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Munchkin - failed HX

Over the years, we must have installed over a hundred Munchkins and I still service them for my customers. Yesterday, I visited a job where we installed a Munchkin for radiant heat in 2003 and had cleaned the boiler 3 years ago. The customer told me that the pressure was at zero and she couldn't fill it and make the pressure hold. Often, it's a stuck open relief valve and I brought one with me, but no, I could hear water spraying in the combustion chamber and flowing out the drain.

That's a first for me, but the techie at HTP wasn't phased. "Just get them a new boiler".
Often wrong, never in doubt.


  • heatpro02920heatpro02920 Member Posts: 991

    I have seen my share of bad HX's in munchkins, I think they are 12 yr warranties?

    I replaced one that was 8 years old a couple years back, I remember it well because it was in a closet that you could only fit your arms in to work, but who ever installed it was smart enough to put circulator flanges on every connection, plus the unions on the boiler, so I literally just unscrewed 4 circ flanges {there was even a brass one on the water feed}, unscrewed the unions and pulled all the piping out of the closet, the circulators even had plugs on them... Then unscrewed the expansion tank that was sitting on top of the boiler and gas line which also had 2 unions so you could take out a section and clear the boiler, and the boiler was ready to come out..

    But here is the best part... wait for it.... It was on wheels!!!! No BS we rolled it rite out, of the closet!!!! Not sure if there is a code against that lol, but they installed wheels, I asked who did the work and they had bought the house with the boiler in it, its not the first time I seen cric flanges used as unions but definitely the first time I seen wheels on a boiler... I put the wheels back on the new unit and installed it the same way... Needless to say it was a fast install....

    Another odd thing about the install, first time I ever seen a temp gauge in a flue pipe {plastic}... I repiped the flue and did not add the gauge back in....

    But anyway thats enough about my unit, Looks like you have a munchkin swap out in your future, is it under warranty, if not are the customers going with the same unit? I would test the water, and recommend one of them new chem injection systems with the filters built in, I forget the name of them, it looks like a huge funnel and they make the cans to plug into them for filtering, lubrications, antifrz, ect..
  • Mark EathertonMark Eatherton Member Posts: 5,584

    I think Heatpro is referring to the Sorbox filtration treatment system that has been bantied about here on the Wall recently. DO a word search on SOrbox and JohnNY and it should pop up.

    I for one would be interested in seeing how and or why the HXer failed. I had a pioneer in the hydronic ModCon field (Hi Pete) tell many many years ago that the helical design of HXer, if applied in an older cast iron or ferrous based system would get a compound called magnetite that would accumulate in the HXer, and cause improper cooling (over heating) and early failure. I consider him a pioneer because he actually imported the first aluminum block condensing boiler to the US market (non condensing, French design)

    If you have the time and gumption Alan, you should cut the HXer apart and see how it failed? Blueing would indicate inadequate cooling and subsequent failure…

    Having personally cut a HXer out of the blow molded jacket before (using it on my stump stove woody biomass converter) it is NOT easy to get it out of the plastic, but once that's done, I suspect if you clip a couple of bands, the HXer should come apart fairly easy. Think Sawzall with 4" wood blades :-)

    Take lots of pictures.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Charlie from wmassCharlie from wmass Member Posts: 3,925
    I have only had one leaking Munchkin

    I did not install the boiler but was called when it was leaking. The leak was one of the factory installed nipples sheared off at the tapping into the heat exchanger. It leaked into the heat exchanger drain and was running out mostly to the condensate drain. The owner was not interested in their warrantee and opted for a Veissman.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • hot rodhot rod Member Posts: 7,094
    i agree with ME

    it would be interesting to see if the failure was from the inside, due to water quality. Or possibly a flow issue that may have caused overheating and damage from the outside.

    Gas quality and burner adjustment could also lead to pre-mature failure.

    Problem is, it is often more expensive to have labs qualify the failure then just replacing the HX, or boiler.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Warranty

    It's an 11 year old boiler and the HX is guaranteed for 12 years. HTP offered the owners 50% off on a Contender, but will also talk to them about another manufacturer. I'm interested to find out where it leaked, but won't be able to do any destructive analysis if we have to return the boiler for warranty.

    Mark: Yes, I remember Pete Caruso and buying a dozen of the French Monitor boilers from him 15 years ago. I believe all are still running.
    Often wrong, never in doubt.
  • Mark EathertonMark Eatherton Member Posts: 5,584
    I am betting...

    If you ask the factory for permission to send back just the serial number plate as opposed to the whole carcass, they will let you keep the body... They aren't collecting them or anything :-)

    Talk to Brian French in engineering.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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