NGC garage heater malfunction.

[drdwb]

If we have any experts in natural gas garage heaters I’d appreciate assistance in trouble shooting.
It’s a 22 year old Hamilton WGH 30-45 series model.
Last year I walked into garage and noticed the smell similar to burning electrical component almost like when a ballast goes bad, I smelled around and couldn’t find source, I have multiple fluorescent lights so I assumed one was going. Unplugged everything and within a day smell was gone. I did not notice any heating problems, garage is kept around 35-40 degrees.
I noticed the smell again 2 weeks ago, unplugged all checked lights problem resolved.
Until today, I was in the shop all day yesterday and today ( maybe you’ve heard about our Midwest snow storm) so noting to do and a warm shop project time.
Yesterday everything fine, left heat up all night returned this AM no problem, until around noon, I went in for quick lunch came back out and noticed a weird gurgling sound come in from heater, but no fan running, I spend quite a bit of time out there and have never heard this before. So I turned down thermostat and shut breaker off, waited 1/2 hour turned up thermostat and heard click than gurgling sound again.and the burnt electrical smell was present. So used air compressor and blew everything out I could. Turned back on, while shooting air in and heard burner kick in but no fan, which usually runs briefly before burner kicks in. So I’m thinking bad fan. Find number on fan check local joints still open in snow storm, no luck, turn thermostat down and breaker off, go into house to look up Amazon to find replacement, But I’m questioning this as the fan was fine yesterday and until noon. When I come back out I had the idea to put a fan behind the heater to force air through until I get replacement, but before I got the fan hung up I turned thermostat back up, It works, WTF. Still hung little fan behind and the heaters been running normally. So I’m thinking possibilities, 1 Flame roll out switch, faulty Hot Surface Flame Ignitor, or faulty Flame sensor.

So if you have expertise or experience with this type of heater and have managed to wade through this narrative and have suggestions to eliminate one component or another feel free to add your thought. I suppose it could be a faulty circuit board as well or something like a crack in the heater core.
 
Thanks for any and all ideas.
Dave

[RinkRat II]

     The only thing I have to offer on this is that the gas pipe inlet should have a drip leg before the shut off valve and I would check that for moisture or foreign objects that may have made their way into the control valve. My $.02

      Paul B 

[fotoguzzi]

I got nothing but suggest you get a carbon monoxide detector. I just got a new one for my garage.

[Mike Tashjian]

Owners manuals usually have troubleshooting information.  I would also read on how the unit operates under normal conditions. Almost any part that is not working right will shut the unit down for safety reasons. You will have to find out what part or parts that is.  I have made it a habit to clean and inspect my gas furnace annually and the direct vent units periodically.  That way I have a pretty good idea what may be wrong when a unit goes down.  I have found units that have pilots that are shut down for the summer can have spider issues in the pilot area and the main orifice. So I do not shut mine down any more.

[pressureangle]

I'm no expert, but it could be a burned capacitor (as is very common in A/C condenser fans) that would account for the smell and the intermittent no-start. One way to diagnose is to turn the system on and find the fan faulted; give it a spin with a stick and if it starts and runs it's likely the 'start' capacitor. Also check the wires attached to the capacitor, they can corrode and burn away.

[guzziart]

I got nothing but suggest you get a carbon monoxide detector. I just got a new one for my garage.

 

[John A]

+1 on the start capacitor. A visual after you find it might show something. It’s good to have a start and a run capacitor on a shelf somewhere. That way you’ll never need one…

[StuCorpe]

I always keep a "start" (or run I'm not sure which is the correct terminology) capacitor on hand.  I've replaced them in 2 furnaces (mine and my daughters) and one well pump.  The last time I went in to get a new replacement the counter guy said "This one is good, they never fail" and I just ignored him as when I had put the replacement in it started running and this was the one I had taken out.  The only way to test them is by replacement.

[John A]

I was trying to remember electrical stuff. It seems to me that from the foggy depths of time , I learned that on heaters and air conditioners a bad capacitor can take out the power relay or vice versa . Any way I ran across this utube that xplanes electrical stuff so even I can understand some of it , maybe it’ll help https://youtu.be/sq0rv80mV9Q

[s1120]

+1 on the start capacitor. A visual after you find it might show something. It’s good to have a start and a run capacitor on a shelf somewhere. That way you’ll never need one…

Ya, every time I had one go you could tell just by looking at it. They are pretty cheap also if you can find a supply house that sell them.

[nsmith]

It's called a run capacitor and there is a way to test them but depending on the fan motor you might not even have a run capacitor. Then again you might. It would make sense it being bad. any poor electrical connection could do the same. You said the fire kicks in so ignitor, flame sensor, gas valve, transformer, tstat are most likely working. fan relay, wiring, are suspect. Oh and when replacing any run capacitor the uF rating should be the same as the original unless you want to replace the motor next week. If you do replace the motor you should always replace the run capacitor. Good luck.