Problem with Natural Gas Fireplace

[NelsonQ]

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 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?

Thoughts?

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

 

[aspeck]

Re: Problem with Natural Gas Fireplace

No experience with that problem, but I know Rubber Frog has had a problem with natural gas ... maybe he can help!

 

[Drowned Rat]

Re: Problem with Natural Gas Fireplace

I've had to replace the remote sensor for exactly that problem before. The fireplace would also just come on at random times and then go back out. I discovered it by turning the remote operation off and then it worked fine.

 

[mthieme]

Re: Problem with Natural Gas Fireplace

I had this exact same problem on my furnace last season. Fortunately, there is a decent trouble-shooting section int he manual. I had to replace the control board. I assume you don't have this on a fireplace, but there should be a sensor - which is common on commercial HVAC applications.
SS Mayfloat may be able to help you with this one...he got me over another hump with my furnace recently.

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

I had this exact same problem on my furnace last season. Fortunately, there is a decent trouble-shooting section int he manual. I had to replace the control board. I assume you don't have this on a fireplace, but there should be a sensor - which is common on commercial HVAC applications.
SS Mayfloat may be able to help you with this one...he got me over another hump with my furnace recently.

Thanks everyone for your replies. In the 'troubleshooting' section it indicates to check and replace the high temperature limit switch as one of the 8 options. I assume this is the sensor you're referencing.

But, they simply say replace but not how to verify if that is one of the 8 problems.

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

I've had to replace the remote sensor for exactly that problem before. The fireplace would also just come on at random times and then go back out. I discovered it by turning the remote operation off and then it worked fine.

Mine is off as it's wired direct to a switch on the wall.

 

[SS MAYFLOAT]

Re: Problem with Natural Gas Fireplace

Not exactly sure how your igniter system is set up. If it has a thermocouple (standing pilot), make sure that it is in the direct path of the pilot flame. It maybe needs replaced if it is correctly positioned. These are very inexpensive and an easy fix. If it has an electronic ignition, make sure that the burner flame comes in contact with the flame sensor. A flame is conductive and will allow electricity to flow through it, thus completing the circuit. Your description of the problem tells me that your having a problem of showing a proof of flame. If the sensor loses the proof, the main gas valve will shut down. This is major safety feature that is required on all gas fired appliances. The hi-limit is a last resort safety. Usually it will shut down the complete unit. Not seeing it or having a schematic makes it tough to troubleshoot. Good luck......SS

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

Not exactly sure how your igniter system is set up. If it has a thermocouple (standing pilot), make sure that it is in the direct path of the pilot flame. It maybe needs replaced if it is correctly positioned. These are very inexpensive and an easy fix. If it has an electronic ignition, make sure that the burner flame comes in contact with the flame sensor. A flame is conductive and will allow electricity to flow through it, thus completing the circuit. Your description of the problem tells me that your having a problem of showing a proof of flame. If the sensor loses the proof, the main gas valve will shut down. This is major safety feature that is required on all gas fired appliances. The hi-limit is a last resort safety. Usually it will shut down the complete unit. Not seeing it or having a schematic makes it tough to troubleshoot. Good luck......SS

Thanks SS. It does have a thermocouple as you've mentioned. Its wired direct to a wall switch. Flick the switch, and within a fraction of a second, the burner is lit up and burning.

Once running for several minutes and hot enough for the blower to kick in (which it does), poof, out goes the flame (pilot remains lit). Within 3-5 seconds, its back on.

That is why I'm leaning towards the hi-limit as you've also mentioned.

Here is a schematic Figure 17, Page 27

Note however that it doesn't include in that figure the blower I have attached as well.

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

One other question. I called to have a gas tech come out and look at it. $100 for the trip, $100/hr labour (1 hour minimum) plus parts.

Is that reasonable? I'm in $200 before he even starts? Gonna call a few places first.

 

[SS MAYFLOAT]

Re: Problem with Natural Gas Fireplace

I can't say if that is a good price or not since I do all my own work. I work for a resturant chain, so I don't do any billing .

I looked at the schematic, but I need to know if you have the standing pilot, DSI direct spark ignition, or IPI intermittent ignition.

I need to know this to help you further. Do you know how to use a VOM meter? or have one? Let me know and I will help you with this problem. Hang in there,,,you can do it! .......SS

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

I can't say if that is a good price or not since I do all my own work. I work for a resturant chain, so I don't do any billing .

I looked at the schematic, but I need to know if you have the standing pilot, DSI direct spark ignition, or IPI intermittent ignition.

I need to know this to help you further. Do you know how to use a VOM meter? or have one? Let me know and I will help you with this problem. Hang in there,,,you can do it! .......SS

SS, thanks again. Yup, I got a multimeter and can do the basics, just don't know what those basics are.

When you say standing pilot, are you referring to a constant pilot that stays on? If so, that is what I have and not a spark/electric ignition. So I'm assuming the wall switch simply enables a gas flow to the burner that the pilot then ignites the burner.

