High-efficiency furnace: how much extra do they cost?

[yesthattom]

The furnace in our tenant house is starting to fail. We need to replace it.

It is an oil furnace (forced air). However we can convert to gas (we have enough gas line capacity).

We want to go with a super-extra-efficient model, since it will pay for itself eventually.

Nobody seems to give prices on their web pages. How much of an uplift should we expect for the super-high-efficency models?

I notice many companies off “oil to gas” conversions, but none offer the other direction. I interpret this to mean that gas is cheaper. Is this correct?

Comments

[ayse.livejournal.com]

Gas is generally cheaper, yes. But bear in mind that it is a commodity, and pricing is based on supply.

The real cost in home heating is in the ductwork (if you upgrade to super-efficiency, your main loss of energy will be through leaky/uninsulated ducts rather than poor burning efficiency, so you might want to make your next step re-ducting the house). A new, ultra-efficient furnace will cost maybe 10-20% more than a low-efficiency model, but it probably will be eligible for rebates from your local utilities.

To get hard quotes, you need to call the heating companies in person. None of them want to give quotes on materials because then you will realize how much they charge for labour and you might get pissy about it (actually, the cost of labour is well-justified).

[yesthattom.livejournal.com]

Luckily there is very little duct work between the furnace and where it is going, because the furnace is on the first floor. However, the problem is that the furnace is in an unheated part of the building, so those 2 feet of duct work are a terrible heat loss. I'm going to have them insulate it as part of the contract.

[hawkwind2000.livejournal.com]

Whether oil or gas is cheaper is pretty much a toss-up at any given time. Right now, oil is going up. At some point, the monopoly that supplies yoru gas is going to take advantage of this and raise their prices. At some point the oil price will drop some, and the gas will still be stuck at teh higher price. lather, rinse, repeat.

A *new* furnace, no matter the fuel, will be more efficient than anything more than (IIRC) 10 years old.

Things to note: how is your current furnace vented? HEG vents mostly *water* -- which can eat away at older chimneys, especially near the top where it's more susceptible to outside temperatures. If you have an older house and a brick chimney, it might make more sense to go wtih someting that isn't quite so highly efficient, so as to avoid a nasty repair bill down teh line. How well is the house insulated? Could you get the tenant to shrink wrap some/all the windows, especially in the upper floors? This would help heating efficiency also, and be less expensive.
(Yes, I realize you said it's failing and needs replacing. Insulating is good anyway.) This was something we looked into a couple of years ago; it made more sense (at teh time) for us to stick with oil. I'd have to re-run the numbers again now, but I have a strong dislike/distaste for any monopolistic source.

[whc.livejournal.com]

The super high effecinecy furnaces usually vent via a PCV pipe through the wall of the house, not through a conventional chimney.

[yesthattom.livejournal.com]

> A *new* furnace, no matter the fuel, will be more
> efficient than anything more than (IIRC) 10 years old.

You know, I think that's the crux of it. This thing is gonna cut monthly costs in half just due to that factor.

[webbob.livejournal.com]

The oil to gas conversion is more likely than the conversion in the other direction because the gas utilities subsidize the conversion, I think.

You might qualify for an oil-to-gas conversion subsidy. I recently bought an 85% efficient hot water boiler for about $600, once the discount and rebate were factored in. Check out <http://www.njcleanenergy.com/residential/programs/warmadvantage/warmadvantage>, for example.

[slinkr.livejournal.com]

There are subsidies available for oil to gas conversions because switching to gas reduces CO2 emissions.

I think in most cases the subsidies come from the government and the gas utilities just market them, but I'm not up to date on this.

[misteropinion.livejournal.com]

A specific "gas-to-oil conversion" creates an ultra-low-efficiency furnace by keeping everything except for the burners. You don't want that. The gas company is excited to give you credits to hook up to their drug-pipe, but many people do and they're OK still. If you switch to gas, you will wind up either abandoning your chimney or likely putting a flue liner in because of the whole it's-just-water-vapor-now thing. When I replaced the furnace in my Ex's house it wasn't worth the extra cost for ultra high efficiency over regular high efficiency gas, but it was still pretty efficient. Lastly, even a new oil furnace will be more efficient than what's there, so you're going to have to run some comparisons on the cost to decide, but in that area I haven't got a clue, sorry.

[whc.livejournal.com]

Down here in the south, oil furnaces are getting rare and it's hard to find someone to work on them. Since ours is getting old, I did a bit of research and found a few interesting things:

Oil furnaces are usually about 80% efficient (for a new one, older ones may be only 50% or so) while gas furnaces are easily found in the 95-98% range. Somewhere in this range, they condense the water vapor out of the exhaust and vent liquid water through a PVC pipe instead of gas through a flue.

Given 80% efficiency for oil and 98% for gas, and the prices for oil and propane my supplier quoted last year, the cost is about equal. Natural gas is traditionally about half the cost of propane, but I don't have specific figures.

Figuring the relative cost is fairly easy: Find the BTU content for the fuel in question (oil is about 130,000 to 140,000 BTU/Gallon) and the cost for the fuel.

(BTU content per unit)*(efficiency)/(cost of unit) = BTU per dollar

[yesthattom.livejournal.com]

Thanks (especially for the formula!)

[mrfantasy.livejournal.com]

I know that some high-efficiency furnaces bypass the traditional chimmney altogether and just use a PVC pipe vented out a wall. They can do this since the furnace is so efficient that the exhaust gas isn't hot.

I'd think the trick would be finding a high-efficiency furnace that sized for the space. It's small, but then again, I bet it's not well insulated so you might need more capacity to handle that.

Speaking of which, you might get more bang for the buck by doing things like insulation than the payback on the furnace will provide. Do the tenants have their own meter or do you pay for their gas? I guess if the former, it's your bottom line; if the latter, then you can jack up the rent by an appropriate amount by the amount of fuel savings!

[yesthattom.livejournal.com]

It looks small, but it's actually 2 stories and a lot of space. Plus the fact that the furnace is in the closet out back (vented? it's practically outside!)

Yes, they have their own meter. And yes, we're doing insulation a little at a time. However, when this gets installed we're going to do massive insulation around the furnace itself (the ducts, etc.)

[tactisle.livejournal.com]

If your furnace is in a closet with direct access to the roof, then venting won't be a problem. Lucky you. :)

The other reason oil->gas conversions are more popular than vice versa is that there's no toxic-waste liability issues with gas. An oil tank, even the newfangled indoor variety, will eventually spring a leak and stand a chance of sludging up the groundwater.

Also, I think oil burning releases some NOx, which gas doesn't. Not a greenhouse issue, but a possible acid-rain one.

Finally, is the oil tank indoors or underground? If the latter, are you including the cost of stuffing and capping (or removing) the tank in your budget? I priced out an oil/gas conversion over here a couple years back, and they said we had to ballast and seal the tank, or pull it, if we took it offline.

[yesthattom.livejournal.com]

I hadn't thought about the cost of ballasting and sealing the tank. However, your post also made me remember that we're paying a lot for homeowners insurance because of that tank, so it might even out.

Our homeowner insurance broker had a difficult time. Many places don't insure houses older than 100 years old, other's don't touch you if you have a separate building on the lot, others don't touch you if you have tenants, others don't touch above-ground tanks. That didn't leave us much choice.

[tactisle.livejournal.com]

Whoo-ey, I hear ya about the insurance. (We got in just under the wire at 94 years old.) But if your tank is above-ground, it'll probably be cheap to remove it. Ours is underground, and we were quoted something ridiculous, 10 grand or more if I remember it right.

[yesthattom.livejournal.com]

Sadly the tank is brand new. At closing we refused the deal unless they paid to replace the tank. They did (in like 2 days flat). The thing still looks clean enough to be in a showroom.

[mtnvwpilot.livejournal.com]

Maybe you can sell it on eBay... ;-)

[yesthattom.livejournal.com]

I had only joking thought of that, but once I checked it actually seems reasonable! I'd have to say, "pick up only" of course ;)

[slfisher.livejournal.com]

The thing I like about having oil is that I fill up the tank and I'm pretty much set for the winter. It's a big financial hit but then it's done. With gas, if the price goes up, or if there's any sort of interruption in service, you're hosed.

[yesthattom.livejournal.com]

Currently we're filling this tank 2-3 times each winter. With the higher efficiency system that might be 1-2 times.

I hear that gas prices usually follow oil. I think the cost of not having to insure our oil tank will make it even less costly.