Author Topic: HVAC at end of life: oil to gas conversion or is geothermal heat pump feasible?  (Read 425 times)

Poundwise

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The situation:
Our above-ground oil tank failed and needs to be replaced in the next month; the AC died years ago; and the plumber said that our hot water heater will need replacement soon.  Boiler is very old. We have gas already for cooking. 

We're in NY state, the house is on solid rock on less than a quarter acre. We used an annual average of 670 gallons of oil a year for the past five years; paid an average of $2050/year.

I've made some calls and am waiting on quotes on a new oil tank, and also an oil-to-gas conversion. However a friend suggested a geothermal heat pump.  The heat is through hot water radiators which I understand does not work with geothermal,  but we also have unused ductwork from our defunct central air. Is geothermal a real possibility? I did some research and now have an elementary understanding of the principle, but no handle on whether this is something worth pursuing.  Mr. Poundwise is very negative on the subject; thinks it's pie in the sky.

Anybody have experience with geothermal?
« Last Edit: December 07, 2018, 01:33:38 PM by Poundwise »

ChpBstrd

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The situation:
Our above-ground oil tank failed and needs to be replaced in the next month; the AC died years ago; and the plumber said that our hot water heater will need replacement soon.  Boiler is very old. We have gas already for cooking. 

We're in NY state, the house is on solid rock on less than a quarter acre. We used an annual average of 670 gallons of oil a year for the past five years; paid an average of $2050/year.

I've made some calls and am waiting on quotes on a new oil tank, and also an oil-to-gas conversion. However a friend suggested a geothermal heat pump.  The heat is through hot water radiators which I understand does not work with geothermal,  but we also have unused ductwork from our defunct central air. Is geothermal a real possibility? I did some research and now have an elementary understanding of the principle, but no handle on whether this is something worth pursuing.  Mr. Poundwise is very negative on the subject; thinks it's pie in the sky.

Anybody have experience with geothermal?

I don't have one, nor am I an expert, but it might be the best bet for someone in your situation. The decision is about how long you'll live in the house. Geothermal costs a ton to install upfront, but then provides significant annual savings that pay off over X years, as compared to oil/gas. Given that homebuyers will be clueless, you will probably not recoup your investment if you sell in 4-6 years.

You would connect the heat pump's inside coils and fan to your existing ductwork, if clean enough, and use the ducts for both heating and cooling. No radiators necessary (but keep them for architectural charm). The heat pump is flipped from pulling heat out of the ground during winter to putting heat back into the ground during summer. The unit costs only a little bit more than a normal AC/furnace combo, but the hole drilling can be expensive. You get increased efficiency though.

I would get some quotes or arrange for consultation with agencies in your state that work on energy efficiency. Also see if there are tax incentives. The part about the house sitting on solid rock gives me pause - that might increase your drilling costs. Probably they'd drill straight down rather than laying out a grid.

As for your water heater, a regular gas water heater is probably the cheapest option. I don't think heat pumps are normally used for that.

Kahooli

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Technically you can have a multi stage heat pump and use hot water radiators. I've never seen such a system advertised as most people in the US want to have central AC, and would use the heat pump in both seasons.

Syonyk

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I don't think you're going to get away with a ground-source heat pump for hot water heating - that's a screwy enough situation that if someone did make a unit for it, you wouldn't want to know how much it cost.

Rock means going straight down, which is also expensive - you're basically paying someone to come drill a well, then run pipe down and fill it in.

Assuming you're planning to live there a long while, I'd look hard at doing an air source heat pump/air conditioner, paired with a natural gas furnace for the dead of winter.  You can use the heat pump when the air is warmer out, and you'd have to figure out the crossover point for air source heat pump vs natural gas furnace in terms of cost of heating, though if you put solar on, you may value using the heat pump down lower than is optimal.

A modern air source heat pump works down to ~-10F or so, so the old advice that you can't use them anywhere below freezing isn't accurate anymore.

I don't know if it would be cheaper/more effective to rig in a forced air gas furnace, or to put a gas boiler in for your heating system.  But if you're going to get a new air conditioner, the cost of adding an air source heat pump is quite low - it's just an air conditioner with a few extra valves and wires.

Poundwise

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I would get some quotes or arrange for consultation with agencies in your state that work on energy efficiency. Also see if there are tax incentives. The part about the house sitting on solid rock gives me pause - that might increase your drilling costs. Probably they'd drill straight down rather than laying out a grid.


Thanks for the info ChpBstrd!  I sent an email to a county website that promotes renewable energy initiative to see if they can direct me.  Also one of the gas conversion companies also advertises geothermal, so I asked them if they could give me an estimate... we will see!

Quote from: Syonyk
Rock means going straight down, which is also expensive - you're basically paying someone to come drill a well, then run pipe down and fill it in.
Yeah, that's what I'm afraid of.  But I'm encouraged by the number of HVAC companies I'm finding who offer geothermal.  If it were impossible in this area there wouldn't be so many, would there?

The idea of geothermal is so awesome.  I was also reading up on "desuperheaters". http://energysmartalternatives.com/2013/03/how-a-geothermal-desuperheater-works/

Syonyk

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Yeah, that's what I'm afraid of.  But I'm encouraged by the number of HVAC companies I'm finding who offer geothermal.  If it were impossible in this area there wouldn't be so many, would there?

Have you asked their prices?

I have no shortage of solar installers in the area, but all of them charge what, to me, are utterly obscene rates I refuse to pay...