Geo thermal heat pumps

Do a search on Geothermal and you'll find some data, including inputs from me.

The cost of a geothermal heat pump depends on the size and difficulty of installing the geothermal loop. In any case I'd say expect to pay a lot more than $7,500 even for a small unit.

I paid about $12,000 15 years ago for a multispeed Water Furnace (Still on the market, and mine has been trouble free and efficient). My house is just over 2000 square feet and a two story with an all electric insulation construction. The unit was designed to hold the house at 70 degrees with the outside temperature at 0 degrees, of course that means the heat pump would be running 24 hours a day in high speed. It also has two stages of resistive heat for emergency and supplemental heating. The resistive heat has never been on other than when I bring the demand temperature up too fast.

At the current electric rates in NJ and the efficiency of my heat pump, it cost me less to heat with electricity than with wood if I have to buy wood at the going split and delivered costs.

That could explain the unexpected low cost estimate, just the heat pump. I paid about $8K for the Heat Pump and installation in ducts designed to handle a HP and about $4K for the ground loop, two 250' vertical loops, put in by a well drilling outfit. My property is too rocky to "plow" a horizontal loop, which is less expensive is you have sandy soil, few to no rocks.

I've always been intrigued this type of set up. But I'm assuming that it would not work well in northern areas that have deep frost levels? Probably I'm missing something.

Deep frost levels outside the arctic are a few feet down. That's the key behind geothermal, the outside air temperature makes no difference. Heating at below zero or cooling at over 100 degrees, the geothermal is working against "deep" earth temperatures. Here in NJ that is around 50 degrees year round.

My system is a closed loop, thus the BTU transfer hast to take place through the walls of the ground loop. An open loop system would pump water from the water table, run it through the heat pump and pump it back into the water table. This mode is not allowed in NJ, but has some clear advantages from the efficiency point of view.

karl said:

I've priced 4 ton geothermal units at about $3500. I figured the work in the yard would be the big expense. My father-in-law used to own a core drilling business too bad I didn't have him drill the holes while he still had the equipment.

My research shows one hole per ton is what they are using. They go 150-170 feet deep. The other way is to dig a hole and bury a slinky type array of pipes in the ground. They dig it about 6 feet deep and im guessing 5 or 6 feet wide and 75 feet a ton long. Thats alot of yard to tear up. I'd rather drill the holes.

I think I'll look into having a well dug. I've been wanting one for irigation purposes for awhile. If the flow is enough. I'll have them dig a return well and do the open loop system.

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You'll need the well, but will have to put the loop in it. Most jurisdictions don't want you to reinject anything back into the ground. There's too much of a chance to contaminate your aquifer. Sorry!

Parental units were quoted $30K a few years back for 2 GSHP systems in new construction totaling 6 tons. This was including ductwork by a "Gucci" contractor and all the bells and whistles EXCEPT wells. They ended up with an air to air heat pump instead.

I think the price will drop as more contractors get some experience under their belts and more manufacturers come on line. The biz is still in its infancy, IMHO.

I refuse to call it "geothermal". Besides GSHP is easier to spell...

Chris

BeGreen said:

Yes, I suspect the $7500 for a 3 ton unit is just for the heat pump and not for the outdoor setup which can cost more than the actual heat pump. Then there is the tying in to the existing system. My new heatpump system was about $9K and I did most of the ductwork.

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Geothermal was insanely priced for my place. I can't even remember. We ended up with an air-source, completely installed, with dehumidifier. It was $6,000 installed in 2006...and they did all of the retrofitting for our old house that didn't have ANY ductwork. Man, BG, if mine was $9K and I had to do the ducts, I think I'd still be without anyhting but wood heat, and nothing for these sticky Ohio summers! Some of our "crawl spaces" are about 6" high. I still can't figure out how they gots the duscts through that...

I think if I had to rely on a heatpump for year-round heating and cooling, though, I would have looked a lot more closely at geothermal. The only time these past two years that we NEEDED the heatpump were the few days in January when child #2 was born and we were at the hospital. We would have lost some plumbing fixtures for sure without it. If I remember correctly, it was hovering around 17 F for 3 days straight.

