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Problem with Majestic gas log fireplace

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by iknownothing, Nov 19, 2005.

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  1. iknownothing

    iknownothing New Member

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    I'm having trouble with a Majestic (model # MBU36) gas log fireplace and hoping someone here could offer some suggestions...

    First, with the knob in the Pilot position and depressed, I can get the pilot to come on, but as soon as I let go (even after holding it depressed for 30-60 seconds), the pilot turns off.

    Occasionally, the pilot will stay on, and I'm able to turn the knob to the ON position. The fireplace comes on for a few seconds, then goes out.

    I've cleaned the tip of the the pilot to remove any dust, etc. and also checked the positioning of the thermocouple and the pilot. All seems fine.

    Could it be that the thermocouple needs replaced? If so, is this relatively easy? I haven't yet seen any how-to's on this topic. Where could I get the thermocouple?

    Thanks.

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  2. webbie

    webbie Seasoned Moderator Staff Member

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    Sounds like it may need replaced - BUT, one other thing to try. This is very low voltage, so is the connection from the thermocouple to the gas valve is not perfect, there will be problems.

    So, assuming you are handy, remove the nut that holds the thermocouple to the gas valve (no gas flows through this), clean the threads - someone told me a pencil eraser works good for this, and then re-assemble and tighten fairly well...but not too tight.

    Then try it again...report back....
  3. iknownothing

    iknownothing New Member

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    Thanks Craig. I will give it a shot.

    Just wanted to add that the fireplace is about 9 years old now.
  4. iknownothing

    iknownothing New Member

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    Hi Craig,

    I did what you recommended, and got excited at first because it seemed to work! The fireplace stayed on for a about 5-7 minutes, then went out again.

    What I did was remove the thermocouple, cleaned the thread (it was pretty clean to begin with), wiped the thermocouple tip, and reassembled it. The pilot stayed on when I lit it this time, and the fireplace came on, but only for a few minutes.

    Does this indicate I need to replace the thermocouple? If so, where do I get it from? I did a few searches but didn't seem to find any sources.

    Thanks again!
  5. webbie

    webbie Seasoned Moderator Staff Member

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    Well, at least the cleaning showed that would have helped (if thermocouple was good)....

    You can often find these at plumbing and heating stores (these places usually have a"counter" and accept walk-in traffic.

    I know that Woodman Associates (the big parts place) has a lot of these. Check the link to them at:
    http://www.hearth.com/prod.html

    Also, if you go to a P & H outfit, bring your old one. Woodmans might know by either the gas valve model or label or the fireplace type. I think most of these are fairly similar, the exception being "thermopiles" , which are larger and generate more electric. Most newer stoves use these - you'll notice they often have a larger pilot because of this.
  6. webbie

    webbie Seasoned Moderator Staff Member

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    Note, don't think this is your fireplace style, but note that certain fireplaces use multiple sensors including "overheat" ones that shut down when unit gets too hot...

    again, because of your earlier problem, this does not seem to relate to your situation, but troubleshooting from afar is always tough.

    In the case of a unit that DID have this second sensor, if it was defective it could possible ALWAYS shut the fireplace down.

    But yours does sound like the regular thermocouple, especially since that cleaning helped it a little!
  7. seaken

    seaken Minister of Fire

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    You said the fireplace is an MBU36. This is not a gas fireplace but a wood fireplace that can accept a log set as an alternative to burning wood. In this case, it is way too risky to suggest anything other than to call in a local professional technician who can safely diagnose your problem. If you don't understand the gas log set and what makes it work, and work safely, you should not be servicing it yourself. We can't even tell from here that it is a vented set. Someone may have put a ventless set of logs in there.

    Please be careful. Your life is at stake.

    Sean
  8. iknownothing

    iknownothing New Member

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    Sean,

    I appreciate your concern. To answer your questions, the unit is a top-vented one. This fireplace came with a new home we had built in 1996. You're correct about MBU36. I need to figure out what the model number is for the gas log unit.

    Thanks.
  9. seaken

    seaken Minister of Fire

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    Is the builder still around? Did you get any manuals? The log set is probably an after market product not made by the same manufacturer as the MBU36. A qualified gas technician can help. Maybe some tea and cookies and a small remunaration will help solve the problem.

    Sean
  10. iknownothing

    iknownothing New Member

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    Ok, I finally got an exact replacement thermocouple and installed it. At first, the pilot started much easier so I thought the problem was fixed. Turned on the fireplace and thought that was the end of it. But no, it turned off again after about 5-7 minutes. Tried a couple more times but still the same problem. I have no idea why this is happening. :(
  11. iknownothing

    iknownothing New Member

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    Anyone have any ideas on what to do next?
  12. Shane

    Shane Minister of Fire

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    I'd have a pro look at it the valve may be defective.
  13. iknownothing

    iknownothing New Member

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    Thanks. Do you know if that is very costly to repair?
  14. sideview

    sideview New Member

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    I've got a similar fire to you, and have had the same problem for 12 years. I've had at least 3 Corgi registered peolpe look at it. I have had the thermocouple cleaned twice. And then replaced. And rearranged the logs many times. Nothing works. What I want to do is remove the stupid pilot light. And have a gas tap with on and off. Like we used to have. And light the fire with a match. It would be quite safe. I wouldn't leave it on if I went out. I hate gadgets.

    But all Corgi registered people say they couldn't possibly fit this for me."Because of regulations".

    I live in south Buckinghamshire. Anybody know any gas plumbers with some common sense who don't care about daft Health & Safety regulations, or European Community rules?
  15. Gooserider

    Gooserider Mod Emeritus

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    Probably somewheres in the $40-50 range, about the same as the labor charge a plumber will hit you with to change it, they aren't that expensive. HOWEVER this is NOT A JOB FOR AMATEURS! Gas is nasty, it has a tendency to go boom, so you want to hire a pro to fix it for you. (Not that that is a guarantee either, I had a pro change a defective from factory gas valve in our H/W heater that left the pipe to the pilot loose, at least we could have sued if I hadn't caught the problem first and made them come back to verify that I had fixed it properly.....)

    Nope, and I doubt you'll find any since you are asking for them to do something that is NOT safe, and that if anything ever happenned would cost them seriously both from a liability standpoint and from loosing their licenses and jobs... You could probably get the stuff to do it yourself, but then that would be asking you to accept the responsibility and cost of repairs if it was ever noticed.

    Gooserider
  16. GVA

    GVA Minister of Fire

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    You know it really su@%s when people start a post and never finish it.....
    IKNOWNOTHING, sorry missed this thread but your situation sounds like Shane said, either bad gas valve or possible High temp cutoff....

    So what did you find?
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