Wood stove vs heat pump?

chenopodium · Tar Sands Joined: Jun 07, 2008 Posts: 21

We're planning to build a low energy house with solar panels, solar thermal heating system, very thick walls and good insulation etc.

The question remains is which heating system should we install?

One option is a ground heat pump.

The problem is that it is quite expensive, and requires about 1/4 or so electricity of its heating capacity. If there was no outside power, we would have to run it on our solar panels, which means we would have to spend a huge amount of money buying enough solar panels to run the pump in winter.

The other option is a wood stove.

The advantage is price and that you can run it even if there is no power, also you could use it for cooking in a worst case scenario.

But I worry that we are not the only ones turning to wood, and that there may not be enough wood available to buy! I just read an article that in the US somewhere there is already a wood shortage.

We wouldn't have this problem with a heat pump.

So, would you:
- spend the extra money (which is quite a lot) on a heat pump plus more solar panels to cover it, but then we would have to save on other things such as the amount of land we could buy

- or get a wood stove and hope that we will always have wood available for heating....?

Any other ideas?

Thanks Smile

Quinny · Intermediate Crude Joined: Jul 03, 2008 Posts: 608

I've got a similar problem and I've decided that wood is the way for me, but I think it depends where you are and access to local forest. Buying by the cord will become prohibitively high.

chenopodium · Tar Sands Joined: Jun 07, 2008 Posts: 21

where we live the law won't allow us to just cut down trees. We are at 42 degrees and have a climate similar to say Boston. There are forests nearby, but if people start to cut down trees (illegally) then there won't be much left...

I guess in the worst case there is always the sleeping bag/warm clothes solution (especially in a very well insulated house)?

I like the idea of a renewable source (wood) plus that we could cook with it in the worst case.... (plus that it is a lot cheaper than the whole PV/heat pump/floor heating installation)

I would guess wood would become as expensive as oil?

killJOY · Fission Joined: Feb 21, 2005 Posts: 2510 Location: ^NNE^

No-brainer.

Woodstove, or wood/coal combination.

Less complex, cheaper, easier to maintain.

Wood ashes are good for the garden (but keep them away from potatoes.)

Coal ash is neutral and can be dumped in the woods without harm. (I'm assuming anthracite as fuel, which is hard, high-quality, clean-burning.)

You can cook on a wood/coal stove.

You can heat your water with it.

You can fire it up quickly, on demand, during a cold snap.
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purdum · Tar Sands Joined: Feb 15, 2005 Posts: 34 Location: MI, USA

We were in a similar situation several years ago, when deciding how to replace an ancient oil furnace, and geothermal was the clear choice for us. Your mileage may vary of course, especially if your heating needs are substantially less than ours.

Have you done a complete cost analysis and sizing of the geothermal system yet? You should be able to work backwards from the degree day numbers for your location and estimate the heat loss for your house using software like HVAC-Calc. We designed our geothermal system for 81 million BTU/year, which required a 6-ton unit (cutoffs for smaller units are 73 MBTU for 5 ton and 68 MBTU for 4 ton). If your house is superinsulated, you might get by with an even smaller unit. We had 6500 degree days of heating last season and the heat pump used 9000 kwh of electricity. In our location, with an average of 3 hr/day sun, that's a lot of solar panels (I recall doing a back-of-the-envelope estimate for panels, batteries, inverter etc and coming up with $45K).

You can save some money on the geothermal by designing it to cover 90% of your house's heat loss and rely on auxiliary heating or blankets for the other 10%. For us, when it is below 7 degrees F outside, the house loses heat faster than the heat pump can replace it. But the average winter here (central Michigan) only has 130 hours below that temperature. We figured we could tolerate a bit of a chill for 130 hours rather than spend a few thousand dollars more for the bigger heat pump unit.

As for the wood supply, do you have enough land to maintain your own wood lot? And you may have other options for wood - here you can get a permit and harvest fallen logs and dead wood out of any state land for free. Our neighbors also have good tracts of wooded area and we can barter for firewood. We are installing a wood stove as backup for the heat pump.

Another factor which persuaded me to switch to geothermal is that our utility uses coal and nuclear sources for most of its power rather than natural gas or oil, so our electric rates have gone up very little compared to other parts of the country.

PM me if you want a more complete $$ analysis of our heat pump system.

Blacksmith · Posted: Sun Aug 10, 2008 7:51 am Post subject: Re: Wood stove vs heat pump?

I can't see wood as a problem. There is always scrap wood , broken pallets, scraps from a manufacturer, shorts and cutoffs from a lumber mill, scrap wood from construction sites, and people who want to get rid of branches or trees they have cut down.

As a last resort you can build a Russian stove and burn straw.

I myself get a lot of wood from the burn pile at the local dump, not pretty and have to look out for nails, but it burns.
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dunewalker · Posted: Sun Aug 10, 2008 8:10 am Post subject: Re: Wood stove vs heat pump?

korosten · Tar Sands Joined: Jun 09, 2007 Posts: 53

(deleted)

chenopodium · Tar Sands Joined: Jun 07, 2008 Posts: 21

Thanks for the replies so far!

I guess you're right that there is still scrap wood in some form in the worst case. Could straw also be burned in a wood stove to generate enough heat, or do you need a special (Russian) stove for that? Can you turn a regular stove into a Russian stove?

Our land is pretty small (considered "large" in this area, around 10000 sq feet - it is very expensive here, because we want to live near public transportation), and we could probably plant 3-4 trees or a few more Smile (we still want to have room for as many vegetables/edibles as possible).

Re Georgia: I guess I need to read those threads... I admit I have no real idea why this should be such a problem for us... unless the war spreads and turns into a bigger war... I'd better start reading Smile

The_Virginian · Light Sweet Crude Joined: Jun 19, 2004 Posts: 1528

GET BOTH !

Being prepared, or having ability to switch to wood as a back up is the best assuming you can afford it.
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chenopodium · Tar Sands Joined: Jun 07, 2008 Posts: 21

We "could" get both in theory... but that would mean we could get less land and the house would have to be smaller to make it cheaper overall. Currently we are planning for it to be around 1400 sq feet "living area" plus cellar, so comfortable but not huge for a family of 4...
True, wood stoves are not very expensive, so if we do decide on the heat pump, I think we would end up getting both (with the smaller land/smaller house). You may ask, why not wait a few years to save more money? I guess because I think we may not have a few more years until things go downhill and building might not only be more expensive but also maybe impossible

mos6507 · Posted: Sun Aug 10, 2008 1:00 pm Post subject: Re: Wood stove vs heat pump?

strider3700 · Posted: Sun Aug 10, 2008 2:31 pm Post subject: Re: Wood stove vs heat pump?

Depending on your location you may not be able to get away with just wood heat. I technically have electric baseboard and a wood stove as backup since a wood stove can't be the primary heat source around here. It's not allowed by code and by the insurance people. Any place I have from here on out will have wood and some other form of heating. If building from scratch I'd be doing radiant floor heating heated by a propane boiler and solar as well as a wood stove.
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The_Virginian · Light Sweet Crude Joined: Jun 19, 2004 Posts: 1528

WisJim · Posted: Sun Aug 10, 2008 6:44 pm Post subject: Re: Wood stove vs heat pump?

A heat pump is a high tech device. Depending on where you live, you might not need a central heating system, if you insulate well, or rather insulate VERY well. In the first post, you mention a solar thermal system. What is it doing if not heating? Here in western Wisconsin I know of homes that are well enough built that they don't require any fancy heating system--they have super insulation, passive solar design, a small wood stove (often a masonry stove or Russian fireplace), and sometimes active solar connected to infloor radiant heat.