The Walden Effect: Farming, simple living, permaculture, and invention.

Energy and cost effective heating and cooling for small spaces

Moving the wood stoveOur new trailer has no furnace and we're not sure if we'll get our wood stove installed and find cured fuel before winter. So now seemed to be the time to get our act in order about a backup heat source.

Mark's first impulse was geothermal since this is the most efficient heating and cooling option currently available. Of course, the downside of geothermal is a hefty price tag. The internet reports that you can install a geothermal system for as little as $7,000, but my on-the-ground research showed up $20,000 as the more-likely lower limit. Given the small size of our space, the current lack of federal tax rebates, and the fact that a considerable amount of our heat will likely be wood in the long term, that price tag seemed unrealistic. So I moved on down the list to heat pumps.

Cost of heating options

The last time I read about the heat-pump option, it didn't seem realistic for our region since heating efficiencies dramatically decline in cold weather. But since then, science has come to the rescue with variable-speed heat pumps that don't start losing their efficiency until 5 degrees Fahrenheit. Plus, if your home is smaller than 1,000 square feet, ductless heat pumps bring efficiency levels nearly to geothermal status for a much lower price tag. For example, this 2,400 BTU unit costs $1,374 (or $947 after Mark's veteran's discount and AEP Ohio's $300 rebate) while boasting operating costs that rival those of a wood stove if you're buying fuel.

I can just hear Mom asking, "But what about the noise?" Ductless heat pumps use circulating refrigerants rather than moving air, so they're much quieter than the less efficient standard heat pumps. All told, they're currently top of our list...but I'd love to hear from anyone who's given them a try and has firsthand information to impart!

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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What about a rocket mass heater? You can build one yourself. There are a few good books out there to help.
Comment by Anonymous Mon Oct 2 07:50:24 2017

Anna, we are in Ontario, Canada and had an air source heat pump installed a few years ago. Our house is small, about 640 square feet. We love it. It starts providing us with heat early in the spring, then into the summer it provides us with cool, dryer air for sleeping during heat waves, then in the autumn it provides us with heat into October, and on milder days right into December.

Our hydro bills are high, but not much higher than they were before the heat pump was installed. Hydro in Ontario, Canada is very, very expensive, so we were pleased that during peak usage, our heat pump costs roughly $50 a month to run, our hydro bills have always cost about $100 a month for bare minimum usage. Here in Ontario most of the bill is delivery, and debt repayment, the actual energy portion of bill is the smallest portion.

When we heated with wood, and purchased hardwood, we spent approximately $1000 per heating season on fuel. Just to give you a basis for comparison.

Comment by Maggie Turner Mon Oct 2 08:46:29 2017
When my double-wide (approx. 1200 square feet) was installed in 1999 in NE TN, they also put in a heat pump. I spent 11 previous years thinking, researching and pondering about heating/cooling etc. any place I may have been moving to. When I installed the house, first of all I found a home that had most of the windows on one side of the house which I oriented to the south. The opposite side of the house has only one large window to the north which I cover with a "quilt" in the winter when it gets really cold (below 32 degrees). Because I oriented the house east/west and the windows capture the heat from about 10 AM to about 3PM, the heat pump doesn't come on during that time period. So far, I've lived here 18 years and have had an average electric cost of approximately $100 per month, including lights, electric stove, computer, etc. What has also helped with the electricity has been insulation that's pretty good. The biggest problem I have found has been cooling the place in the summer, but a new light-colored metal roof over the old black shingle roof (paid for by the insurance company when the wind storms blew most of the shingles away) has reduced the temps during the summer by an average of 10 degrees). So far, I've been very happy with the heat pump/central air. Of course, I'm further south than Ohio or even SW VA, so that needs to be taken into account as well.
Comment by Nayan Mon Oct 2 10:16:57 2017


Heat pumps are often done in combination with horizontal shallow underground collectors. At least here in the Netherlands.

I put some info in this comment on the hybrid heater article.

Those are very effective in winter, because the soil temperature doesn't dip as low as air temperature. Of course, your collector has to be buried below the frost line.

