Personal unit heater question

[Inspector 102]

Our municipal building has a 100,000 btu unit heater that is causing me fits. Admittedly I am an inspector, not a mechanical service man. The problem is the igniter will not fire with a heat call. Recently had the igniter module and the gas valve replaced and it worked for 2 days then malfunctioned again. Have had mechanical contractor in the exchange parts and they said they are stumped on the random malfunctioning of the unit. Any suggestions appreciated. I know this is not a DIY site, but I also know the group of people on this forum might be willing to offer some suggestion to what to look at as a problem. Already got the okay to change the entire unit out, but I am stubborn and think this one should work. Only 9 years old, have had problems intermitently for last 3 years.

 

[gbhammer]

Sounds like a candidate for the Thanks giving day massacre. “Alias - Thanks for the great links for trebuchets.”

 

[Gregg Harris]

Do you have a brand and model #?

 

[cda]

My home heater has a thing sticking out where the flame oes through it, forgot waht they call it, but it gets carbon build up on it and will shut the unit down, because it does not believed it fired.

so the solution is to sandpaper the sensor and it starts working

other thins is if your city is not stuck using one hvac company, all another one that might know a little more, or if you are stuck with one company ask for the boss to come fix it.

also had similar problem they replaced the regulator and found out it was the computer baord that was working intermitly

 

[Gregg Harris]

My home heater has a thing sticking out where the flame oes through it, forgot waht they call it, but it gets carbon build up on it and will shut the unit down, because it does not believed it fired.so the solution is to sandpaper the sensor and it starts working

other thins is if your city is not stuck using one hvac company, all another one that might know a little more, or if you are stuck with one company ask for the boss to come fix it.

also had similar problem they replaced the regulator and found out it was the computer baord that was working intermitly

It would be referred to as the "flame rod" "flame sensor" "flame rectification rod" and it measures flame current in DC micro-amps to prove to the gas valve that the flame is burning. If your system is having a consistent problem with the flame sensor needing to be cleaned, find a company that will adjust your system with a combustion analyzer. The easiest way to clean is with electrical contact cleaner.

 

[cda]

Thanks Gregg

Going to fix it good , replace the whole system, very old and yearly problem lately