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new natural gas furnace or mini ductless heat pump?

Posted by twotogo (My Page) on
Mon, Nov 4, 13 at 17:57

Dh and I recently moved into an eighty something year old house. In 2010 the homeowners we bought the house from did an extensive remodel. They took the house down to the studs, installed new insulation, drywall, new kitchen, new bathroom and also added a half bath. It has new plumbing and electrical but the natural gas furnace is 22 years old. We have had it cleaned and serviced but the guy said it was old and should be replaced. He did say it was in good working order when he left. So, today a guy from the power co. came to do an assessment for energy on the house and he recommended we get a ductless heat pump. What do you all think? Purchase a couple of those units and use the furnace for back up or just replace the natural gas furnace? It is an 1100 sq.ft. house and we live in the PNW. Thanks!


Follow-Up Postings:

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RE: new natural gas furnace or mini ductless heat pump?

I am not in the business, just a homeowner, but if your gas furnace is in "good working order" i have to wonder why a 22 year old oil or gas furnace should be replaced?


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RE: new natural gas furnace or mini ductless heat pump?

That is what my dh said, lol! I think the guy who serviced the furnace was maybe looking to make a sale but I think he was honest in his assessment that the furnace was old and that we may get a few more years out of it. I was just wondering which would be the best replacement, I had not heard much about the ductless heat pump but have since read a little and they are expensive. Not sure what a new gas furnace would be?


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RE: new natural gas furnace or mini ductless heat pump?

Maybe someone could correct me if needed, but an oil furnace or gas furnace can last 40-50 years if properly maintained and serviced.

That certainly has been my experience in a few of my homes.

A/Cs not so much.


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RE: new natural gas furnace or mini ductless heat pump?

What are you paying for natural gas and electricity? In most parts of the country it is cheaper to heat a house with gas then a heat pump at current rates.

Does the power company provide natural gas? If not then I can understand why he is telling you to switch to a heat pump. His opinion is biased. He had you best interests in mind he should have explained the operating cost of each option.

If the furnace is good working order you don't have to rush to replace. I suggest you live in the house for at least one winter to see how it performs. The furnace is probably very over sized given the new insulation. I would recommend replacing it with at 95%+ efficient gas furnace in the future.


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RE: new natural gas furnace or mini ductless heat pump?

20 years doesn't seem that old to me for a gas furnace. The only thing that as really changed is that there are higher efficiency units available now than before. Also multiple stages. However, in the PNW (around the sound), a HP can work just fine since it is rare to get below freezing. And when I used to live there, electricity was cheaper than dirt.

The answer would be based on the relative costs of electricity to gas.


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RE: new natural gas furnace or mini ductless heat pump?

You've just decreased the heat loss of your home by sealing and insulating it. That means that the furnace is probably way over-sized. That would be an indication that it would be good to replace it with a high efficiency model. I too, think that you might as well not be in a hurry. Educate yourselves and then decide what to do.

Where do you live? Where are your ducts. If the ducts are in the attic or otherwise outside of the house envelope, you should have been advised to bring them inside with the remodel.

I like my mini split heat pumps, but I don't need much heat in my climate so the cost of power to do that is not a big factor, but cooling is. On the other hand, an inexpensive furnace is a lot less expensive to buy and replace than an efficient heat pump.


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RE: new natural gas furnace or mini ductless heat pump?

I would keep what you have until it needs to be replaced. At that time you can evaluate the costs for each type but right now, in our area, a natural gas furnace would be alot cheaper.


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RE: new natural gas furnace or mini ductless heat pump?

You are right on the cusp with a 20 yr old gas furnace of when the codes changedand the requirement of all gas equipment was for a minimum of 78% efficiency. That was '93. The question is, is yours one of the newer units or did they put in the older style. If the older, then you may be looking at a 60% efficient unit. Also, those being new designs there were some problems with those "new" units at the time. l guess after 20 yrs we can call your ok;)
Although the previous owners remodeled I would make my mshp/furnace decision almost solely on the condition of the duct system. You need to have it pressure tested for leakage. Google "doeductleakage" to see what I am talking about. If the duct system passes muster then the new furnace is a choice. If it doesn't then it is not. It is not worth spending the money to repair it. I pulled all my ductowrk out and went mshp and Rinnai Energysaver (all Net to the space heating/cooling with no duct or duct losses) As a result, with the elimination of the ductwork I found two good size closets and a large storage area under the stairs and we are very comfortable.


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RE: new natural gas furnace or mini ductless heat pump?

Thanks Jackfre for all the info! I am guessing the furnace was "left behind on the cusp of new efficiency" units back then, in fact, I think the homeowners at the time went "cheap" because their mother lived in the house alone and was going to the nursing home soon.
The duct work, however, is newer from the remodel in 2010. It is a Tempstar(furnace) if that helps. I have never heard of the brand but I am really unfamiliar with natural gas furnaces anyway! Who would do the testing of the duct work? An hvac business? Thanks again for all the info!


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RE: new natural gas furnace or mini ductless heat pump?

The efficiency of the unit should be available from the plate on the furnace.

An energy rater can do duct testing and much more. You should probably get an evaluation of your house. They can identify the low-hanging fruit for energy savings. You can find them at Resnet.us. Utilities and local governments often have programs that help with the cost.

Call more than one and outline what you have and ask about subsidy programs. Hire one based on their responses.


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