Wednesday, March 12, 2014

Pilot Light On Gas Logs Won'T Stay Lit With Logs On



We have just purchased vent free gas logs; with the logs off the pilot light will stay lit and the flame will work; with the logs on the pilot light goes out.
Call center representative at manufacturer said not enough gas pressure; gas company says plenty of pressure - we operate two furnaces and a gas dryer with that pressure; gas company says no way gas logs would need more than furnace.
any suggestions?

Originally Posted by pmcmahon
We have just purchased vent free gas logs; with the logs off the pilot light will stay lit and the flame will work; with the logs on the pilot light goes out.
Call center representative at manufacturer said not enough gas pressure; gas company says plenty of pressure - we operate two furnaces and a gas dryer with that pressure; gas company says no way gas logs would need more than furnace.
any suggestions?
What you have is nuisance shutdown. All of the components work or else you would not be able to initially establish the pilot.
Low gas inlet pressure would be one possibility, but it appears that you have ample evidence that other products perform well under the same conditions (although the ODS pilot is much more tempermental than the pilot on a furnace or water heater).
It could be as simple as adjusting the pilot screw on the valve (if equipped) to allow more gas to flow to the pilot, to removing any drafts, or as difficult as a poor product design. What is occuring is that the main burner flame is drawing the pilot flame away from the thermocouple. The thermocouple cools down, stops creating millivoltage that energizes the magnet in the valve that is holding the plunger that you engaged with it when you pressed in on the knob while initially lighting the pilot, and releases the spring-loaded plunger, which stops the flow of gas to the main burner and pilot.
Most valves have a pilot adjustment screw that if you turn it counter-clockwise you increase the gas flow to the pilot, causing a stronger flame to counteract the pull of the main burner flame.
Drafts caused by fresh air inlets in the firebox, blower or ceiling fan could pull the flame off of the thermocouple.
Poor design is such that the ODS pilot was positioned in such a manner that the pilot flame is not strong enough, no matter the pilot adjustment setting, to overcome the pull of the main burner. Some manufacturers are better than others in designing products. The design may pass the laboratory tests to gain certfication per the unvented heater standard ANSI Z21.11.2, but the designs are not real world friendly. My sympathies to you if this ends up being your case.
I hope this helps.
Rett Rasmussen
Vice President
Rasmussen Gas Logs Grills
Welcome to Rasmussen Gas Logs Solaire Infrared Grills - Time to Tailgate!

Originally Posted by pmcmahon
We have just purchased vent free gas logs; with the logs off the pilot light will stay lit and the flame will work; with the logs on the pilot light goes out.
Call center representative at manufacturer said not enough gas pressure; gas company says plenty of pressure - we operate two furnaces and a gas dryer with that pressure; gas company says no way gas logs would need more than furnace.
any suggestions?
I am not a pro yet! I am taking heating and air classes at the local CC. I have taken the gas heating class and I have a set of vent free gas logs.
Some of the clues in your post raise a red flag to me. You have two gas furnaces and a clothes drier. Do you also have a gas water heater and oven? It is possible to have too many gas appliances in a home. Oxygen for these comes from the inside of the house. If the house is too tight, fresh air can't replace combustion air fast enough. If more air is burned than can be replaced, oxygen levels in the house can become depleted. With the reduction in oxygen comes an increase in carbon monoxide. The manual for your logs has a section for calculating the maximum gas BTU consumption you home can support. This is the reason for the oxygen depletion sensor or ODS. For these reasons the ODS's parts have critical placement. The pilot flame is also critical in that it should just touch the thermocouple. You should not adjust anything on an ODS.
You said the pilot goes out when the burner is on. Does the pilot go out immediately or after a while. If the pilot goes out after a while the ODS may be doing what it was designed to do. In this case, you have a very dangerous condition that must be remedied. If the pilot goes out immediately, you may well have a pressure problem. Try turning off all other appliances. Also ensure that all valves on the line are fully open. A partially closed valve will allow enough flow for the pilot but not enough for the burner.

Is your pilot full and strong with the main burner off and does the pilot become smaller when you turn on the main burner. If that is happening, then you have a volume issue, not a pressure issue. You need a professional to do a pressure test on the gas logs both with and without the main burner on. If the pressure drops when the main is on, then you either have an obstruction in the gas line or just not enough CFM of gas to supply all of your gas appliances. They should also turn on the other appliances while making this test.

Originally Posted by rettras
What you have is nuisance shutdown. All of the components work or else you would not be able to initially establish the pilot.
I have a very similar problem, but I think it should be less complex. My gas logs worked great for 3 years (Rasmussen Chillbuster C5a). This season however, they have been very hard to light, hard to keep lit, and have displayed the symptoms listed by the OP where the pilot will burn all day and when I light the burner it goes out within a few minutes. I have usually been able to relight them, but I have to hold the button in until I get PILOT imprinted on my thumb......and it takes several tries for several minutes to get success. Even then, burn time is somewhat random, might burn all day, might be 15 minutes.
It was my thought that the thermocouple was tired and needed to be replaced.....at least until I read this. Since nothing else changed in our setup and we have no other gas appliances, I wouldn't think much else could be the culprit.
Before I order a $130 part.....I thought I should check and see if I'm missing something.

Originally Posted by amaxey
I have a very similar problem, but I think it should be less complex. My gas logs worked great for 3 years (Rasmussen Chillbuster C5a). This season however, they have been very hard to light, hard to keep lit, and have displayed the symptoms listed by the OP where the pilot will burn all day and when I light the burner it goes out within a few minutes. I have usually been able to relight them, but I have to hold the button in until I get PILOT imprinted on my thumb......and it takes several tries for several minutes to get success. Even then, burn time is somewhat random, might burn all day, might be 15 minutes.
It was my thought that the thermocouple was tired and needed to be replaced.....at least until I read this. Since nothing else changed in our setup and we have no other gas appliances, I wouldn't think much else could be the culprit.
Before I order a $130 part.....I thought I should check and see if I'm missing something.
I had a similar problem with my pilot going out.
Got out the vacuum brush and a handy-dandy pipe cleaner.
Clean the pilot with the pipe cleaner. There probably is even a draft hole set back a bit from the pilot burn area, cleaning mine has fixed it all now.
fred

sounds like volume remark is right on check supply line from shutoff to logs, may be to small, distance from gas meter is a issure and are your logs on the end of line ( do all other appliances get their gas first )

I had this same problem, with a few more quirks but basically the same. No rhyme or reason to how long it would burn but the pilot might stay on for days by itself. Went to clean the pilot with a pipe cleaner and realized there was a little pebble (from under the logs) in the pilot assembly. Did some minor surgery to get the pebble out and everything worked fine since.






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