Munchkins and High Temperature Systems

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.

Alan (California Radiant) Forbes said:

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.