Furnace keeps stopping during operation...

dbldee20 · 01-23-2011, 03:35 PM

I have a newer high efficiency Comfort Maker, about 5yrs old. The intake & exhaust are vented directly to outside. I'm pretty sure the problem is not not with thermostat. Furnace kicks on after thermostat calls for heat, it runs for a few min then stops. reignites, runs, stops over & over until it eventually stops. It sounds like the blower stops running but there is still some electrical noise coming from furnace after the blower stops. It was doing this earlier in the winter, I changed batteries on thermostat and changed furnace filter and the problem seemed to go away. it recently got very cold here in western PA (low temp around 5 over night) and thats when I noticed the problem again.

The thermostat temp is accurate and coincides with another thermometer in the house. The house reaches desired temp eventually, but furnace keeps shutting down for 30 secs or so while in operation, then restarts. It may do it 7or 8 times before shutting down for a while.

Any feed back is appreciated

**beenthere** · 01-23-2011, 05:26 PM

Is your air filter dirty.

dbldee20 · 01-23-2011, 06:58 PM

No. I pulled it out and checked it already. Its only a month or so old

Dwoodsmith · 01-23-2011, 07:07 PM

I'm not an HVAC guy , but I think that's almost certainly the fan motor or the capacitor. The capacitor is very cheap and easy to replace comparatively, so try that first. Grainger has them. When the fan motor went out on mine(on the coldest day of couse), I could still get it to kick on for a few minutes if I spun the fan around by hand. I replaced it myself and I will tell you those guys that do that deserve every penny and more. It took me almost all day. The easiest part of the whole project was getting exactly what I needed, and a little advice, from the store I mentioned before.

dbldee20 · 01-24-2011, 08:45 AM

Thanks for the info. Hopefully it isn't the blower motor. The furnace is still pretty new, considering my old one lasted 24 years. The blower works, but like I said the whole furnace shuts down for short periods. I'll look into the capacitor

kayostar · 01-24-2011, 06:00 PM

It does sound like it may be the capacitor that is causing the problem. If it is not check to make sure the burner ports are not damaged because they may also be causing the intermittent fault.

portable furnace

bgabrielse · 01-24-2011, 06:36 PM

is it draining water?

dbldee20 · 01-24-2011, 07:17 PM

there is no water draining onto the floor. I do have a humidifier mounted to the return air side. the excess water gets pumped into utility sink after it passed thru water filter in humidifier. The furnace runs normally for 4/5 min after initial start up then shuts down repeatedly. Almost immediately after stopping, (within 30 secs) it will relight and kick back on again.

zootjeff · 01-24-2011, 07:26 PM

Quote:

Originally Posted by dbldee20

there is no water draining onto the floor. I do have a humidifier mounted to the return air side. the excess water gets pumped into utility sink after it passed thru water filter in humidifier. The furnace runs normally for 4/5 min after initial start up then shuts down repeatedly. Almost immediately after stopping, (within 30 secs) it will relight and kick back on again.

My Trane was doing this. It turned out to be the exhaust blower's drain plugged with gunk. You could also hear the water in the fan noise if you put your ear up to the unit. I pulled off a drain hose from the blower and all this water came out. Problem solved..

-Jeff

dbldee20 · 01-28-2011, 09:12 AM

I had a hvac guy check it out. turns out the gas pressure was too high. he made an adjustment inside the furnace and it fixed the problem. He said the furnace was running too hot from excessive gas and it was triggering a switch when the heat exchanger got too hot and told the furnace to shut down.

the guy who installed it had adjusted the pressure because it was having problems lighting sometimes. this was 3 years ago, not sure why it took so long for the problem to arise. problem fixed for $100 service call.

**beenthere** · 01-29-2011, 07:07 AM

Could be your A/C coil is dirty if you have central A/C on the furnace.

Some techs will adjust the gas pressure lower then it should be to stop a furnace from tripping its limit. Because its easier then fixing the real problem. not saying thats what was done here, but its possible.

dbldee20 · 01-29-2011, 10:28 AM

Im not sure if the AC coil is dirty. I do have central AC on the furnace. Both the furnace and AC were installed new in 2006 at the same time. Is it likely that it would be dirty after that period? How would I know, is it something I could clean myself?

I actually spoke too soon. It started doing it again the day after HVAC guy fixed it. Although its not as bad and only shutting down once or twice during operation now.

**beenthere** · 01-29-2011, 10:32 AM

A/C coil can get that dirty in less then 2 years.

If you can get to the air inlet side of the coil, yes you can clean it yourself.

dbldee20 · 01-29-2011, 11:25 AM

It looks like the front panel may come off. Not sure. There is a separate panel where the lines come in and a larger panel around it. There is a patch on the back where the humidifier was originally mounted that I could easily remove. Do I use a vacuum to clean it?

**beenthere** · 01-29-2011, 12:01 PM

Inside the panel will be the coil. But you need to be able to gt to the inside/bottom of the coil. There is a plate that has to come off. And then you can vacuum, and after that chemical clean it. Simple green works.