc]

Flame sensor...will kill the system if fame is not detected...since you indicated that it tuned itself off in your initial post. Not sure if you meant it turned itself off during normal operation or malfunction. Flame sensor is easy and cheap to replace compared to modules and other components. You may try to clean the sensor to see if the system comes on...most times a flame sensor that's going bad will cycle the system on and off.

Mike

 

[gnicholson]

It turned itself off in normal operation the last time it was working. I then turned the breaker off

 

[gnicholson]

Thanks a bunch for the great info guys

 

[ABodyDust.]

If the unit turned itself off that means it met setpoint or ignition control failed. If the unit did not meet setpoint and turned off due to not sensing flame it would reset when power cycled and start the process again. The unit would fire not sense flame and shutdown in short order. The ignition control is the brain of the unit in this case. Note the manufactures service manual posted.

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[ABodyDust.]

It turned itself off in normal operation the last time it was working. I then turned the breaker off

Sadly most ignition controls like yours don't like the main power being turned on and off. It's better to just turn the t stat up they are simplistic controls with cheap parts and longevity is hit or miss. For instance I had a new honeywell replacement control go bad after one heat cycle. The warranty part still functions as designed.

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[gnicholson]

Which brand controller would you buy?

 

[ABodyDust.]

Which brand controller would you buy?

The superseded part and roll from there. That's after the control has been confirmed bad.

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[gnicholson]

Hey thanks for all the help. It was the controller