Central gas with new ducts or ductless heat pump.

January 21, 2013 1:28 PM

Our home in Seattle contains a dozen or so electric heaters. We would like to get rid of these and upgrade to something more efficient/attractive/economical. It seems our two options are 1) Central gas heating or 2) ductless heat pump. To make gas heating work, we would have to install ducts. Does anyone have any experience with adding ducts to a ductless house? One possibility that has been suggested is to put the ducts on the outside of one side of the house. This would probably work in our case since all of the large rooms in our house share a common wall. What are your thoughts/experiences with installing either gas heating with new ducts or ductless heat pump heating? I'm assuming that central gas would work just fine in a Seattle winter but I'm not sure if a ductless heat pump system would be adequate in the winter ( considering that our hope is to replace - not just augment - the existing system ).
posted by metadave to Home & Garden (14 answers total)

We are going to need a description of the house. Attic, basement, crawlspaces, etcetera.
posted by Mr. Yuck at 1:50 PM on January 21, 2013

You might want to check with your power company to see if they will do an environmental audit to see if you are insulated properly.
posted by iamabot at 1:51 PM on January 21, 2013

The cost of installing duct work is going to depend on the design/layout/construction of the house. I would really recommend that you bring in a contractor to give you a price on the work necessary to do so.

A cheaper option might be baseboard/hotwater heat, have you considered that?
posted by HuronBob at 1:53 PM on January 21, 2013

Ductwork leaks heat, which inside the house is beneficial but in your case means you will be heating the outside (especially as the exposed ductwork will already be so cold).
posted by saucysault at 2:06 PM on January 21, 2013 [1 favorite]

Personally, I'd go for baseboard hot water. I had it in a previous condo and preferred it to the forced-air system in my current place.
posted by aramaic at 2:19 PM on January 21, 2013 [2 favorites]

External ducts will make your house really ugly, and seriously detract from the resale value.
posted by Chocolate Pickle at 2:24 PM on January 21, 2013

I had duct work added on in an attic for central heat, it worked well as far as heating the house.

You'll probably get more useful answers to this if you can tell us more about the house, so far all you've indicated is that it has an exterior wall and some rooms.
posted by yohko at 2:49 PM on January 21, 2013

I recently did some reading about this, because I also have a house in the PNW with electric baseboard heat. I found a lot of information about how amazing ductless heat pumps are, but this article really gave me pause. It seems like the ductless heat pump would be great for heating up open-plan areas of your house, but it also made it clear that the heat pump would not really act as a replacement for the electric baseboards - you would still end up using them if you have isolated rooms, like I do. Also, they quoted the average savings for this area as $280/year. If you only need 1 heat pump, that's still a 14-year payback time. It's probably highly dependent on the layout of your house - my house has very few open areas and many small, isolated rooms, which is why I think I'm better off staying with the baseboards, even though I hate them. (There is evidence that my house had hot water radiators at some point in the past, and if I knew which owner took them out and put in the electric baseboards I would cheerfully throttle them.)

That being said, in Seattle I think you buy electricity from Puget Sound Energy, and they have a rebate right now for ductless heat pumps that you might qualify for here.
posted by periscope at 3:19 PM on January 21, 2013

Our ducts are in the "attic", i.e. the unfinished space between the roof and ceiling. They live there together with spiders and insulation bales. Seems to work well.
posted by lollusc at 4:17 PM on January 21, 2013

I agree that an energy audit is the place to start. Depending on your house, electric baseboard heaters may prove to be your most efficient option for your situation and the money you would spend on a new system. In any case, upgrading is not super helpful unless your envelope is well sealed. The Energy Efficiency Pyramid is a good way to approach this sort of thing: you start at the bottom with improvements that generate the most bang for the buck, and work your way up.

Another article from the same blog, “Musings of An Energy Nerd” (which I highly recommend), points out that ducts installed in non-conditioned spaces waste tremendous amounts of energy.
posted by oneirodynia at 4:48 PM on January 21, 2013 [1 favorite]

If you're in Seattle proper, your utility is Seattle City Light. Here's their $1500 rebate program for ductless heat pumps.
posted by ShooBoo at 4:49 PM on January 21, 2013

Response by poster: Thanks for all the great feedback so far!



We are going to need a description of the house. Attic, basement, crawlspaces, etcetera.

