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5-year old Weil startup CLUNKing

DC Member Posts: 2
My 5-year old Weil-Mclain boiler is making
a loud clunk-clunk-clunk-clunk noise when it
first fires. Maybe 15 clunks. What could be
causing this?



  • doug_10
    doug_10 Member Posts: 102
    Could be anything

    Gas or oil? Steam or hot-water? If it's hot water - what kind of circulator, what's the pressure, how many zones, are there zone valves, what kind, etc, etc. Need lots of details, might be best to call in an expert to check it out.
  • DC
    DC Member Posts: 2

    Thank you for the response. I would like to hire an
    expert... and will have someone look at it, but so far
    the persons working on my boiler, including the installer,
    have not been satisfactory. If you know an expert in
    my area - about 40 minutes north of Columbus OH, please
    recommend. I do like to have an idea what might be wrong, so I can ask questions and be informed when whoever I try next comes.

    This is a hot water baseboard heat system, 3 zone valves.
    The circulator pump is the one that comes with the boiler
    I believe.

    History of the system follows... in case it matters...

    I have had several problems with the system
    in the past - first was that the installer could
    not get all the air out of the system,
    installer just told me to bleed regularly. I
    finally had a couple of automatic air vents installed
    including a 'supervent?' and the air problem went away.
    The supervent is on the pipe coming out of the boiler.
    There was (still is) originally a single air scoop on the pipe coming into the boiler, before the pump.

    Last year the pressure relief valve started leaking.
    I replaced it myself, the new one leaked as well.
    Had 2 companies come and investigate. I had read that
    the expansion tank (bladder tank) being bad could cause this, and indeed it read no pressure. Neither company
    looked at the bladder tank - until I suggested it, and
    even then they did not think that could be the problem - they said the pressure gauge is reading under 25 lbs and the
    relief valve is leaking, it must be a bad valve. I
    replaced the bladder tank myself and the leaking stopped.
    [I paid each $75 for their diagnosis]

    Now, one thing I have read is that if air is in the
    system, the cast iron might corrode, and a 'percolating'
    noise might indicate this, and it might need 'deliming'.
    So that is my only hint at the moment. We will see what
    the next person says.

    Thanks for any advice.
  • Dan M
    Dan M Member Posts: 50

    I had a 6 year old Weil Mclain "Gold" GV5 die in my house 2 years ago. It kept shuting down. Three different Pro's tried to debug the unit at my expense before it was declared dead. The fatality was a resuilt of a less than perfect install ( Professional) and possible problem with the boiler (Mixing valve). Weil Mclain replaced the boiler with their redesigned model with internal pumps for better water mixing.
    I ran into the same problem in my area ( northwest ill )with contractors that were unfamiliar with the intricate workings of the Weil-Mclain which resulted in a even more nerve racking installation the second time around . I had a lot of circulation trouble with the new boiler but was eventually able to resolve it. As you may have found out Weil Mclain will not talk to a home owner ( "liability" or what ever). I even asked them for advice on who in my area that they had worked with and they remained unhelpful. You get caught between the wronge contractor and a company that is scared of you. Its a hopeless feeling. I have a lot of respect for the people on this site and their knowledge I read it every day because it is interesting and full of info. Reading others postings and asking questions as well as buying a couple of Dan'S books ("Pumping Away") got me througth the wilderness The Pro's on this sight indirectly fixed my boiler with out knowing it. To do it over I would select a brand of boiler that was matched to the knowlege base in my area.
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