Valliant 125 heater will not light

Discussion in 'The Beginner' started by nsr500rossi, Sep 22, 2011.

  1. nsr500rossi

    nsr500rossi Read Only Funster

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    Hi

    Just got my first camper van, an old renault auto sleeper

    I am working through all the things that need to be fixed, i have sorted the fridge and heater but am having trouble getting the boiler to fire up ..

    It is a valiant mag 125/7

    I have the pilot light working and have changed the diaphragm and top housing so it is now leak free.

    But the boiler will not fire ..

    I have the water pressure working

    i have tried removing the water section and manually operated the rod that opens the gas whilst the pilot light is on, but still there is no gas coming from the main jets (if thats what it is called)

    Any ideas, i am a bit stuck

    many thanks

    Mike
     
  2. pappajohn

    pappajohn Funster Life Member

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    Hi Mike and welcome....

    three possibilities spring to mind.

    1) faulty thermocouple.....the copper probe which sits in the pilot light, it opens, and holds open, the main gas valve.
    unlikely (but possible) its this as the pilot flame stays lit

    2) blocked jet in the burner.

    3) if the boiler has an electronic circuit board, that may be faulty.

    none of these are really repairable as the thermocouple is sealed for life, unless you understand electronics you cant repair the circuit board and the hole in the jet may be scored or enlarged if you poke something through to clean it....but very careful probing with very thin soft wire may clean it enough to prove that is the fault before buying a new jet.
     
  3. nsr500rossi

    nsr500rossi Read Only Funster

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    Hi Thanks for you reply

    If it's the therm coupler, then it is not opening the main gas ..is that right? you say not likely as the pilot stays lit, well i thought if the coupler packs up it does not effect the pilot ..am i wrong

    I don't think the boiler has a circuit board, it is very old.

    Blocked jet, where could it be blocked? can i get to it

    Thanks

    Mike
     
  4. pappajohn

    pappajohn Funster Life Member

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    hi again Mike,

    the thermo couple does hold the gas valve open which also controls the pilot light.

    I'm assuming you need to light the boiler manually with an ignitor button and not just press a switch so, when you press the igniter button to light the pilot, the pilot flame will heat the thermo and hold the valve open, this is why you need to hold the igniter button in for a while...let it go too soon and the pilot will go out.

    i did wonder, because of age, if it would have an electronic circuit board.

    without seeing the boiler i couldn't say just where the jet will be but it will be accessible wherever it is.

    sorry, not much help really.
     
  5. nsr500rossi

    nsr500rossi Read Only Funster

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    Ok so it is not the thermo coupler as the pilot lights easily and stays lit.

    Trying to work out how the diaphragm works, i have dismantled the water section, i can turn the hot water adjuster dial, the rod connected to it turns as it should, is this just opening a valve inside?

    there is another metal rod that i can push in and out, it is spring loaded, should this go up and down when the dial is turned, it does not at the moment..

    Bit lost now.

    if the jet is blocked, will that be inside the main gas valve

    thanks

    Mike
     
  6. Terry

    Terry Funster

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  7. nsr500rossi

    nsr500rossi Read Only Funster

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  8. nsr500rossi

    nsr500rossi Read Only Funster

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    Oh my, clearly i am pretty stupid...

    I was not turning the dial back to the gas on position, so click, light, dial springs back and thats how i was leaving it, did not see the little gas flame on the dial (it was slightly out of view from the side i was looking from)

    I now have lovely hot water ...

    Thanks to all who help, i really appreciate it, at least i now have a better understanding of how the boiler works

    Mike
     
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