Geothermal does pay if you use central heating /air-conditioning. I did not use any wood or other supplemental heating over the last twelve months and I'll estimate my 12 months electric total at about $2,400, or $200 a month. We have about the same summer weather as much of Ohio, and the A/C is on now and has been on most day-time hours for the last 7-10 days. We have no other energy sources, electric cooking, hot water, washer and dryer (and my wife uses the cloths dryer some, I do not, I use the cloths line). Of course lights and tv, most lights are high efficiency units. I believe the average American household uses about 1000 KWH per month, my average is only 30% above that for an ALL electric house.

As noted in my signature and other posts, I have installed a new Quadrafire Insert in my first floor fireplace and I do plan of burning some wood for heat this coming winter, as much as possible with "free" wood I gather. If I have to pay $300 a cord for hardwood, my heat pump may be cheaper to heat with...conditioned on a continuing gradual increase in the cost of electricity (almost totally coal and nuclear here in NJ). This insert and the coal/wood air tight in the basement are otherwise for emergency or enjoyment of a toasty warm room on occasions.

Editorial addition: The new Quadrafire installed is over $4,000. This approaches the cost Mike paid in 2006 for a new air-to-air heat pump, installed. So, when justifying investment, wood has some work to do before I can payback to cost of the new insert.

BeGreen, thanks for the reference numbers. Yes, in the mild climate (I lived in Seattle 1958-66) there is no need to go geothermal, a high efficiency air-to-air should be close to as energy effective, and with your wood supplemental heating you've got a near optimum cost environment.

My dad has a Water Furnace at his cabin in the woods. I was there yesterday to meet the contractor who had to replace the compressor (it was only 2 years old). I believe he paid something like $10,000 for new construction. Anyhow, it was under warranty, so nothing more than an inconvenience..

As the contractor finished up and the goethermal system was humming along, I walked outside and realized how silent it was. I know that my air-source heat pump really makes a lot of noise (when you're used to listening to the wood thrushes and towhees).

This, in my opinion, is one of the huge benefits of geothermal. No outdoor noise, no unsightly outdoor unit. Complete silence.

Yes, the absence of any outdoor unit is a plus, and that means all your equipment, save the ground loop, is inside and protected from weather. Im still running my Waterfurnace without any problems/failures, now over 15 years. Keeping my fingers crossed.

I have people come into the house in the summer an be amazed how cool it is in the house...i.e., they don't see an external unit and come in programed that I don't have A/C...I say we have a geothermal (or ground source) heat pump. We're on a large property, several acres, so the noise of an outside unit would not disturber neighbors, but the quiet, no sound/noise, would be very welcome to near by neighbors in a development type area.

Question for you guys:

I'm in the VA mountains with an old AC unit that should be replaced at some point. We have a wood insert for heat and electric baseboard for backup. I'm thinking about replacing the AC unit with a ground source heat pump at some point. I have a backhoe so the ground loop installation cost is minimal.

What do you guys think? Is it a good move?

As said, I installed one, paying the full cost of installation, and the unit has paid dividends $$$ every year, and now saves me thousands every year over the cost of the equivalent oil heat. Of course, if you don't use it, i.e., heat with wood, it will not pay for itself. Note, it should be much more efficient at A/C too, an ERR of 20+ at 100+ degrees air temperature (independent of air temperature) whereas an air-to-air will not give more than 12-15 at high air temperatures.

Kirk22 said:

Question for you guys:

I'm in the VA mountains with an old AC unit that should be replaced at some point. We have a wood insert for heat and electric baseboard for backup. I'm thinking about replacing the AC unit with a ground source heat pump at some point. I have a backhoe so the ground loop installation cost is minimal.

What do you guys think? Is it a good move?

