Heater Help

[Booth]

I installed a used ADP 45,000 BTU heater in my garage last week. I had a couple issues with it, but resoved all of them. Yesterday it started shutting off on me. I get a LED code of 4 flashes; it translates to High limit or Rollout switch open.

What does that mean in non HVAC terms.
Many thanks,
Paul

 

[D KRAGER]

High limit would mean that the plenum is getting too hot. There is a temperature sensor so that if the fan motor fails and the plenum gets too hot, sensor will shut the system down.

Is the fan blowing air the way it should?

Are you using the correct gas? LP or nat gas?

 

[Booth]

I am using the correct gas NG. The fan is turning. I took the cap off the B-Vent t and got a little dust out of it. After I did that turned the heater back on and so far shes working... I think it has somthing to do with the chimney maybe. I hope its not the heat exchanger. I am installing a CO2 detector in there after I get done typing. I don't know it frustrating! If it happenes again I suppose I'll have to call a guy.
Thanks,
Paul

 

[texasOFT]

My house central heater furnace fan can be wired for 3 different speeds - you might check to see if yours can be wired for a higher speed which would reduce the heat exchanger temperature.

 

[Booth]

Well I figured it out! Its the board, to be exact one of the male conector tabs. The solder is loose.

So the heater would kick on, run and vibrate enough that the tab would come loose from the board. That would shut the fan off and the heat exchangers would get too hot... and that is what would cause the limit switch to trip. After it shut down the tab would fall back into place and it would run again.

The board is coming out tomorrow and getting a little solder job.

Thanks guys I'm going to bed!!
Paul