HTP Honeywell Boilers | FurnaceCompare®

HTP Honeywell Boiler Overview

The Munchkin Honeywell series gas boiler was manufactured by the company Heat Transfer Products (HTP) until 2002. Munchkin boilers occupy a small amount of wall or floor space, and are billed by HTP as “the original high efficiency low mass boiler produced in the United States.” Munchkin Honeywell series boilers were commercial boilers and carried the following model numbers: T50M, T80M, 80M, 140M, 199M and 399M.

The 399M model Munchkin boiler boasts a 93-percent AFUE rating. The unit is constructed of stainless steel, and is reportedly so lightweight it can be installed by one professional. The Munchkin boiler digitally monitors its own operation for efficiency purposes. Honeywell is an original equipment manufacturer for Munchkin boilers, producing such parts as gas valves and heating controls.

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Consumer Reviews of HTP Honeywell


  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
  • #6 of 12 HTP Boiler
  • 8% of customers recommended

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HTP Honeywell Boiler Reviews

Showing 1-5 of 25 reviews

"Buyer Beware"

1.0 rating
Very Unsatisfied

I have radiant heat serviced by a Munchkin gas boiler. I have had it maintained faithfully, but last week, during a routine maintenance visit, the service person found a hole in the boiler. I had to have this fairly new unit replaced. The company did provide a new unit, as specified in the warranty, but I was left with a $2000 labor cost for reinstalling the unit. I contacted the company and they hid behind their legal warning that all labor costs must be born by the customer. I am not satisfied with the policy, and I am no longer happy with the craftsmanship of the Munchkin machine or the HTProducts service. I am here to say, "Buyer Beware!" I am.

Jerry A. Rice

New Paltz, NY

"Down But Not Out"

3.0 rating

My Munchkin t80m has worked error free for 6 years. In Dec it start to show signs of problems. It started to occasionly pump warm water(not hot) and then clear up. It has had 3 f09's since then and cleared up on it's own. Monday May 6 it f09'd and shut down and won't heat water. I use the boiler for hat water and to heat the basement floor. I have a hi eff forced air furnace because we have winter's of -20 or more on a regular basis. I have read all the posts here and hope I have better luck with my repairs and maintenance. My situation is this. When I took possesion of my house the contractor told me not to touch the system and if it needed work to call the plumber. What a ditz. I did what he said and never did any maintenance or cleaning.(after reading here I think Im the ditz) So after 6 years here is what I have found so far. I inspected the install and have a few concerns. The boiler unit is wall mounted 5 ft off the floor. It does not look like it is tilted at all. I will put some blocking between the wall and the unit to get the tilt. How far out should I block it. 1in? 2In? I found the vacume relief valve was brittle and broken and leaking on the wall and floor. The stain is rust colored. I removed it and there was some condensate water but no alot. I took the cover off and the control display board is mounted inside the unit?? How can a person see an error code if it's in there. I want to mount outside the unit. There is a bit of white crystaline around the exhaust hose. The outside vents are mounted 12 to 16 indh's apart and level with each other. I removed the 2 probes and cleaned them up. Tried the reset a couple times and watched in the window and did not see anything. There was a white/grey coating on them. I am going to do a complete maintenance service today. I will change the probes and gaskets like is stated in these posts. I will clean up all the parts and hope I am still lucky and don't have much more damage. Any help or suggestions is greatly appreciated. It would seem that the problem with this Munchkin unit is just a lazy/uninformed maintenace guy(me) and maybe some install problems. Now to find the parts. The reason I gave a neutral rating is because I haven't done the work or found the parts yet, but 5 years without problems, go figure, I must have one of the good ones.

Sam H.

Carbon, Alberta

"Overpriced and Unreliable"

1.0 rating
Very Unsatisfied

We have had our htp Munchkin 80m for just over 6 years now. It was very expensive to begin with, and I really was hopeful that the unit would provide many years of trouble free service with high efficiency. The unit is certainly efficient and has reduced our home heating bills considerably. However, the reliability has been awe full and this unit has turned into a very expensive lesson! To make matters worse, Heat transfer Products customer device is lousy and they certainly don't care about customer complaints. We have made several requests directly to htp for assistance, and we just keep getting passed to their distributor. Although the warranty covered us for the first few years, it is now out of warranty and having several service calls per year is getting expensive. To date we have had to replace the gas valve, air intake rubber sleeve, the control board and wiring harness. Still, we have f18 errors all the time and have to manually reset the unit 2 to 3x per week. If I had the money… I'd toss this thing out in a heartbeat and replace it with a simple low efficiency boiler. We are now spending close to $1000 year since the warranty lapsed on service/parts for this thing; which more than negates the savings we have achieved for it's high efficiency. To make matters worse, we also purchased a htp SuperStore indirect water heater. This has been replaced once (under warranty but we were on the hook for labor) as the unit developed a leak. Again, HTP's customer service was deplorable. I am very concentious and try to buy American made products whenever possible. With htp being based in ma, and employing local people to make these products – I find it a very sad state of affairs that htp doesn't seem to have any interest in how their products performs once they are out the factory door! *** Bottom line – stay away from htp and their products. I have learned my lesson the hard way. ***

