gas fireplace not lighting properly

**Jerry Peck** · 11-17-2012, 07:35 AM

Starting a new thread here so it is in the proper forum for it.

This is from the previous thread so we all know the what, where, when, why, etc.:

Originally Posted by Jerry Peck

Similar problem happened last weekend with our remote operated gas fireplace - the pilot comes on, then shuts off, the main burner does not open.

I talked to the gas fireplace people and they all say it is likely the thermocouple not heating up and thus shutting the main burner gas valve off before it opens.

I ordered a pilot assembly (which includes the thermocouple) form them, cost $50.

I will replace that pilot assembly when it comes in, if that does not correct the problem I will call them and let them check it and see what else it might be.

Guys, we are in the wrong business - they charge $75 for a service call ... which includes the first *15 minutes* only!

Originally Posted by Brandon Whitmore

Jerry,

E-mail me, or start a new thread-- I can probably help you out.....
PS: In my area, the gas company service tech's come out and do diagnostics& minor repairs for free for any gas equipment...........

Barndon,

Let's start here with the help as it may help others too.

Similar Threads:

**Brandon Whitmore** · 11-17-2012, 03:46 PM

I'll start out with some assumptions, so correct me if I'm wrong.....

You've got a fireplace that doesn't have a standing pilot. You call for heat/flame, the spark ignitor starts clicking, and then the pilot lights.

After several seconds of being lit, the flame cuts back out on the pilot, and the burner never comes on.

I will assume you have a flame rectification based system, and will try to simplify this just to get your fireplace working......

At the pilot, you should have a pilot hood (spot where pilot flame comes out), an ignitor/sparker, and another small rod that the pilot flame hits-- is that correct so far?

I'll assume that your pilot is still nice and sharp/ blue, and is hitting this small rod (flame rod/flame proving rod/flame sensor). If not, the pilot needs to be disassembled and cleaned out. ---- I doubt that your pilot is the issue.

In my experience, 9 times out of 10, you have a flame rod issue.
Access the control box (box typically under fireplace where wires plug in). Find the wire plugged into the box labeled as "sense/FS" or something similar. If you can't read the marks on the terminals, then trace the wire from this rod near the pilot back to the box.

Then, get a multi- meter that has a DC micro amp setting that can read in 1/10th increments in micro amps. Un-plug the flame rod wire at the box connect the multi- meter test leads in series with the flame rod wire and teminal at the box.

Turn on the multi- meter, make sure you have good connections, and then fire your fireplace. You should get a reading of up to about 6-8 micro amps if your flame sensor is good (guess- they vary), but I've been able to get a fireplace burner to kick on with as little as a .2 micro amp reading. My guess is that you will find a reading of 00.0 micro amps if the burner isn't kicking on.

If you have the 0 micro- amp reading with everything hooked up, you either have a dirty flame sensor, or flame sensor wire issue. The last one I worked on I had a 00.0 reading until I pushed on the wire up near where it enters the fireplace. While wiggling and pushing on the wire, I'd get a 00.2 reading, and the burner would then kick on.

Next step:

Attempting to clean the dirty flame rod......

1)Pull the fireplace glass
2)Carefully remove the logs/ material from the fireplace so there's good access to the pilot/flame rod/ ignitor assembly.
3)Find a crisp dollar bill, or 100 dollar bill if you're made of money (manufacturer approved method) and and use it to clean the flame rod (kind of like using a towel on a pole). Don't use anything course to clean the rod- damage may occur.
4)Clean the pilot assembly.
5)Leave the glass and logs out. Re- fire the fireplace and take another reading with the multi meter. My guess is that the burner will fire and show a decent micro amp reading unless you have a wire issue (doubtful).

This also works on furnaces. If an inshot burner furnace fires and burns for about 5 seconds before kicking off, you usually have a flame sensor issue. The dollar bill trick works wonders. The flame rod for furnaces will be at the far end burner-- it ensures that all burners fire in order to prevent delayed ignition issues. The white "silica" stuff naturally found in natural gas leaves a film on the rod, at least that's my understanding.....

**Jerry Peck** · 11-17-2012, 05:29 PM

Originally Posted by Brandon Whitmore

You've got a fireplace that doesn't have a standing pilot. You call for heat/flame, the spark ignitor starts clicking, and then the pilot lights.

After several seconds of being lit, the flame cuts back out on the pilot, and the burner never comes on.

Correct so far.

The pilot lights after several clicks, the main burner knob starts to turn on (remote operation function), barely turns toward on then turns back off and the pilot goes out.

I can manually turn the main gas burner knob to on and the fireplace lights, then shuts itself off and shuts the pilot off.

I will assume you have a flame rectification based system, and will try to simplify this just to get your fireplace working......

At the pilot, you should have a pilot hood (spot where pilot flame comes out), an ignitor/sparker, and another small rod that the pilot flame hits-- is that correct so far?

