Gas Fireplace won't stay lit

[Shorticus]

I`ve noticed the past two times I used my natural gas fireplace, the main burner extinguishes its flame. Runs for a few minutes until it gets hot enough for the blower to kick in, but then shortly after it goes out, comes back on within 10 secs, and repeats the cycle every few minutes

I`ve done all the usual checks (fuel supply, clean the burner, check the venting, wire connections, etc)

However, I suspect the most probable cause is the high temperature limit switch or bad thermocouple but have no idea how to test it.

Anyone with experience with these that can tell me how or can point me in the right direction in case I'm way off base. Could it be a leak in the seal on the front glass as well? (Doubt it as it's fairly snug once in place)

Thoughts?

If it helps, its a Heat-N-Glo Model SL-550TR-C

[TKG26]

Does the pilot go out?

A vent limit switch will take out the pilot. If its your main burner only going on and off, it can be:
-bad wire connections(they get loose eat up voltage
-bad switch(had one yesteday with a 50mv drop accross the switch)
-dirty pilot= low voltage
-weak powerpile...

Ill check the manuals out later to see if you have a powerpile with thermocouple or just a powerpile.

[Shorticus]

Thanks TKG.

No, the pilot stays lit. It re-ignites the burner within a few seconds.

The manual mentions a thermocouple, so I'd say yes to that question.

Also, I'm not sure how far I can take this myself and notice you're in Ottawa. Do you do this for a living and/or have a company locally you'd refer (I'm in the West end, Stittsville)

[TKG26]

I work for Direct Energy, don't do side jobs, but if your calling your looking at Diagnostic fee(99$) plus parts and labor if needed.(ask for a cleaning its a bit more but we will give the thing a proper going over and clean the thing(glass,burners,logs ect), we can diagnose the problem at the same time)

If yours has a thermocouple and the pilot is not going out, then it also has a powerpile which is the voltage source for the main burner and is controlled buy your switch or thermostat.

We are split up into areas and i dont do the Stittsville area. mostly ottawa and south

If you look at your pilot you should see, the flame hitting 2 things a thick powerpile and a thin thermocouple and you will also see the manual ignitor next to the pilot.

How is your burner controlled? Switch or thermostat? Many times its a switch with high resistance....

[dosborne]

You may want to check for buildup on the powerpile and/or thermocouple. These should be cleaned regularly. Also ensure the flame hits these properly. This can cause the burner to shutdown. Particularly if it runs a while, then shuts off.

Every couple of years it may be worth your wile to schedule a maintenance vist to have it properly cleaned and aligned although it isn't big deal doing it yourself. Fortunately, the safety mechanisms kick in if you do anything wrong

[Phatboyc]

You can sand the powerpile. Sometimes when being off all summer creates oxidation. If that fails I would change the powerpile.

From my experience don't call the big companies for service. Try to find a local one where you deal with the owner directly or almost. Two years ago I needed a whole new valve. Which I knew was broken.

The big company said they had to send someone make a diagnostic first. 100$ latter "Yep you need a new valve sir". The week after I call them to see if they received it. "Sorry sir we can't find a replacement valve for you, nothing else we can do."

I ended up calling a smaller company. Asked me which model I had and ordered a replacement valve. They came to my house once with the part and install it.

[TKG26]

Any build up on a powerpile is usually from a dirty pilot flame. Sanding to clean is find but if the pilot hood and orifice is plugged with dirt its not going run reliably. On some units its simple job of a clip and a hex key to dismantle and properly clean a pilot, on others its alot more involved in removing and taking apart the pilot assembly right down to the oriface... Its not a DIY job.

Play it safe and have a licensed GasFitter look at it.

[Battscrew]

I had the same problem - my fireplace has 2 switches - one on the wall and one in the fireplace itself - when I turned on the fireplace with the switch inside the fireplace - no issue. When I used the wall switch, I had the same issue as you.

The wall switch was a standard 120v light switch. Swapped it out with a new one and no problem.

From what i understand the standard 120v light switch is not the proper method as they develop some type of resistance over time - but builders use them because they are cheap.

[TKG26]

Battscrew: You got it, the typical 120v switch when new can last for a few years, but later on there resistance builds and will give u issues. A simple swap to a new switch is all that is needed in many cases. The switch on the unit its self usually last much longer supposed gold contacts but i replace my fair share of these as well.

[Shorticus]

Hey guys.... thanks for all the help.

I worked kind of backwards. I ran a test using a voltmeter on the high temp switch to see if it was shutting it down (however, with the standing pilot working I wasn't convinced this was it)

when it cut out, there wasn't any voltage change, so that switch checks out.

I pulled it apart, got into the guts and ran some sandpaper over the thermopile and the thermocouple. They were both pretty dirty. Ran it again not problems but its not consistent (It has run once or twice before without going out)

TKG26, its switch controlled and not thermostat.

Battscrew, I think you're onto something. My house is 7 years old and the builder used a standard wall switch. I have a box of them in the basement. If it happens again (should know in a day or two), I'll switch it out and see if I can recreate the problem.

When it went out this morning (before the sanding/cleaning) it didn't cut back in as usual. I flipped the wall switch, and presto it came back on. It also runs fine on the fireplace switch you mentioned.

If the switch is the problem, I should see the switch running at 120 volts and drop to zero if it kicks out? I'm I correct in thinking that?

[TKG26]

you will be reading dc millivolt, acceptible voltage drop would be no more then 0-5mv. if u get 10-30mv on a closed switch its time to change it. i see this a lot on 5uear old plis units where tje 120v rated switch starts to get resistance.

[Shorticus]

Well.... I did see a change of around 10-12mv. Now, without trusting that, I picked up a new switch and installed it this morning.

So far, 2 for 2 in working correctly. I'll be running it again over the next few days and will post an update on the status.

thanks everyone for your help/advice so far.

[Shorticus]

Well it ran for 4 days with 6 tests and no problem. Appears to have been a bum wall switch.

Thanks to everyone who helped out.

[d_j1s]

I just realized today that it might be a switch problem.
Try this:
Turn on the fireplace with the switch. In my case, the fire did not go on.
This time, I left the switch on and tapped it. The fire came on.
My guess is that the tapping burnished the contacts just enough to overcome the resistance for the low current from the thermopile.

[57]

As discussed a couple of weeks ago... Suggest you replace the switch, use it a few times, or get a better one.

http://www.digitalhome.ca/forum/show...60#post1003160 Posts 32, 33, etc.