Nick K

Orleans, MA


3.0 rating

M. Lottermoser–Calgary, Alberta—Good job–You're obviously talented. First: Don't change the post purge on your boiler. When the post purge occurs the boiler loop pump is not running so you are not circulating cold water into the heating system. The hx contains about 1 gallon of water, which is insignificant. It is more important to clear the combustion chamber of acidic moisture and gases. Second: It is always good to wear a dusk mask when handling the ceramic refractories. The washer and nut will compress the ceramic which is not a concern. Just tighten it enough to make sure that the nut is securely threaded on the post. Third: You need to replace the burner gasket and make sure that the burner tube is tightly secured by the four screws. Clean the mating surfaces to remove the old gasket material. Fourth: You do not need to replace the probes if they are in good shape, just clean them well. In earlier post I have said how I do it. When cleaning the hx I always remove the target refractory so as not to damage it. Do not use a brass brush to clean the hx, stainless steel or nylon only. Read these post on cleaning the hx. Fifth: Parts should be available well into the future as many of the parts that you may need are used on the newer models. Try for online parts. They are reasonably priced. If I were to stock parts, they would be–the burner gasket-refractories-water pressure switch–one water temperature sensor (in or out). The failure of the blower, gas valve depends on venting (gas reversion), see earlier posts, especially concentric venting. Lastly, if you live in an area with lighting, get a whole house surge protector and be sure and protect the boiler electronics with a computer grade (4200 joules) surge protector.


"199M – First failure in 7 years"

3.0 rating

199M with ssu-60 indirect water heater, two Heat Controller fan coils, glycol system 30%, concentric venting 8 feet above ground on 2 story wall. From reading all the previous posts, I seem to be extremely fortunate on two fronts. Proper installation and venting. No annual maintenance since it was installed 7 years ago (to my shame). The control card just failed, where the relays clicked on and off continuously in one second intervals. Replaced it with a 926 card but noticed the post purge of over a minute seems to cool the boiler output water by 10 F. from when the burner shuts off. Can the post purge be shortened ??? so as not to waste too much heat. The local distributor doesn't keep spare parts so it was going to take over 5 days to get the control card. Fortunately, the winter has been mild here and I was able to get one online from the US within 3 days. During those three days I cleaned the hx and unplugged the condensate drain. Fortunately the boiler was slightly tilted to the back to the drain so only the bottom third of the rear ceramic target wall was water damaged, dropped from the threaded stud but leaning against the rear boiler wall. The washer and nut was buried in the ceramic material. I replaced the rear ceramic target wall but am worried washer and nut will loosen off again. With annual maintenance, this may not be an issue. The drain was plugged solid with coffee ground type material a couple inches above the trap. It would slowly drip but was able to squeeze and tilt the trap downward where after 15 minutes of working it, the rinse water in the hx finally pushed the material out. Rinsed the hx with fresh water from a small pressure hose and was able to flush out all the solids. (7 years worth). It took a few sessions with CLR and nylon brush to clean the hx. But after two days it looks good as new. I cleaned the dust off the burner, cleaned the flame sense probe and ignitor probe. Noticed the burner gasket was slightly loose and will replace it shortly. Should I replace the probes as well, for peace of mind??? The outside sensor failed 5 years ago and was replaced. So in summary, I am very satisfied that the boiler worked fine without any annual maintenance for 7 years but I am very dissatisfied with lack of spare parts in a timely manner. Therefore, the neutral rating. Since the boiler has been manufacture discontinued in 2011, how long will spare parts be available?? Are any components being used in new boilers?? Any further suggestions on what spare parts I should buy and replace based on the 7 year track record?? What is the failure rate of burners, gas valves and blower motors after 7 years? Any other advice would be greatly appreciated. Thanks for all the previous posts. I will keep this boiler and properly maintain it. I would never have guessed that the installation and maintenance of these condensing boilers would be so critical. But that's progress, where the consumers have more due diligence to shoulder. Hopefully, that doesn't sound too bitter.

M. Lottermoser

Calgary, Alberta

Other Honeywell Reviews

A thread on details a discussion between HVAC professionals regarding Munchkin boilers. One installer comments that for the price and performance, he doesn’t understand why anyone would use any other boiler.

A homeowner writes to the experts on to ask about a loud noise that his Munchkin boiler makes when turned on; the unit was previously quiet in operation. After a technician�s house call, the owner reports that the burner gasket needed replacement, and the unit was again operating quietly. One expert commented that this was a common issue with “those boilers.”

A Munchkin owner asks the forum at for help in locating a qualified installer in rural Illinois. The expert installers suggest calling the company, or looking for someone qualified to install the Peerless Pinnacle, which they say is a similar boiler.

HTP Honeywell Model Numbers

The Honeywell is available in different models which vary in efficiency and capacity.

Model Number AFUE BTUs per Hour
140M 92 140000
199M 92 199000
80M 92 80000

Honeywell Warranty

Munchkin offers a 12-year warranty on the Honeywell series boilers. After the seventh year, the purchaser must pay a percentage of the replacement cost. Labor costs are not covered by the Munchkin warranty. The owner must contact the retailer and provide the original receipt for warranty issues.

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