Servicing a propane fireplace

Here is a schematic I found of a typical fireplace gas control valve. Mods, I obtained this one from Regency fireplaces to show some technical labeling. It shows the smaller port for the thermocouple, not to be confused with the bigger port for the pilot light. Mine is similar but the port for thermocouple is at 90 degrees to the gas port for the pilot light.

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Me again. I removed the end of the thermocouple from the gas valve and using a multimeter with one lead on the end of the thermocouple and the other end about a foot away on its copper tube. I then lit the pilot flame and watched the multimeter start to climb to 8 mV and stay there, which is much less than the 25 required to keep the gas from shutting off. Time to get the thermal couple out of its holder. I undit two screws on the plate but there is little room to access the nut hiding the thermocouple in place.

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It really looks like you only need to clean / adjust the pilot burner so that one of the three jet flames actually touches the thermocouple. Right now it is too short and off to the side. The thermocouple needs to be enveloped in flame to get hot enough.

Start by, as someone else said, spring out the wire clip and pull the burner head up and off.
 
It really looks like you only need to clean / adjust the pilot burner so that one of the three jet flames actually touches the thermocouple. Right now it is too short and off to the side. The thermocouple needs to be enveloped in flame to get hot enough.

Start by, as someone else said, spring out the wire clip and pull the burner head up and off.
I pulled the clip and removed the burner head. I ran a pin across inside of the head. The head is indexed to aim one of the three jets at the thermocouple and one jet at the thermopile. The third jet just points off in space between the two.
 
It really looks like you only need to clean / adjust the pilot burner so that one of the three jet flames actually touches the thermocouple. Right now it is too short and off to the side. The thermocouple needs to be enveloped in flame to get hot enough.

Start by, as someone else said, spring out the wire clip and pull the burner head up and off.
Although I did’t see any gunk I put the head back on and now I have three string jets. The thermocouple is reading 19 mV, much closer to the desired 25 mV.

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Here is what it looks like with the metal clip removed. The head pulled off easily. I didn’t see any blockage but the flame is now better. Rookie tip: The clip will get deformed a bit but bend it back in shape then install in in the bottom half, then push the head back on and the clip will spring into position, holding down the head.

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The top of the pilot light head is hitting the frame of the fire place and the absolutely rigid burner.

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An update on this. The rather massive cast iron burner was held in place buy two small screws but man was it solid. I removed the screws, moved the burner head by moving it to the left, unbending the wire that is used to function the air inlet adjuster and simply pulled it up and away. I now have full access to the plate that has the igniter, thermocouple, thermopile and pilot burner. Power on!
 
I was able to work on the plate that holds the igniter, thermocouple, thermopile and pilot light head. With everything pulled apart I decided to order up a new thermocouple from Amazon. Should be here next week. The fireplace is cosmetically back together waiting on a new thermocouple. Thanks for everyone’s help.
 
that what is supposed to look like.. GOOD JOB.. we would charged 180 buck to clean the pilot, check/ clean thermocouple and thermopile, clean logs, clean glass, replace wool for "burning embers" look..


Although I did’t see any gunk I put the head back on and now I have three string jets. The thermocouple is reading 19 mV, much closer to the desired 25 mV.

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I installed the new thermocouple. It fit perfectly. The tip now glows red and the flame stays on only after a few seconds. I turned the knob to on and put the controller on “ thermostat”. The fireplace works perfectly and is controlled by the wall thermostat. When it warms up a bit, the fan comes on. The on/off of the fan is controlled by a wall switch and the speed is controlled by a knob at the base of the fireplace. Thanks everyone for your help with this.
 
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Not for fireplace but I had a LP pool heater. The thermocouple would need to put enough MV to open the pilot light gas tube/valve and then main gas valve. I had to replace that a couple times.

My wife's cousin has a NG boiler same scenario. The thermocouple went bad a couple times not keeping pilot lit. The last time I did it the plumbing supply house didn't want to sell me it so "un-qualified/un-licensed" user didn't play with gas and go boom. I had already traced through and metered all the safety's and all were good. Only issues was Pilot would not stay lit. 2 choices at that point, thermocouple or main gas valve which is a PITA to change and expensive. Home Depot did have the thermocouple, I bought 3. The other 2 on her boiler room wall just in case for future. Not expensive as stated.

Maybe some YT videos now on how to change that on your brand easiest?
I hear you. And actually there was no case when I had to break a connection that had gas travelling through it. I have to admit though, the small gas line from the gas valve to the pilot looks similar to the line of the thermocouple except the gas line was aluminum and the thermocouple line was copper. I imagine someone could break the gas line connection by accident.
 
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Good flame impingement on thermocouple and thermopile and the thermocouple tip is glowing red. If the fireplace doesn’t have those conditions it will be difficult to keep it on. Thanks for all the good advice.

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Here’s a shot with the fireplace logs back in place, the glass front back on, and the doors closed. From a certain angle you can see the pilot light. If the thermocouple tip is glowing you know it is set up correctly.

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I had one last issue ( hopefully). The digital thermostat failed to ignite the fireplace. I pulled the cover of it off the wall and replaced the two triple A batteries. They were reading 1.48 V. I replaced them with two new ones that read 1.52 C. It works gain. I was was surprised the small drop in voltage was enough to cause issues. Maybe it was just the contact points. Works reliably again.
 
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