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Geothermal systems


Barony

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After living in a house for the past 5 years with electric baseboard heat, the bride and I are looking to finally put in a furnace this summer. I know that it's a lot of money, but the closed geothermal system looks like they way to go. I haven't called any dealers yet, but just curious how much I need to budget. I'll also need to add duct work and re-sheetrock the ceiling. Any advice is appreciated.

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If you looking at a "True" Geothermal heating system, one that draws heat/cooling from the ground to regulate temperature, you are into a high chunk of change. Prices are going to drastically change based a a few factors: Size of house, area to place pipes below ground, area you live in, etc.

As a GC, I would not reccoment putting this system in an existing home. The costs would outweight the benefits IMHO.

If you are talking about a closed loop underslab radiant heating system, that is gas powered, you are still talking about either removing existing concrete, or adding a 2" topping to concrete floors. Either option is not cheap.

Judging from your question, I am guessing you want to get away from the high gas prices, but I don't think the investment would have much payback unless you plan to be there for 15-20 years.

I have a whole boatload of information on "Green Building". The Geothermal and other things normaly have a 10-25 yr payback on them, unless you get into some of the incentive programs offered by city/state/federal offices to reduce gas useage. In some municipalities this is even down to below 5 yrs if you factor in tax incentives.

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Maybe I'm more clueless than I thought about this. I'm making the assumption that it can be used with a forced air furnace. Am I wrong? If it can't be used w/ forced air, then I'm going to have to look at something else. This is the home that we plan to retire someday in and the furnace will be part of a remodel on the home.

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Watch out for shady contractors. There is a lot to that kind of a system and there are a lot people out there that don't know how to set them up properly. I would suggest not going with the lowest bider (that's true for any project).

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Maybe I can help here. I maintain a mall with 7 geothermal systems using a pump and dump system. This was originally installed 25 years ago and tax credits made it economical to to so. I love geothermal and recently looked at retrofitting my house with it. After weighing all the options, I decided on a 95 percent furnace with a air source heat pump. This ran about 5 grand versus approximately 15 grand for geothermal. This would not include putting ducts in your house. In todays world a pump and dump system where you pump water out of a well and then dump it into a swamp is not recommended. That leaves 3 methods of installation. The first is to bury slinky like coils down in the soil. They are buried below the frost line and preferably in the water table. In geothermal, water is the key, because that is where the heat is. The second is to stake the pipes in wells down in the water. In both of these cases, the pipes are then filled with food grade polypropolene gylcol and hooked up to a circulation pump to supply feed to the heat pump. The last option is to bury copper pipe in the ground and run the coolant such as r410 thru the pipe using it much like a condenser on a a/c unit. The installation of this part of the infrastructure is where the cost lies in geothermal. The payback on my house would have been over 20 years. In addition, geothermals do require quite a bit of maintenence each year to run properly. If you do not have the slinkys or the wells properly sized you can run out of heat on cold winters and as such you also need a backup source of heat.

As I said, I decided on a hybrid system using a air source heat pump backed by a 95 percent furnace. The payback on this figures to be under 5 years compared to my 30 year old furnace and central air. The heat pump will provide heat down below 30 degrees with the furnace kicking in after that. A control box will turn off the heat pump if it is unable to provide enough heat or the temp is too low. The box can be set to do this at the points economical for you.

Another option, is the all climate air source heat pump by Hallowell called the arcadia. This uses two compressors and is supposed to be able to heat your home down to -30 degrees. However it has only been out a few years and I did not feel that is has proven itself as of yet.

Lastly, because of the cost of ductwork, you may want to check into high velocity systems that use only 2 inch pipes for ductwork and are specifically designed for retrofit in houses with radiant heat. They are common for a/c but I am not sure about heating with them.

Hope this helps.

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Im installing a high velocity system in a new house right now. It is hooked up to a air to air heat pump and uses a heat exchanger and high efficiency boiler. I am not sure how well they work as a stand alone furnace.

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As DrKen said somewhere in that $15K range is probably about what it will cost you to install a quality 4-5 ton ground source heat pump system. I currently have a 5 ton unit in my house and the yearly heating cost is below $400 for 3100 sq. ft. My system cost roughly $12K 8 years ago. A buddy installed a very similar system last year, and I believe he spent around $16K

They are a great heating system, and the payback can be quite quick, particularly if you consider the stability of electricity prices when compared to gas or fuel oil. (electricity prices cant change at nearly the rate gas or oil can because electricity costs are still highly regulated)

Calculating your payback time can be a bit tricky as there are a number of factors to consider, such as the fact that you also get the benefit of cooling in the summer and you have to consider the tradeoff costs of new furnce and/or AC units along with the total energy costs. Some of the manufactureres will do this for you if you supply them some basic info.