I'm on my way home from work in a few and I'll check out the specific manual to see if I can shed more light on your question.

 

[SS MAYFLOAT]

Re: Problem with Natural Gas Fireplace

If you have some alligator clips for your meter leads, they would be helpful. Place your meter on AC volts to measure the 110/120 volts. Put one lead on one side of the hi-limit switch and the other on the other side of the hi-limit switch. When the fireplace is in operation, you should show "O" volts. If it is the hi-llimit kicking out, it should read line voltage (110/120vac) when it shuts down the burner. If it continues to read "0", then it is NOT the hi-limit but it could be the thermopile that is not generating enough millavolts to keep the main burner on. In the manual, it gives a great drawing on how the flame of the pilot should be in relation to the thermocouple and thermopile. The thermocouple is to keep the pilot lit and the thermopile generates millavolts for the main burner. Hope this helps.......SS

BTW, you can check the on/off switch also the same way as you do for the hi-limit.

 

[dolluper]

Re: Problem with Natural Gas Fireplace

Question does your burner stay on when the fan blower starts....or the burner goes out before the fan blower starts

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

If you have some alligator clips for your meter leads, they would be helpful. Place your meter on AC volts to measure the 110/120 volts. Put one lead on one side of the hi-limit switch and the other on the other side of the hi-limit switch. When the fireplace is in operation, you should show "O" volts. If it is the hi-llimit kicking out, it should read line voltage (110/120vac) when it shuts down the burner. If it continues to read "0", then it is NOT the hi-limit but it could be the thermopile that is not generating enough millavolts to keep the main burner on. In the manual, it gives a great drawing on how the flame of the pilot should be in relation to the thermocouple and thermopile. The thermocouple is to keep the pilot lit and the thermopile generates millavolts for the main burner. Hope this helps.......SS

BTW, you can check the on/off switch also the same way as you do for the hi-limit.

SS, thanks so much. By the way, it is a standing pilot ignition system which confirmed last night. I'll be checking this out this evening and grabbing some alligator clips for that purpose today.

My understanding (which may be incorrect) is that if it is the high limit switch, it will also extinguish the pilot but cutting gas supply? Is that the case?

I'll pay close attention when testing but I'm positive the pilot stays lit

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

Question does your burner stay on when the fan blower starts....or the burner goes out before the fan blower starts

I can't remember if the fan kicks in before it happens the first time, but it does happen when the fan is running. (Burns for 5 mins or so, out for 3-5 seconds, back on, etc)

 

[SS MAYFLOAT]

Re: Problem with Natural Gas Fireplace

According to the schematic, the blower is pretty much has it own circuit. It reads the temp and kicks on when it achieves it.

The pilot will remain lit when the hi-limit switch opens. The hi-limit only controls the main gas valve. The thermopile controls the main gas valve, the thermocouple controls the pilot. Both are located at the pilot light. BTW, when checking the hi-limit, you must not remove the wires from it. All the hi-limit does is shut the system down if it overheats. Also check your flue. If it is closed, it can cause the hi-limit to kick out. Could be something in you chimney. May want to check those areas out as well.

Had to stop in and look up parts for work,,,will be back on line later this evening.....SS

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

Aaaaaaarggghhh!

Ok. So I setup the VOM to test the switch.

Chronology

6:50 Turn on fireplace (Reading, 120.6V) (Is that normal because of the blower being in line)
6:58 Blower kicks in, voltage drops (Reading 0 V)
7:21 Blower still running, fireplace still running, BURNER HASN'T DROPPED!

So, the best I can guess at this point is I removed the connector from the temp switch that connects to the main gas valve. It looked damaged. Inspected it but it was fine so plugged it back in.

Then, I wiggled the connectors on each side of the temp switch to make room to connect the alligator clips.

Very possible it was bad connection. I previously wiggled all connectors (except the connectors on the switch)

So, its looking like a bad connection.

Will run for the next hour or so and see if I have the problem re-occur. If not, I'm going to do the same tests the next few days to see if I can recreate.

If nothing else, if this was the problem it saved me many $$$$ and now thanks to you SS, I understand how my fireplace works and how to test it.

More to follow....

 

[dolluper]

Re: Problem with Natural Gas Fireplace

Sometimes being connected WORKS ...by the way hows the weather in your part of Ottawa

 

[NelsonQ]

Re: Problem with Natural Gas Fireplace

Sometimes being connected WORKS ...by the way hows the weather in your part of Ottawa

Well, I'm gonna try it again the next 2-3 days and see if it was simply a loose connection.

I'm in the West end of the city, much warmer over here then the East but we got more fog

 

[dolluper]

Re: Problem with Natural Gas Fireplace

Me in the foggy west also.....Kanataland...it has been a challange driving in the mornings with the 10 foot sight path in front of you