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munchkin contender heat exchanger problems and thoughts.

_HeaterDude_ Member Posts: 15

I was wondering what your thoughts are on the contender boiler.

We have never installed any because of being concerned with the composite construction of the heat exchanger.

I have encountered a 3 of them installed by other contractors so far.

One was fine.

One I was called out to inspect and see why it was leaking and give recommendations to fix it....it was installed completely wrong, without going on forever it had no reducing valve and had 80psi water and blew the seal on the plastic header.

The third one was piped fine, pressure was fine, but the plastic header was cracked and was leaking.

I was shown the new NTI boiler that uses the same heat exchanger recently and am still concerned with it being plastic.

Any input would be great.

Thank you


  • Gordy
    Gordy Member Posts: 9,546

    Frankly I would choose a boiler with a SS HX, and a fire tube Designed HX. Can't really say much about the composite design. The proof would be in what you have witnessed, taken with if it was installed correctly is the difference.
  • hot_rod
    hot_rod Member Posts: 21,866
    The HX

    inside the composite shell is still stainless.

    The Cadet also uses a composite case. I've run a Contender at my shop since they were introduced and not seen a problem.

    You will be seeing a lot more composites in our industry, manifolds, mixing blocks, air and dirt removers are already on the market.

    Composites come out of the "mold" ready to go. No need for multiple machine process like brass casting or forgings. Also the raw material cost is more stable.

    Composite pex fittings are on the banner ad next to this post :)

    Even exhaust manifolds for engines are being squeezed from composites, and many heat exchangers, including some solar absorbers.

    Installation care is one key. Avoid any stress on the connections, and allow thermal expansion room.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • _HeaterDude_
    _HeaterDude_ Member Posts: 15

    I have been noticing all the influx of composite components, and have yet to install them myself. Have replaced a number of auto air vents that failed, manifolds, and small parts in some boilers & thankless water heaters. Doesn't instill confidence in the longevity is such components, but that might be the point...cheap and disposable over quality......
  • SWEI
    SWEI Member Posts: 7,356
    most composites

    laugh at common water challenges like hardness, pH, oxygen, and chlorides.  They're also far less subject to the whims of commodity markets.  Time will tell, just like it did with polymer piping systems.  We have PEX and PP-R, but we also had to get through PB, Entran II, and Kitec.
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