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  1. #1
    Join Date
    Jan 2005

    majestic dual thermopile issues

    I came across a problem with my own fireplace Majestic M#RFSDV34RFN dual thermopile input to a honeywell gas valve. I am looking for literature on the the control board on that gas valve, I first noticed the length of time it would take to open and light the main flame (slight delay) then it would bring the fan on then shut it off right away, ok so I check the thermopile readings #1 is at450mv(wires disconnected) #2 is at 350mv disconnected, I checked the terminals now that they are back hooked up again #1 is at about 380mv, #2 is at 250mv with main flame and fan on, what are the minimun mv readings required to maintain smooth operation, in the mean time I just swapped the leads between powerpiles and it runs great,but I suspect the powerpile with the lower out of the 2 readings is the problem,any thoughts

  2. #2
    Join Date
    Nov 2005
    London, Ontario, Canada
    I learned the hard way on that unit. If you think the valve is the problem , think again. I had good readings on both but 1 had an intermittent short in it and messed me up. Buy 2 new t-piles and replace them before thinking of the valve. Remember the t-piles are polarity sensitive on that valve.

  3. #3
    Join Date
    Jan 2005
    As per one of my previous posts , I believe Hearthman stated these systems require a min. of 500mv open circuit on both thermopiles and that they are polarity sensitve, white leads to white dots on terminals.

  4. #4
    Join Date
    Feb 2004


    Do the simple thing first, make sure the pilot is clean and is properly adjusted. That may be all you need to bring the mv right up.
    Question authority!

  5. #5
    Join Date
    Jan 2006
    Majestic has a tech support book which covers this valve in length I suggest gettting a hold of them for it. The book is in my work truck atm and am unable to remeber the title and such. It covers all the vavles and most problems. One thing though is the blinking light codes are pretty vague, have a hard time figuring it all out.

    I work with a tech that claims to have replaced all kinds of these valves gonna have to mention the polarity issue.

    I had one encounter which I told the customer unfortunately I had no replacement batteries in my truck but would still have to charge for the call out there (cleaned the bugger up nice).

    One side note though soaping this valve is very hazardus to the life of it they tell you to use a sniffer.

    I will try to post the name of the book on monday.

  6. #6
    Join Date
    Mar 2005
    The RFN valve has a self diagnostic feature and will give you a flashing code when problems occur. both Thermopiles must read within 100 mv of each other. if you have one that is weaker the valve will malfunction. look for 3 flashes of the little red L.E.D ;light this will indicate a thermopile problem. replace both thermopiles at the same time. never replace only one. also be very carefull removing the pilot assy if you have the 1/8 inch pilot tube. it will break off at the brass ferrul very easily.

  7. #7
    Join Date
    Jun 2011
    Fresno, CA
    So came across 3 of these units and went into extensive lengths with tech support about operation etc... whoever posted up 500mv is right, tech said the same thing, working on one

    right now that was converted to propane and the pilot due to restriction/pressure issues exploded/released pressure after installing 2 new thermopiles polarity sensitive like explained

    above just use your little mirror and reference the bottom of the valve to line up the thermopile connections. So the first two systems that I came across it was the valve and no

    matter I did the led would blink normal/no error code fan would ramp up and on and nada. So tested pressure/mv/valve/remote to no avail nothing. Called tech to verify what

    I did and it was pretty much a expensive conversation which bummed me out, who wants to tell a customer that the valve is no longer available and that you'll have to do a complete

    change out valve/pilot assembly or get a new unit? So this system that I am working on now was pretty surprised that is was in working order until the pilot hood blew. Initally when I

    showed up the system had servere sooting/no visible signs of pilot tube/hood failure when I let it sequence for 20 minutes heard a loud pop and a small fire under the pilot cap where

    it was not suppose to be): Haven't went back to perform the whole assembly change out because their supply pressure to that unit and another lennox in the bedroom were off and

    they are waiting for the propane supplier to bump it up/check out the issue. So my opinion on this system is that they f'ed up on putting a remote/board/valve all in one. Who wants

    to just go off a LED light to change thermopiles, change them and still back at square one. So going to have that cut your losses talk with the homeowner before I order the part, and

    let them make the choice to invest in the old system or a new one.

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