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Intertherm M1 Furnace

1.3 of 5 stars 7 reviews | #2 of 2 Furnaces
Updated: Sep 24, 2018 | Read more about Intertherm Furnaces | M1 Warranty

Overview of M1

The Intertherm M1is an 80% AFUE furnace for use in manufactured housing. It has an insulated cabinet which ensures minimum heat loss and quiet operation, and the cabinet finish is coated to protect against rust and corrosion. The M1 features an aluminized steel drum-style heat exchanger, a multi-speed direct drive blower and a sealed combustion system. The M1 is designed for all sizes of manufactured and modular homes, and all models are AC ready.

Consumer Reviews of the M1

1.3 1.3 of 5 stars 7 reviews
  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
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1 of 5 stars Cottage Grove, MN
Date created: 2018-09-24


I replaced my furnace 4 years ago. Since then, I have had to have it repaired 3 times at a cost of about $750. One time was the igniter, one time the exhaust motor, and one time the gas control valve. I would not recommend this furnace to anyone. All you people that are satisfied with yours, just wait until you replace it and see how much trouble you have. The new ones just don't last.

1 of 5 stars Moonachie, NJ
Date created: 2015-08-19

Worst furnace ever!

Number 1 problem, the circuit board mounted on the fire box causes furnace to malfunction; easily fixed by putting insulation behind the board. Number 2, when you have to apologize to your neighbors because your furnace is making too much noise, you're just not going to get much sleep at night. Avoid buying this piece of junk.

1 of 5 stars Boulder, CO
Date created: 2014-12-03

Total POS!

This unit came with my new home and when it was 1 month out of warranty (13 months old - can you believe that?) it required an $804 booster motor and pressure switch. This company's 1-year warranty sucks, it pretty much says how much faith they have in their product, and their customer service sucks even more! The service guy that came to work on it also said that the main blower motor isn't long for this world either, based on its extremely noisy operation. If you have a choice, absolutely do not buy this piece of crap product! I know that once this unit becomes too expensive to keep running, I'll be very careful to never buy another product from Intertherm - ever!

1 of 5 stars Carleton Place, ON, Canada
Date created: 2014-11-01

Replaced switch

This furnace was installed in our mobile home upon agreement to purchase the home April 16, 2012. We have had problems with the switch #632453r ever since the first winter season of 2012. To date, we have replaced this switch for the fourth time; once in 2012, twice in 2013 and today, November 1, 2014. There is a definite problem with this switch and Nordyne, the manufacturer of this furnace, which is Intertherm, has to come up with a solution. The furnace will not operate once this switch goes. I have no alternative within my space to use any other kind of furnace. My choices are very limited. I called Nordyne within the first year of having this furnace and they told me it was not under warranty. The documentation says one year parts and labor. I do not recommend this furnace, simply because of this faulty switch that keeps breaking or wearing out.

1 of 5 stars Ashville, Al.
Date created: 2014-08-18


This unit is so loud the neighbors can hear it when it's running. We installed a door down the hall where the unit is located, to try and muffle the noise. Several months later we had a repairman come out and service the unit because the vents stopped blowing cold air. The serviceman told us we could not close the door we installed because air cannot circulate through our house, and it is working harder to cool our house. So we are still living with the loud noise it makes. I would not have another one of these units if they were giving them away.

1 of 5 stars Mantua, Oh
Date created: 2011-10-14

Not a Happy Camper!

I needed a new furnace in December of 2009. The company I used at the time replaced the old one with the same brand Intertherm M1MB-090*. I live in a mobile home, which only leaves me w/ a couple of choices. Ever since it was installed I have said it did not heat as well as the old one. They checked the air flow & temperature & said it was up to par. It still does not heat as well no matter what they say. Now the bearings in the draft inducer motor are "Defective", that's what the repair man wrote. They said it would be $455 to fix. The part is defective for crying out loud. The furnace only has a 1 year warranty. I think this crap about having to buy extended warranties is for the birds. Make a good product, stand behind it, & quit gouging the little people!!!

3 of 5 stars FairPlay, MO
Date created: 2011-03-24

Outdated and inefficient.

I have owned my furnace for eleven years now. It is an eighty percent propane furnace that has an output of forty-five thousand BTU's. I like it for the warmer heat that I feel when it comes on and for when the power is out, my small generator will run it with no problem as it uses gas for the source. I do not like the cost of feeding this furnace propane with the rising cost of fuel. I say it is outdated and inefficient in my title because there are newer and better gas furnace products on the market that can save me a larger chunk of change both in heating my home and in operating cost. I am neutral in my standing on it as I have only had to replace the thermocouple since owning it which makes it reliable but, I feel it does not adequately heat my home and is costly to use. I may buy and recommend the same brand only if I could get a ninety percent furnace instead by that manufacturer.

Other M1 Reviews

Based on the very few comments about the unit on HVAC forums, the M1 is regarded as a good furnace. A reviewer on had an issue with his M1, but it turned out that the problem was caused by the thermostat and not the furnace.

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Intertherm M1 Model Numbers

The M1 is available in different models which vary in efficiency and capacity.

Model Number AFUE BTUs per Hour
M1MB-056* 80 56,000

M1 Warranty

The Intertherm M1 Furnace is covered by a 10-year heat exchanger warranty and a 1-year parts, labor and mileage warranty. A Contractors' Preferred Protection Plan is available to extend the parts and labor warranty to 5 or 10 years.

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