Comment by Roland_Smith Mon Oct 2 13:06:00 2017

We have looked at and considered a ductless heat pump but to be honest we love, love, love our pellet stove. After more than 20 years with wood heat we moved to an all electric home. A home in which I froze for more than a decade because electric heat is expensive! Enter "Harmie"

Due to the homes configuration there was no place to put a conventional wood stove but we had options for easy and cheap installation of a pellet stove as they can vent through a SIDE wall. We heat an 1175 square foot manufactured home in a cold, snowy and wet location in the Foothills of the Oregon Cascades for about $400 a year- a rreally bad year with an extended cold season cost us $600. And we are warm, gloriously warm. The same warmth as a wood stove without the dirt, need for a wood shed and way less effort to put the fuel in each season.

Granted, during power outages we need to run a generator because it takes 165 watts to turn the auger and blower on the stove but that is a "doable" future solar project and you would need a generator to run a ductless heat pump. We consider it a huge plus that we are using what would have been wood waste as our pellets are produced from the waste of a saw mill.

Comment by Elise Mon Oct 2 13:37:01 2017
wow! you got land with a geothermal heat source? what type, hot springs?
Comment by mizz Mon Oct 2 14:02:16 2017
We had two Mitsubishi Electric split ductless systems in our last home to supplement fuel oil -- we really liked them. They are quiet, and performed well (had variable speed compressor, etc). Consider a Mitsubishi system if you can find it -- they are well made.
Comment by Cliff Mon Oct 2 18:03:10 2017
Comment by Theresa Tue Oct 3 13:22:20 2017


On the page you link to I only see 5 °F mentioned in the context of “cooling operations”. I can't find a minimum outside temperature where it can still work as a heater on that page.

According to the spec sheet [PDF] from what seems to be this model, it can heat from an outside temperature of -13 °F, which is quite impressive.

But when it is very cold outside, efficiency will suffer a lot. According to the temperature chart [PDF], when the outside temperature is 5 °F, and the inside temperature is 60 °F, it will yield 19200 Btu/hr. That is approximately 5.6 kW of heat, for an electricity input of 2.39 kW. So the COP is 2.35.

When the outside temperature is 32 °F, is gives 20450 Btu/hr with a power use of 2.22 kW. That is a COP of 2.7. If you want to heat your house to like 70 °F, efficiency drops even further.

So in the winter, I think that you should realistically reckon that you get about twice the electric input power as heating power.

Comment by Roland_Smith Tue Oct 3 16:18:27 2017

We purchased an MSeries 36,000 BTU Dual TriQuad Zone Mini Split Outdoor Condenser Heat pump and four indoor wall mounted units (one 15,000 BTUs for the larger main room; one 12,000 BTUs for the kitchen and eating area; two 6,000 BTUs units, one for each bedroom) two years ago from an on-line company called Total cost was under $5,000 for everything including the piping, insulation, etc. (no shipping charge). My husband installed everything himself but we did get a certified technician to come and verify proper installation so the warranty would be in effect. We have been very pleased with this system. The A/C in summer is amazing--very comfortable no matter how hot and humid. The winter heating is great, but it does feel cooler in the house when the temps start dipping in the low 20's (main room has lots of windows and is not yet well insulated so that no doubt has an affect). Can't give much info on cost comparison to other systems since we heated totally with wood prior to the installation and we did not live here full time previously. The system is very quiet, both the outside unit as well as the inside units. We really like that you can set each room's temperature separately, so for example if one likes to sleep in a cooler room you can set that temperature lower than the rest of the house. If we had it to do over, we would purchase the same unit again.

If you decide to purchase through Home Depot, I would suggest you verify with them prior to the purchase that they will indeed allow the veteran's discount (if that is a large part of your choice). We have recently had issues with Home Depot not allowing discounts on things they had previously honored. We have had no such problem with Lowe's however.

Good luck!

Comment by Norma Wed Oct 4 08:57:45 2017
Is it too early in the year to post a review on your minisplt? What would you do different if you could have a do-over. Still on the fence on whether to buy one for this summer.
Comment by Phillip Sat Feb 10 18:17:48 2018

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