Alternatives to heating with oil

March 4, 2008 7:39 AM

Let's assume, for the sake of argument, that home heating-oil prices treble over the next five years. Would it be possible to retrofit a domestic hot-water baseboard system for an alternative fuel?

. . . And if the answer's "yes," what fuel or fuels would provide the most bang-for-the-buck? And what would a retrofit entail, assuming that the guts of the system--the pipes carrying hot water through the house--are kept intact?

posted by Gordion Knott to home & garden (14 comments total)

If you are asking "can I burn bio-diesel in my existing boiler with only modest upgrading and save money" you would have to think that near substitutes for heating oil would be roughly the same price as heating oil, absent some sort of tax/subsidy to muddy the waters.
posted by shothotbot at 7:52 AM on March 4

Bio-diesel is pretty much interchangeable with regular heating oil for a furnace application, but you should of course check with a real furnace technician.

Per the previous comment, anything interchangeable with diesel is going to basically cost the same as diesel.

You may be able to switch to a gas-fired boiler, but that would be a lot more expensive I expect.
posted by GuyZero at 8:00 AM on March 4

A ground source heat pump will do what you want. Models exist that power hydronic systems as well as forced air. They're electric powered and because they pump heat rather than burn electrons, they're very efficient.

Alternately, a forced air wood boiler ala the Tarm Excel is pretty flexible in terms of feed stock.
posted by seanmpuckett at 8:02 AM on March 4

You can replace an oil boiler to a gas boiler without much problem. You just need the gas line. This is going to be much better as GuyZero said above.
posted by Pollomacho at 8:06 AM on March 4

Your heating system is nice in that the method of getting heat into your house is pretty much independent of the heat source.

Basically anything that will heat water could be made to work with your system (with varying levels of effort/expense)

You could get an outdoor wood boiler, or an indoor pellet boiler.
posted by davey_darling at 8:33 AM on March 4

As others have said, you can replace the heat source with pretty much anything you want.

Gas would probably be the cheapest in upfront cost and you will likely be able to use a tankless hot water heater/boiler to supply both hot water and heat. Wood will likely cost more upfront, but fuel costs may be less. Outdoor wood-fired boilers can cause pretty bad emissions, so be careful there. A ground-source heat pump will be very expensive in upfront cost, but quite cheap to operate. You can also consider a hybrid system with solar hot water heating on your roof, which has a high upfront cost, but no fuel costs, obviously. A tankless hot water heater plus a solar system could be a good option.

The retrofit would be as simple as replacing the current boiler with something else. If you go with gas, you'll need a gas line to the boiler, a new vent, and possibly an air intake.
posted by ssg at 9:03 AM on March 4

A ground source heat pump will do what you want. Models exist that power hydronic systems as well as forced air. They're electric powered and because they pump heat rather than burn electrons, they're very efficient.

We’re in the process of finishing a new house with a ground source heat pump. (vertical closed loop, water to water system) Our house isn’t fully buttoned up and the heat is set low for the time being but so far it’s working really well.

A couple of things:

Unless your current HVAC system is very inefficient you should first spend money on insulating your house and replacing the windows. You’ll get a much better ROI that way.

Once that’s done you should be able to replace your oil furnace with a ground source heat pump (GSHP) though I’m not sure a GSHP could put out the water temperature you’d need for forced hot water baseboards. You’d need to talk to an HVAC guy about that. Generally, GSHP systems work “slow and steady.” I’m getting about 110 degree water out of the heat pump which goes to air handlers to convert it to warm air. I’d guess your oil system puts out hotter water. Unlike an oil or gas system where you walk into a cold house, crank up the thermostat and you’re warm in a few minutes, a GSHP works best if you just leave it at a constant temperature. I guess there’s no reason why it wouldn’t work with forced hot water though I’m not sure what it would do to the efficiency. You’d also loose one huge advantage to a GSHP, cheap A/C. Unless you added duct work you wouldn’t be able to do A/C.

The bad news is it can be costly. If you can do an open loop, where you pump ground water through the system, and you don’t have to go down very far to get that water, it will cost a lot less. If you can’t do an open loop the next cheapest option is a horizontal closed loop, where they lay a bunch of pipes (or coils called slinkies) about six feet in the ground. This requires a bit of land and it’ll all be disturbed when they dig it up. My only option was a vertical closed loop. We drilled two 400 foot boreholes, each with a ‘U’ pipe in them to make one big loop.

All in all I think with forced hot water baseboards it might not be worth it for you. Still, it’s worth reading up on.

I would look into one of these fireplaces, which heat your whole house using positive pressure.
posted by bondcliff at 9:06 AM on March 4 [1 favorite]

Depending where you live there may be regulations about burning solid fuels due to smoke production. I know pellet stoves are pretty efficient, but they're still not natural gas. YMMV if you live somewhere where you can burn solid fuel with impunity (e.g. the country).

Apparently you can burn corn too but I expect the price of corn will go up just like fuel oil.
posted by GuyZero at 9:07 AM on March 4

Natural gas is the cheapest option. A tankless water heater doesn't quite have the power to run a hydronic system on its own, but coupled with a solar hot water heater it would probably do the trick.
posted by electroboy at 9:23 AM on March 4

Or what ssg said.
posted by electroboy at 9:24 AM on March 4

FWIW If you cannot get NG to the house you can substitute Propane for Natural Gas in any of the above answers.

bondcliff: If I may ask; what did your vertical loop system cost you? How bad (or easy) was the drilling?
posted by Gungho at 9:32 AM on March 4

Gungho, drop me an email if you want specifics.

The drilling was bad only because we didn't hit bedrock until we were 200 feet down. Everything before the bedrock had to be cased in iron pipes, which jacked up the cost. It also disrupted the yard a bit, though that was already disrupted due to the house construction. They drill up a lot of mud in the process.

How far down they have to go depends on the size of your system.
posted by bondcliff at 9:55 AM on March 4

Since they were mentioned, I just thought that I'd drop in to say that you should be very careful if you start considering wood-fired boilers. Their smoke production is huge, and they've been specifically banned in some places for this reason. Because they essentially surround the firebox with water, they don't burn hot enough to really be clean.

This may not be true of all models but it's the case with several of the cheaper ones. Better designs would (and may) burn the wood in an insulated firebox, so it can get very hot, and then boil the water with the hot exhaust gases. (This 'fire-tube' design isn't anything new, but it adds manufacturing complexity.) Anyway, just something to think about.

Also, although I know this is a little tangential to the question, the other possible solution for your heating needs aside from retrofitting the central-heat system would be installing some sort of additional heat source. E.g., install a wood or pellet stove in one of the living areas. Some of the "EPA stoves" can be terrifically efficient and even have blowers so they produce convection, rather than just radiant, heat. I suspect that one of these installed into a fireplace, or even into a through-the-wall flue, would substantially lower your dependence on oil ... if you have a steady and inexpensive supply of cordwood.
posted by Kadin2048 at 12:24 PM on March 4

The baseboard radiators are really the cheapest part of your heating system, unless you've got some fancy European models. So you should not be too hung up on sticking with that delivery method. You'd be best off rethinking your heating operation from scratch. That includes, as mentioned, doing as much tightening and insulating as possible. Then evaluate the various fuels and distribution methods.
posted by beagle at 2:29 PM on March 4