Burning wood? Natural Gas? Pellets? Too many options....
October 13, 2009 7:49 AM   Subscribe

Please help me figure out the best source of backup heat for my house!

My house was built in the 1940s, is approximately 1000 sq. feet (one story). My primary source of heat is an electric heat pump, with a gas furnace on those really cold days.

My concern is a heat source in case the power goes out. I'm in the Seattle area if it matters.

I was pretty sure I wanted a natural gas freestanding stove to use, but I started considering whether a wood burning stove or other option might be better.

I'd like to have as small of an eco-footprint as possible, though with it being the backup source of heat, it really won't be used all that often (I hope!) so it's not my number one priority. Also, space is pretty limited.

Any suggestions (including heating ideas I haven't thought of) would be most appreciated. Thanks!
posted by Zoyashka to Home & Garden (7 answers total) 2 users marked this as a favorite
If you have a fireplace or a space for one and a natural gas line, a highly efficient gas log fireplace insert can take the chill out. Make sure that it is not required to be wired in (i.e.- uses a small battery pack) and it will work when the power goes out. Some new, more efficient inserts allow venting directly into the living space, no chimney required, as the combustion products of CH4 and O2 are only H20 and CO2. This can cause dampness issues as the water vapor condenses on cold window glass in the upper floors, however. Here is some info I just googled, read up on the ventless options. I'm pretty sure that these have a smaller carbon footprint than wood stoves, but if I'm wrong I have no doubt someone will be along to correct me.
posted by kuujjuarapik at 8:07 AM on October 13, 2009

The gas-fired, free-standing, vented stoves are pretty efficient, look nice and are cozy. However, I'm sitting in front of my (EPA-certified) woodstove, enjoying the fire on a blustery day in Maine. We lost power several times last winter, and I was warm, my pipes were safe, and I could do simple cooking. I have a couple of kerosene lamps for reading light. The biggest drawback to losing power was listening to all the generators my neighbors used.

Wood stoves are a bit messy. Wood brings in dirt, sometimes bugs, and it does seem fairly dusty. Ashes have to be disposed of, and you must pay attention to safety. You have to get firewood, but if you're resourceful, there's a fair amount of free wood available, if you only use the stove occasionally. I really enjoy my woodstove.

Both gas and wood stoves show up on Craigslist, though this is the expensive time of year to get a stove because demand is high. Good info at the forums on hearth.com.

Generator = small, gas-powered engine = polluting.
posted by theora55 at 9:12 AM on October 13, 2009

A wood stove is likely going to be more trouble and expense than it is worth for backup use. You will need not only the stove, but also to install an approved chimney, possibly an outside air intake, and a non-combustible pad underneath the stove. Not only will you spend quite a bit, but the environmental impact of the manufacture and shipping of all the components will be significant. You'll also use a fair bit of space.

How long do you want to be able to heat your house for if the power goes out? If you don't anticipate a power outage lasting more than a few days, you could consider a battery backup system that would allow you to run your gas furnace. A more efficient, ECM fan for your furnace might be a worthwhile upgrade to reduce the battery capacity needed. A battery bank will also allow you to run your fridge and freezer.

If you anticipate longer outages, then a small gas fireplace may be your best option.
posted by ssg at 9:38 AM on October 13, 2009

Many older gas furnaces don't require any electricity to run. If there's a blower, maybe you can run it off a battery rather than buying another heating device.

This would save you the additional space and the eco-footprint of another thing being manufactured, delivered, and installed.
posted by yohko at 9:40 AM on October 13, 2009

I wasn't going to write about my solution, since it seemed to be going in a different direction than what you want. But a few people have written about backup power for the furnace, and that's the way I eventually decided to do it.

I had the hard-wired power connection to the furnace redone as a line cord plugged into a dedicated outlet. This is likely to be some kind of code violation in many parts of the world. But the advantage is it makes it really easy to power the furnace from either a small portable generator (which cost me less than $200) or a decent-sized battery bank and inverter+charger (which I had fun building for this).

My 1986-vintage gas furnace turns out to use only about 90 watts when running, so it was fairly practical to run it for quite some time on a couple of 12V, 100 amp-hour AGM batteries. A large computer UPS would work about as well and not require building anything.

The generator is for longer outages and does require making sure there is always a relatively new supply of gasoline for it. Every few months, the old gas goes into the car and the cans get re-filled with fresh stuff.

It seemed easier to store a little fuel for a generator to be able to get at all that heat that's available from the gas line, than to try to store enough of some other fuel to actually heat the house with it directly.

This is probably way more work and complication than you were looking for, but it's definitely possible. I probably wouldn't have done it if I wasn't the type of person who has fun hacking together things like this. Although we don't have a lot of long power outages where I live, I worry about the next 1998 ice storm or August 2003 blackout happening when it's -30 degrees.

As far as environmental impact, if I don't actually use this very often, there's really just the eventual disposal of the batteries to consider. Lead is expensive enough that they go to great lengths to recover it from old batteries these days, rather than having it end up in the ground or the air.

The gasoline I buy for the generator just ends up in the car anyway, so there's no net increase in either gasoline purchase or emissions. Keeping the batteries charged up uses virtually no power to speak of.

As a side-benefit, I can keep my fridge running if there's a power outage in the summer. Being able to run a window fan would have been really nice in that August 2003 blackout, too.

If you can't stomach the possibly code-violating and weird-looks-from-contractors-generating line cord supplying power to the furnace, there are ways to do this with generator transfer switches and outside power sockets and so on, but it's a lot more expensive to do it that way and probably not worth it at that point.
posted by FishBike at 10:04 AM on October 13, 2009

"I was pretty sure I wanted a natural gas freestanding stove to use, but I started considering whether a wood burning stove or other option might be better."

A wood stove is kind of a pain for back up use because:
  • They don't work if no one is home
  • Chimneys need maintenance even if you don't use them and you have to watch their isn't a blockage.
  • Seasoned wood takes up lots of space and attracts assorted bugs and vermin
  • Just having one installed increases your fire insurance rates
  • When you do use them they are messy, both bits of wood in and ashes out
  • Some places ashes can not be disposed of via regular trash collection
  • An EPA unit is quite a bit more money not even counting the installation cost differences over a direct vent gas stove
Personally I'd go for a nice standing pilot, millivolt freestanding gas system. Doesn't require any electricity at all, not even batteries and it can be set to come on automatically even if you aren't home via a thermostat. It's also essentially what I have except I have a fireplace insert (not gas logs) instead of the free standing stove.

FishBike has a good solution too that I have the ability, parts and skill to cobble together in an hour if it was warranted. However my large generator is propane powered so my fuel doesn't go bad. I've been considering converting my smaller generator to NG and installing the generator switch. It wouldn't come close to powering my house but it would keep my furnace, fridge and freezer running plus a few light fixtures.

One of the considerations with a generator in (sub)urban areas is theft just when you need it the most so keep an eye on securing the unit from a semi determined thief.
posted by Mitheral at 10:21 AM on October 13, 2009

Response by poster: Thanks everyone, I just spent some time at the fireplace shop looking over gas/wood options and I still don't know what I want.

Some good ideas in here regarding the battery bank and things I never even considered when thinking about going for a woodstove.

Thanks to all!

Fingers crossed that I'll be able to make a decision before Spring arrives :)
posted by Zoyashka at 12:11 PM on October 13, 2009

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