Heat pump or geo for 1843 house in Virginia?

15 years ago

Hi all,

Our house is 165 years old. Current heat is a Lennox oil furnace installed in the 1950s. It's a dinosaur but it works well, it's just that to stay warm we'll need another mortgage. Cooling is a 5-7 year old Ducane unit. The house is a clapboard with 2 1/2 stories with a finished English basement (brick foundation). 2600 square feet. It's obviously not very tight, but the exterior walls are insulated (don't know the R value) and we have 18 inches of blown insulation in the attic. Windows are original but have been restored, tightly weatherstripped, and we have good storm windows. Everything that can be sealed has been.

I've had conflicting opinions as to whether an air-source heat pump will keep us warm in an old house, even in our moderate climate. My parents (who live in the same area) installed a high-efficiency heat pump with LP backup and aren't happy with the high heat bills even though we just had a warm winter. We're seriously looking into geothermal but aren't sure the payoff would be enough in a moderate climate.

For what it's worth, cooling our house isn't a problem. Our highest power bill last summer was 2085 kWh/$196 for July. Rates from this past winter were as follows: LP $3.19/gal, oil $3.42/gal, electric 6.22Â¢. Natural gas isn't available.

What do you all think? This is hopefully a long-term house for us so we want to do it right. Thanks!

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Comments (6)

tigerdunes
15 years ago
beth

what area of country do you live?

with that low electric rate, you have to consider high eff HP or geothermal. keep in mind though, you will not have the same toasty feeling you get with oil winter heating. One thought depending on your low temperature range, you might think about dual fuel-high eff HP paired with LP gas backup furnace.

for an old home like yours, I would start with a GC experienced with old homes and have a complete professional energy audit performed. And yes you will probably have to pay for this. well worth it!

IMO
bethw
Original Author
15 years ago
Tigerdunes, thanks for your response.

We're in Virginia. I do worry about not feeling toasty since that's important to DH. That said, with the price of oil, we kept the thermostat at 60Â° last winter so anything new will seem warmer!

We're planning on having a load calc done soon (at $500, yikes) that hopefully will help our decision. I can't help but wonder though, if geo might be the way to go since the cost of a high-eff dual fual HP will start approaching the entry-level Waterfurnace (~13k).
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Mike, we paid about $3000.00 last year for propane, and that was to heat half of our home. We could close off half of it, and that's what we did. Propane cost varies widely, from almost two dollars a gallon to almost three dollars a gallon. electricity is about 9.2 cents a kwh. We have only had the bedroom and one other room cooled with a window air conditioner. We only had one real cooling month after the system was installed, and it cost $5.00 more than the month before when we were running the window a/c 24/7. Yes, we were on the downhill side of the cooling season, but we were also cooling the entire house. I really can't give you an accurate estimate of what the cooling costs will be. Our first heating month, we used about $52.00 additional electricity, and during the second month it was about $240.00 additional. I just went out and read the meter, and with 6 or 7 days until our next reading, we're on track to be the same or less than last month, so another $240.00 - $250.00 for the third heating month. We have our two coldest months ahead of us, but if I figure $350.00 each for them, then $250.00 for March, and even $250.00 for April, I'm at $1750.00 additional for electricity,(and I think that's overestimated) against $3000.00 for propane last year. And, keep in mind, that's heating the entire 3900 sq feet to a comfortable 70 degrees rather than about 2000 sq feet of it to a chilly 67-68 degrees. Well, I should clarify that it isn't all heated to 70 all the time, due to the zoning. We keep what used to be the cold half at 66 now unless we're using it, then we can quickly raise it to 70 as well. Anyway, based on my preliminary calculations, we will reduce our heating costs 40-50% keep our cooling costs about the same, and raise our comfort and enjoyment levels tenfold. Will the savings pay for the installation costs over and above a standard heat pump system? Probably, but it'll take a while. If I had it to do over, I wouldn't change a thing. Hopefully I can still say that a few years down the road.
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tigerdunes
15 years ago
beth

$500 just for a load calc? That's absurd! I hope you are getting more for your money than just that.

IMO
bethw
Original Author
15 years ago
Ah-ha! Good to know. I thought it seemed very high as well. They told me it would take four hours to complete and the cost would be applicable towards the purchase of the system, but I thought it sounded a bit much also.
marknmt
15 years ago
Hi Beth,

If you search this forum "geothermal heat pumps" or "Climatemaster" or "Tranquility 27" you should find my thoughts and warnings about the matter. After a year and a half with the new system I still like it, but there are some things to be aware of. (And it occurs to me I might have posted those things on the Renewable Energy for the Home Forum instead of this one, so you might check over there too.)

Our 1200 sq. ft. stucco is nowhere the challenge your house is, but our climate may be a little more daunting, except we never get hurricanes in Montana ... :-) Our monthly power bill, including an outrageous $40/month just for gas to heat our water, is $125.00. Our household water useage is about $25/month and we irrigate with a pump, so that's covered under the $125.00. So gas, electric and water, including irrigating, all told cost us about $150/month. We're two people in our late fifties. Do a lot of watering but otherwise pretty modest in our habits. We have an electric range. We keep the house at about 65 F in the winter and won't resort to the heat pump for air conditioning unless it gets too uncomfortable to sleep, and then we'll just use it for a few hours in the evening to take the edge off. That'll probably be for a few weeks in August, but who knows. We're conscientious about opening the house up in the morning to cool it and closing it up when it begins to warm outside. I doubt you have that option, but it works for us.

Good luck,

Mark
garyg
15 years ago
Operating cost of 1 million btu's of heat as a comparison.

Oil at $3.50/gallon, 80% efficient furnace:
(1,000,000 btu / 139,000 btu per gallon) x $3.50 / .8
= $31.47

Propane at $3.25/gallon, 80% efficient furnace:
(1,000,000 / 91,000) x 3.25 / .8
= $44.64. $39.68 for a 90% efficient furnace.

At the above prices, oil is 30% cheaper than an 80% efficient propane furnace. Oil is 20% cheaper than a 90% efficient propane furnace. What will oil be next heating season? $4.25/gallon?

Resistance electricity at 7 cents per kw-hr:
(1,000,000 / 3413) x .07
= $22.27. Half the cost of 80% propane.

Air source heat pump, same electricity costs, COP = 3.25 at 35F ambient:
= $22.27 / 3.25
= $6.85. Dirt cheap. 650% cheaper than propane to operate.

Below about 32F or so, the heat pump will require auxillary heat.

Your electric costs are so cheap that you should consider a heat pump with resistance electric back-up/auxillary heat.

Geothermal is great for the next owner of your house, since you will pay $25k for the system and the next owner gets the operating cost benefit.

Good luck.

Heat pump or geo for 1843 house in Virginia?

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Heat pump or geo for 1843 house in Virginia?

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