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Munchkins and High Temperature Systems

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I'm convinced that Munchkins that serve radiators or underfloor radiant bare tubing at 150-180F temperatures last longer because they don't develop condensate which would eat away at the HX's.

The only drawback is that they seem to need replacement blowers motors quite often as the heat in the cabinet leads to degradation. It just occurred to me that we should leave the covers off these units, but there may be an issue with make-up air.

I have a few customers with high temperature systems with Munchkins 18-20 years old. The most recent one just went through his fifth blower motor, but the HX looks pristine and had very few coffee grounds after 3 years.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab
kcopp

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  • JUGHNE
    JUGHNE Member Posts: 11,109
    edited March 2022
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    Possibly, in Nov of 21, I just opened a 199k Munchkin from 2006 for it's first cleaning, that was confirmed by the installer BTY.

    It has fin tube convector cabinets with a little BB.

    I was expecting a real mess but actually very clean, even the rear target wall was in great shape.

    And also it is NOT piped primary/secondary with only an Astro 50 pump.

    (The 2006 I&O book did show this approved piping....not later editions did so)

    It was short cycling between 160 and 180. TD of 10 degrees at 50% fire.

    The service call was for F-9 flame failure.

    The original (2006) flame sensor and ignitor were changed to correct the F-9.

    It is on it's second blower motor.


    I now own it and may have cursed it.
  • kcopp
    kcopp Member Posts: 4,448
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    I certainly have seen some still working after 15 years. They tend to be the natural gas ones. As with anything water quality can be an issue.
  • hot_rod
    hot_rod Member Posts: 22,480
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    I'm convinced that Munchkins that serve radiators or underfloor radiant bare tubing at 150-180F temperatures last longer because they don't develop condensate which would eat away at the HX's.

    The only drawback is that they seem to need replacement blowers motors quite often as the heat in the cabinet leads to degradation. It just occurred to me that we should leave the covers off these units, but there may be an issue with make-up air.

    I have a few customers with high temperature systems with Munchkins 18-20 years old. The most recent one just went through his fifth blower motor, but the HX looks pristine and had very few coffee grounds after 3 years.

    Are they vented with standard PVC? I've seen the PVC go yellow on those high temperature systems. The Ultras were notorious for discolored PVC when used at high temperatures.

    Good observation about lack of condensate.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,840
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    I well remember many discussions about condensate when the first high efficiency stuff hit the market. They basically told us we could drink it. Neutralizers, eaten up copper tubing came later with field experience.

    When did the first high efficiency stuff come out?

    I know a job with a 32 year old Comfortmaker high efficiency furnace that still runs fine (yes the hx is ok)

    Were the Pulse furnace first??
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,106
    edited March 2022
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    Were the Pulse furnace first??
    Hydrotherm Pulse, then Glowcore.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab