Update all fixed thanks natural gas fireplaces

[wwbirds]

Not that we use it much but was installed when we built house and we liked the convenience of not having to haul wood into house.
Stopped working when we hit the wall switch a few (12?) years ago and when I replaced switch all was fine for 10 years. Havent tried turning it on until last week and nothing. Replaced switch as that was the fix that worked last time but still nothing. pulled ceramic imitation logs out and I have a pilot light but no burner flame. flipping new or old switch makes no difference.
Not a high priority (used 4 or 5 times in past 10 years) but if it is a simple fix I will try any suggestions.
thanks
Rob

[urban rednek]

Could be the low voltage transformer that powers the gas valve is kaput. Check for voltage at the gas valve connections.
Could be the gas valve itself, but they are generally bullet proof.

ETA- what Dean said. Thinking back, the low voltage transformer in mine was for the blower fan.

[Dean2]

Not that we use it much but was installed when we built house and we liked the convenience of not having to haul wood into house.
Stopped working when we hit the wall switch a few (12?) years ago and when I replaced switch all was fine for 10 years. Havent tried turning it on until last week and nothing. Replaced switch as that was the fix that worked last time but still nothing. pulled ceramic imitation logs out and I have a pilot light but no burner flame. flipping new or old switch makes no difference.
Not a high priority (used 4 or 5 times in past 10 years) but if it is a simple fix I will try any suggestions.
thanks
Rob

I know this is pretty basic but I always find starting at the beginning and going through the steps helps many times. Did you make sure gas is on on the main pipe control and the red gas control knob for the fireplace itself. If it has a permanent pilot light, you need to switch gas control to pilot, push it in, light pilot. Then make sure switch is turned to burner. With pilot lit, check for current at the switch on the two wires that come from the fireplace. They only run on tiny voltage to the wall switch. If there is no voltage on the two wires, and they are connected at the fireplace properly then the thermopile that sits in the pilot and generates the micro voltage needs to be replaced.

If there is voltage there and when the cwitch is close to send it to the gas control, check the gas control valve/switch.

[Okotok]

Is the pilot light burning? If so and the main burner isn't coming on then try replacing the thermocouple. If it isn't then light the pilot, turn the knob to main burner and then turn on the wall switch.

Edit: Dean2 posted at the same time.

[Dean2]

Is the pilot light burning? If so and the main burner isn't coming on then try replacing the thermocouple. If it isn't then light the pilot, turn the knob to main burner and then turn on the wall switch.

Edit: Dean2 posted at the same time.

If the pilot stays lit, the thermocouple is fine. Thermocouple only controls gas for the pilot itself.

[Okotok]

If the pilot stays lit, the thermocouple is fine. Thermocouple only controls gas for the pilot itself.

Doh! You're right. If the pilot goes out when you release the button, then the thermocouple is toast or loose at the valve.

[CaberTosser]

Thermopile lads, thermopile, not a thermocouple.

In most gas fireplaces its a thermopile powering the gas control valve rather than any outside power. I have seen some more recent gas fireplaces that did have 24V power but I thought that was pretty dumb as it negates the most important feature of them functioning as a back-up heat source when the power is down.

When lighting them, be sure to hold the pilot button down for about 30 seconds or so, the reason for this is to allow the thermopile sufficient time to heat up and start generating power so it can hold the power unit open (the power unit being a tiny electromagnet that holds the gas valve open against the spring that is perpetually trying to shut the gas off). Often, a pilot light burner might need cleaning to burn a bit hotter, which will generate more power at the thermopile. Dust & lint accumulation can affect the air pre-mix venturi @ the burner and have the flame burning red/lower temp rather than blue/higher temp. Insufficient power from the thermopile is often a result of a weak pilot flame rather than a bad thermopile, but both can happen. In my experience perhaps 65% weak/dirty flame to 35% bad thermopile.

The light switch was a good step, as those are often problematic. Light switches being designed for 120V and a fireplace being roughly 500mV, a bit of tarnish on the switch contacts can be enough resistance to prevent function for a 500mV current.

[Dean2]

Thermopile lads, thermopile, not a thermocouple.

In most gas fireplaces its a thermopile powering the gas control valve rather than any outside power. I have seen some more recent gas fireplaces that did have 24V power but I thought that was pretty dumb as it negates the most important feature of them functioning as a back-up heat source when the power is down.

When lighting them, be sure to hold the pilot button down for about 30 seconds or so, the reason for this is to allow the thermopile sufficient time to heat up and start generating power so it can hold the power unit open (the power unit being a tiny electromagnet that holds the gas valve open against the spring that is perpetually trying to shut the gas off). Often, a pilot light burner might need cleaning to burn a bit hotter, which will generate more power at the thermopile. Dust & lint accumulation can affect the air pre-mix venturi @ the burner and have the flame burning red/lower temp rather than blue/higher temp. Insufficient power from the thermopile is often a result of a weak pilot flame rather than a bad thermopile, but both can happen. In my experience perhaps 65% weak/dirty flame to 35% bad thermopile.

The light switch was a good step, as those are often problematic. Light switches being designed for 120V and a fireplace being roughly 500mV, a bit of tarnish on the switch contacts can be enough resistance to prevent function for a 500mV current.
I agree and it is what I said. You did however provide an excellent discussion of how a weak pilot flame can affect voltage generated. You always provide great detailed explanations.

[wwbirds]

first thing was remove service panel which revealed the user instructions (all in french). Turned off what I thought was a very strong pilot light (some yellow though which caber has told me in past is not a good sign, want blue)
full vacuum of a lot of dust some of which probably has been there since house was built in 1993. then washed and wiped all surfaces and took a fine pin to gas pilot jet. Upon relighting pilot I had two nice blue flames but switch still didnt work or make anything happen. Pulled switch touched two wires together and still nothing however when I rubbed the two wires together my wife said a flame started and then stopped. held together again and flames was stronger second time around. Put wires back on switch and tried it several times while putting it back in wall and all working each time. thanks again!!