Similar, but not quite.

There is no pilot hood. The instructions show two types of pilots: a) which resembles more of what you are describing, but still without the hood, for natural gas where the thermocouple is out in the flame; b) for propane, which we have, where the thermocouple is fixed (welded) to the tube the pilot flame comes out of.

I'll assume that your pilot is still nice and sharp/ blue, and is hitting this small rod (flame rod/flame proving rod/flame sensor). If not, the pilot needs to be disassembled and cleaned out. ---- I doubt that your pilot is the issue.

The pilot is not nice and sharp/blue, it bends upward and has a yellow tip, the small rod (the thermocouple) is not in the flame, it is fixed to the side of the tube the pilot comes out of, that tube is supposed to heat up which in turn heats up the thermocouple.

I have the entire pilot assembly order and it should be in shortly. This pilot assembly does not come apart, or so it looks and so I was told. From your description, installing the new pilot assembly will be better than cleaning the current pilot assembly, with the result being the same - the fireplace should then work properly. If it does, I will be able to clean the original pilot assembly and save it as a spare in case this happens again.

If replacing the pilot assembly does not work, I will try the other things you say.

Thank you.

**Brandon Whitmore** · 11-17-2012, 11:20 PM

What's the manufacturer/ model number of your fireplace?

The pilot should be able to be pulled apart somehow-- the orifice or pilot head is likely partially plugged, or you wouldn't have that yellow tipped flame.

I'd use a nylon bristle brush to scrub in there somehow& then try to blow if out with compressed air. That usually works. At times, you may have to clean out the actual orifice, which would require the purchase of special tools probably. That, or perhaps a piece of wire from a wire brush may be small enough (doubtful). We use reamers to clean, or a set of miniature hand drill bits to ream out or drill out an orifice.

The thermocouple can be tested, but that requires a 15 dollar part, so it sounds like you may be better off replacing the piece you were already planning on replacing.

Sorry, I thought I may be able to save you a few bucks.

**Brandon Whitmore** · 11-17-2012, 11:25 PM

it is fixed to the side of the tube the pilot comes out of, that tube is supposed to heat up which in turn heats up the thermocouple.

The flame has to hit the top 3/8" - 1/2" of the thermocouple for it to function properly. The t- couple is a bi- metal (usually copper/ nickel--copel)-- heating the tip is what generates the millivoltage. I can't figure out exactly what you are describing, probably because it's a pilot kit for propane instead of natural gas. They should work the same, so I'm stumped as to why there's a different pilot assembly. Typically, the orifice is just a different size.

The fact that you don't have a good pilot flame leads me to believe that may be the issue, or at least it's something to focus on for a start.

**Jerry Peck** · 11-18-2012, 06:39 AM

Originally Posted by Brandon Whitmore

What's the manufacturer/ model number of your fireplace?

I'm out of town now, but I will be back home Thursday and will get that information.

The pilot assembly I ordered should also be in and I will change it out then too.

I'd use a nylon bristle brush to scrub in there somehow& then try to blow if out with compressed air.

I tried cleaning it in place with a vacuum, and I did get a lot of debris out of it, but there was not much working space with it installed.

Once I remove it I can take it to my garage and blow it out with the air compressor.

Sorry, I thought I may be able to save you a few bucks.

You have already. I ordered the replacement pilot assembly before I posted in response to the other thread. If replacing the pilot assembly works, I now know that I can clean them and swap them out as needed. If it does not work, I know some things to do before I call them to check it - and at their service call prices, everything I can do first will save more than a few bucks.

The information was very helpful.

**Jerry Peck** · 11-22-2012, 07:35 PM

Brandon,

I got the fireplace working, here is what happened and what I did:
- removed existing pilot assembly and installed new pilot assembly
- - Huh? Now no pilot?
- in checking to find out why there was no pilot I found a wire with a spade terminal on the end of it which went nowhere, after checking the installation instructions and manual I determined it must be the #2 thermo leg to the switch, placed it in what appeared to be a place for it where the end of the thermocouple screwed into the control assembly, now there was pilot
- tried to light the fireplace with the remote and it worked!

I then took the original pilot assembly to the garage and put it under my lighted magnifying glass/lamp. I found some more debris down in it which I blew out with my air compressor. I also found that the pilot burner tube air slots were crushed in somewhat and that the tube was not round at the end.

I rounded out the tube and re-aligned the air slots, I suspect this pilot assembly will work if I ever need to reinstall it.

I suspect the problem was the loose wire from the thermocouple to the switch - it would make contact and allow the pilot to light, although the debris reduced the flame and likely did not properly heat up the thermocouple, and when the gas valve started to open, the loose wire was giggled, causing the pilot to shut down.

Any way, that is my guess, but it is working properly now. Thank you for your information.