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If you plan on staying put for a while, a GSHP is the best long term investment that you could make in HVAC, other than a wood stove, of course. That being said, how's the rest of the house? If your insulation isn't up to snuff and you ductwork is poor, you are never going to be happy and may just wind up damaging the equipment. The geology is also going to play a factor also. If your yard is full of rocks (like mine), you are going to have a heck of a time burying all that tubing. Also ask yourself the question: Is it worth spending close to $10K on something you are going to only use a few times a year? If you are really using the wood insert a lot, the savings will be minimal and may not be justified. A conventional air-air heat pump makes very good sense in this case. They also need good ductwork and insulation, but are less than half the cost. Even electric baseboard is a good deal if you only use it a few times a year.

Chris

This thread has got me thinking - prior to wood, we were using 800-1000 gallons a year. Now we're down to 200 with solar HW and wood. I'd love to eliminate the rest.

Has anyone done a GSHP exchanging with their domestic water well? I know our well was drilled 800 feet deep and then hyrdrofractured - after which there is a huge amount of water available.

While this one loop wouldn't do the entire house on its own, I'm wondering if it would be a good cost effective solution to eliminate the end of our oil use, as well as providing A/C? In the summer we use at most two 5000 BTU window units during the worst periods - lots of big trees for shade.

-Colin

A friend of mine is conditioning his whole house summer and winter with a GSHP using his well water reinjecting it into the same well. I'm not sure it's code, but it works! His only complaint is that his drinking water is 80+ degrees in the summer. It seems to me you will pay more to heat your HW, but this could be offset by a desuperheater coil on the heat pump. Hot water in the summer is almost a freebie!

I am going to wonder out loud how much pump horsepower you need to bring water up from 800 feet and how this compares to those two little air conditioners. It may not be worth it in the long run...

Chris

Redox said:

A friend of mine is conditioning his whole house summer and winter with a GSHP using his well water reinjecting it into the same well. I'm not sure it's code, but it works! His only complaint is that his drinking water is 80+ degrees in the summer. It seems to me you will pay more to heat your HW, but this could be offset by a desuperheater coil on the heat pump. Hot water in the summer is almost a freebie!

I am going to wonder out loud how much pump horsepower you need to bring water up from 800 feet and how this compares to those two little air conditioners. It may not be worth it in the long run...

Chris

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I seem to think that once drilled through and hydrofractured, the water table actually ended up being a lot higher. But I doubt that discharging an open loop to the well is code anyway - I was wondering if once can simply insert a closed tubing loop into the well for heat transfer, in which case the pump load would be much lower as well.

From what I've read, you can get something in the 12-15,000 BTU range out of a typical vertical well used for these systems. I'm also guessing they are not typically as deep or large as a drinking well, in which case maybe you could get closer to 20,000 BTU. I think that would be enough to easily stay warm with the 3-4 cords of wood I burn off the stove, and would be enough heat to keep the house from freezing when on vacation, enabling me to quit using oil. I'd also convert our first floor to radiant to make the job easier - only place I'd need baseboard is supplemental heat for upstairs BRs, and that could be run at 140 F and still do the job.

-Colin

If using a closed loop then you aren't really lifting water 800', the circulation pump only sees the losses due to friction through that long loop. Your domestic pump is probably pretty stout. Also remember that even though the well might be 800 feet deep, the domestic pump might only be 300-400' down. Sometimes the water fills up the well once you get to it.

If your pump is not at the bottome then you are asking for trouble trying to sneak a circulation loop down beside it. It would sure stink to get it all jambed up in there.

Highbeam said:

If using a closed loop then you aren't really lifting water 800', the circulation pump only sees the losses due to friction through that long loop. Your domestic pump is probably pretty stout. Also remember that even though the well might be 800 feet deep, the domestic pump might only be 300-400' down. Sometimes the water fills up the well once you get to it.

If your pump is not at the bottome then you are asking for trouble trying to sneak a circulation loop down beside it. It would sure stink to get it all jambed up in there.

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That's kind of what I was getting at - closed loop would have very low power requirement.

Not sure how easy it is to tuck something else down the same well. Copper would give you some rigidity to help keep it out of the way on the side, and would be awesome for heat transfer, but that could get pricey quickly. And not sure how much clearance there would be to take a well pump up and down.

-Colin