The house is narrow with a flat roof ( no attic ) and sits on a concrete slab ( no basement or crawlspace ). It has three levels which are all basically rectangular.


You might want to check with your power company to see if they will do an environmental audit to see if you are insulated properly.

We did that recently and were told that our insulation is "adequate".


The cost of installing duct work is going to depend on the design/layout/construction of the house. I would really recommend that you bring in a contractor to give you a price on the work necessary to do so.

We are in the process of scheduling estimates. This ask.metafilter.com question complements that process.


A cheaper option might be baseboard/hotwater heat, have you considered that?

Thanks for the suggestion - we had not been aware of that option. I'll add it to the list of possibilities.


Ductwork leaks heat, which inside the house is beneficial but in your case means you will be heating the outside (especially as the exposed ductwork will already be so cold).

After reading these responses it seems clear that outdoor ductwork is not a good option so we're crossing it off the list. Central gas in general is looking less viable.


I recently did some reading about this, because I also have a house in the PNW with electric baseboard heat. I found a lot of information about how amazing ductless heat pumps are, but this article really gave me pause. It seems like the ductless heat pump would be great for heating up open-plan areas of your house, but it also made it clear that the heat pump would not really act as a replacement for the electric baseboards - you would still end up using them if you have isolated rooms, like I do. Also, they quoted the average savings for this area as $280/year. If you only need 1 heat pump, that's still a 14-year payback time. It's probably highly dependent on the layout of your house - my house has very few open areas and many small, isolated rooms, which is why I think I'm better off staying with the baseboards, even though I hate them. (There is evidence that my house had hot water radiators at some point in the past, and if I knew which owner took them out and put in the electric baseboards I would cheerfully throttle them.)

That being said, in Seattle I think you buy electricity from Puget Sound Energy, and they have a rebate right now for ductless heat pumps that you might qualify for here.

It sounds like our house might be better suited to the ductless heat pump than yours. Articles like the one your posted are one of the reasons that I'm asking this question. I keep on getting the impression that ductless heat pumps are *almost* enough to heat the house but we will still need the electric space heaters some of the time. I'll talk to the contractors about this when I get quotes. We do qualify for the rebate and we are taking that into consideration.


Our ducts are in the "attic", i.e. the unfinished space between the roof and ceiling. They live there together with spiders and insulation bales. Seems to work well.

Thank you. Unfortunately, that's not an option for us.


I agree that an energy audit is the place to start. Depending on your house, electric baseboard heaters may prove to be your most efficient option for your situation and the money you would spend on a new system. In any case, upgrading is not super helpful unless your envelope is well sealed. The Energy Efficiency Pyramid is a good way to approach this sort of thing: you start at the bottom with improvements that generate the most bang for the buck, and work your way up.

Another article from the same blog, “Musings of An Energy Nerd” (which I highly recommend), points out that ducts installed in non-conditioned spaces waste tremendous amounts of energy.

Thanks. As I mentioned above we did have an audit done. The feedback from the audit was basically that our windows needed to better sealed but other than that there are no more easy improvements to be made to our house. I'll check out both of those links.
posted by metadave at 5:02 PM on January 21, 2013

Have you considered the small split-unit heat pumps that are now available? As I recall there are a few models that allow for multiple blower units connected to the same outside condenser unit.

And concerning your energy audit, did it include a blower-door test to determine the number of air exchanges you're getting? Poor insulation = not good. Lots of air exchange = REALLY BAD.
posted by sandpine at 8:59 PM on January 21, 2013

Good god I love my ductless heat pump. I put them in about a year ago, also living in Seattle. I could not do indoor ducts due to the already-low ceiling in my basement...plus they're just ugly in my opinion.

I have had many forms of electric and fuel-based heat and these are the best. I have a futuristic remote with which I can control everything, including setting timing for the heaters to be on or off, plus a dehumidifier and air conditioning.

My electric bills barely went up when I installed the pumps. Our electricity in Seattle is pretty cheap already. These pumps are very efficient. I used Evergreen Heating for my install. They came out and gave me an estimate free of cost and were incredibly polite, quick and so clean I couldn't tell they had put holes in the wall. Feel free to send me a PM if you'd like to hear any more or even see them in action. I love these things!
posted by nursegracer at 8:47 AM on January 22, 2013