HTP Munchkin Boiler Overview

The Heat Transfer Products Munchkin is a discontinued fully modulating gas boiler with an efficiency of 90% AFUE. It featured a stainless steel heat exchanger for optimal heat transfer and resistance to corrosion, and its compact, lightweight design provided greater installation flexibility. An Inconel NIT burner and spark ignition assured reliable operation, while a self-diagnostic microprocessor control monitored the system and made servicing easier.

Later versions of the Munchkin boiler include the Munchkin R1 (Revision 1), featuring a digital display and upgraded burners, and the Munchkin R2 (Revision 2), which differed from previous units because of its wiring and metal latches.

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Consumer Reviews of HTP Munchkin


  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
  • #4 of 11 HTP Munchkin Boilers
  • 25% of customers recommended

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HTP Munchkin Boiler Reviews

Showing 1-5 of 28 reviews

"16 Years"

5.0 rating
Very Satisfied

Had this installed in 2003 to heat 5000 sf including domestic water. It had a few issues that I was able to figure out (new board, fan, electrode a few times). My brother has a smaller house and uses 2 regular Water heaters and 2 he furnaces. He keeps parts of the house unheated and still pays more than me in my toasty house (live in the same town). When properly installed and maintained, the Munchkin is hard to beat.

Ramy Mughannam

Petaluma, CA

"Lived 11 years"

2.0 rating
Somewhat Unsatisfied

Paid top dollar to learn it broke all the time because it was "sensitive" !? Constant breakdowns, three gas valves, backfiring so loud would shake the whole house and scare neighbors. Spent 260$ to find out was dead as the last laugh. Bought a Bosch Greenstar, put it in today. Combi unit so no indirect water heater anymore either

Citizen of New York state


"Quite Happy with Mine"

5.0 rating
Very Satisfied

My Munchkin 80m was installed in 2002 and has pretty much worked extremely well ever since. In about 2014 the blower was replaced, but other than that I have had no problems. I get a maintenance visit for cleaning about every 3-5 years. I would definitely consider buying another HTP product based on my experience with this Munchkin.

Joe Stevens


"Munchkin condensing boiler"

1.0 rating
Very Unsatisfied

An over-engineered piece of junk. Don't ever buy one. At least once a week at the HVAC company I worked, munchkin would send us service updates ,'here's how to fix this problem' next week ' here's how to fix this problem. Eliminate your problems by not buying one!!

Fred Vogt

"HTP owes me some money"

1.0 rating
Very Unsatisfied

I purchased a Munchkin boiler from a respected contractor in 2007. Last year I started having problems with it. Imagine my surprise when I was told that it's time to replace my 11 year old boiler! Apparently, there have been 'problems with it.' I was told 'that heat exchanger could go anytime.' Who sells a boiler that has such a short life span? HTP, your response and warranty is a joke. As far as I'm concerned, you have stolen from me.

Mike A.

Upstate New York

Other Munchkin Reviews

Many of the comments regarding problems with the Munchkin have to do with them not firing properly. A professional on said that he’d done many service calls on the units and almost all of the problems were due to the gas/air mix not being set right.

Question and Answer


What does a Munchin fault code F-02 mean?


According to page 63 of the Munchkin Gas Fired Boiler manual:

Fault Code F03 description: “Interrupted or Shorted Return (Inlet) Thermister.”

To fix/remedy the problem:

  • Check the electrical connection to the thermister on the outlet manifold. Verify 5 VDC by checking in Molex connector. Verify thermister values by referencing chart in this manual.
  • Replace thermister if necessary.

Munchkin Warranty

The warranty for the Heat Transfer Products Munchkin boiler is comprised of the following:

  • Complete 1-year warranty on defective parts
  • Limited 3-year blower motor warranty
  • 12-year heat exchanger warranty, pro-rated after the 7th year

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