HVAC in 1843 house: what would you do?

[BethW]

Hi guys,
I've been reading your forum constantly lately, trying to decide how to heat and cool our old house. I'm a rank novice, though, and my head's starting to spin I sure could use your thoughts.

Here's what I can tell you. Our house is 165 years old. Current heat is a Lennox oil furnace installed in the 1950s It's a dinosaur in every way 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 keep hearing that an air-source heat pump won't keep us warm in an old house, not even in this climate. I tend to agree. Which leaves me considering LP gas (natural gas not available), a high efficiency oil furnace, or geothermal.

For what it's worth, cooling the house isn't a problem. Our highest power bill last summer was 2085 kWh/$196 for July.

What say you all?

[gary_g]

I keep hearing that an air-source heat pump won't keep us warm in an old house, not even in this climate. I tend to agree.

Beth:

That statement is wrong. An air source heat pump should do a fine job in your climate if it is properly sized and installed (and ductwork checked).

Take care.

[RyanHughes]

I agree with Gary. And you can also have LP or oil as backup heat. I think you'd agree that it's worth the investment to replace the dinosaur with rising oil costs. It's older than I am. Do you know the cost of electricity, oil and LP in your area to compare it all using a fuel comparison calculator? Good luck.

[beenthere]

LP isn't cheaper then oil for heating in most places. Your area could be different.

A dual fuel heat pump, may be your best bet. Operating and installation cost wise.

That would give you the economy of a heat pump at the warmer outdoor temps(say 35 and above) and the higher discharge air temps of the LP furnace when its colder out.

What is your electric rate. And what will LP cost you per gallon. Will you be buying, or renting the LP tank. Keep in mind, that if you rent the tank, rent is charged per gallon.

[gary_g]

It's older than I am.

...but it's still only half as old as BeenThere

[RyanHughes]

Another point:

As Gary mentioned above, it's important to have the ductwork checked. If it's original to the oil furnace (and it likely is), then it may not be sufficient for a newer system. That's why it's important to have it examined by a professional and make changes where necessary. Also, it would be prudent to have a load calculation to confirm proper sizing of both the heating and cooling equipment (heat loss and heat load), especially with an older house.

[fsq4cw]

I’d get a quote on geothermal if you have forced air. With a COP of ~3.5 that would bring your cost down to ~ 2.5¢/kW, or less with a higher COP. Get rid of the oil furnace.

SR

[BethW]

We're having a load calc done in the next few weeks. The guy said it would take around 4 hours. I'll ask about the old ductwork, too. It's the old rectangular type. It does all run in the interior walls. No ductwork in unconditioned spaces.

Here are the rates from this past winter: LP $3.19/gal, oil $3.42/gal, electric 6.22¢. We own the LP tank.

We had really considered geo, trying to get away from fossil fuels. But it's still so expensive. Then again, it all is, if done right. Right?!

[beenthere]

It cost more to heat with LP then with oil at the prices you posted.

[beenthere]

1,000,000 BTUs delivered Electric resistance heat $18.20

1,000,000 BTUs delivered oil heat at 82% efficiency $29.80

1,000,000 BTUs delivered LP heat at 95% efficiency $36.50

[BethW]

I’d get a quote on geothermal if you have forced air. With a COP of ~3.5 that would bring your cost down to ~ 2.5¢/kW, or less with a higher COP. Get rid of the oil furnace.

We've gotten a general quote for geothermal, and it's definitely at the top end of what we can afford, but we'd do it if the numbers add up. Clearly, geo wins when comparing it to the highest efficiency oil furnace, but what about in comparison to a dual-fuel setup, which would probably be half the price of the lowest end Waterfurnace?

[beenthere]

At the rates you posted.
An air to air heat pump with electric aux heat would be cheaper to use the a dual fuel with oil or LP aux.

Set up right. An air to air, can keep your house warm no problem.

[a0128958]

We've gotten a general quote for geothermal, and it's definitely at the top end of what we can afford, but we'd do it if the numbers add up. Clearly, geo wins when comparing it to the highest efficiency oil furnace, but what about in comparison to a dual-fuel setup, which would probably be half the price of the lowest end Waterfurnace?

If:
- You're able to get a good analysis on optimum size (capacity) of heating/cooling your residence needs, and
- You're able to get a good, solid design/installation for the water system and the air distribution system, and
- You've got the room/resources on your property for the water system, and
- You can stomach the up-front installation cost,

Then:
geothermal is indeed 'the real deal' as far as very low operating cost - and incredibly so at your $0.0622/KWH rate. A COP of +/- 5 is a realistic expectation of the current models from manufacturers like WaterFurnace.

Unfortunately:
The 'Ifs' are significant.

I have WF equipment, and I was approximately at 5 COP when I measured it earlier this year when I was in heating mode. Similarly, my EER (cooling mode) at the moment is in the low- to mid-20s, right where WF advertises it at.

Good luck with your research and decisions.

Best regards,

Bill