All said, I am extremely happy with my geothermal unit, and would definitely recommend it to anyone that has the space available to install the system.

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Keep in mind that air source heat pumps are getting pretty close to the COP rating that a ground source is. Im not a big fan of Geo in this climate, I do work on a few and the repairs are usually high, as is maintenance in comparison to Air source.

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I put in a FHP brand geothermal system 7 years ago in a new construction house. I have a pump and dump system, not a closed loop system which I decided on for cost savings and less intrusion in the yard to create the loop system space. My system is forced air only on both levels. The only thing I wished I had done differently would be to put in a hybrid system of forced air upstairs, in-floor in the basement as my wife likes the feel of a warm floor even though our basement stays plenty warm.

I can say nothing but positive things about the set up I have. At the time I put in my system and still to this day, I am surprised at the skepticism I hear about geothermal systems and the misconceptions that they will not perform in our climate. My contractor told me "you will not like that system and will be replacing it withing 6 months to a year." Others say I will pay for extraordinary repair costs.

In 7 years I have never had to turn on the auxilary heat plenum once. I have never touched the system except to clean the air filter. I use it year round as a heating system and a cooling system. We keep our house at 72 degrees in the winter (even when it is -30 or more below without problem.) When I compare my heating bill to my friends who have very similar houses, I figure my entire system paid for itself already so bring on any repair bill you want, it will be worth it to continue using the geothermal system in my opinion.

The pump and dump some say wastes water. I don't think of it that way. I figured once that I used no more water than someone that fills a swimming pool twice a year. Plus my water dumped simply goes into a wetland and back into the water system. In the meantime it creates a great place for wildlife to water year round.

ccarlson

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DrKen- Found the site for Hallowell and sent a link to my brother who is a Mech. Eng. for him to look at.

Man, there's a lot of options out there and I appreciate all the feedback. We have budgeted $15K so hopefully we can be in that area. A friend who is getting into Geothermal just attended a training session and shared with me that the cost of fossil fuels for heating will be unbelievable in the next 10 years.

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Hey Barony-

Have you considered electric radiant heating for your home? Geothermal systems are excellent, but very costly. Electric radiant heating is just as efficient, but a fraction of the cost. I personally know of a few people who have these systems in their home (new construction and existing homes) and really love the efficiency and cost.

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walleyepaul,

Is the electric radiant heating system you talk about the same as an electric heat storage system? The type with basically bricks that are heated off peak and the heat is drawn from them throughout the day? If so, from what I remember, that was also a good choice when I built my house. The advantage of geothermal, however, is that the system can also be used as an air conditioner to cool in the summer.

It is another type of heat that you hear little about and I feel is a good option.

ccarlson

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Where we live, they don't offer off peak for residents. That would play a big part in our decision if we were able to get that.

I've got a lot of educating to do, and for a guy who looks in the tackle box for 5 minutes trying to make a decision as to what color jig head to use, this will be a real problem when it comes to pulling the trigger. Too many options that look good.

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Best of luck Barony. In my experience I have NEVER heard an owner of a geothermal system complain about it. I have heard plenty of contractors say "You will wish you didn't" but part of me thinks it is because they don't know about them or it makes part of their job more difficult.

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 Originally Posted By: WalleyePaul
Electric radiant heating is just as efficient, but a fraction of the cost.

WalleyePaul, I have to disagree with you. While electric radiant heat is extremely efficient (nearly 100%), geothermal heat pumps capture heat from the earth and transfer it into the building, therefore they have effective efficiencies in the range of 300% - 500% In other words, for every 1kW of electricity you use, you get 3-5 kW of heat output, thats why they pay themselves off so quickly.

Barony, take a look at wikipedia, they actually have a very informative section on ground source heat pumps.

I know 7 different families that have ground source heat pumps installed as thier only heating system. Of these, only one has had any complaints. (I'd say thats fairly typical of almost any system)

Also, I believe that most of the modern geothermal systems made for residential applications are maintenance free. I know that the system I have has minimal maintenance requirements. (Cleaning the filter, oiling the fan motor)

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Think maybe I'll chip in again. Understand, I love geothermal systems and have been maintaining 7 of them for over 20 years. Originally, we had tetco's which had a life span of only 10 years. We replaced these with modern units about 6 years ago. Originally, there were backup gas furnaces and the airconditioning was just a swamp type cooler with well water run thru a coil. The new ones are reversing and provide true airconditioning. They also require much less maintenence. These are the sole hvac units for the mall in which my office is located. They have been relatively trouble free but we have had to replace sensors, 1 expansion valve, a couple of boards, and had to have one rebuilt due to a break in the system and water getting into the compressor. Currently, we have one with aslow freon leak. Each system is responsible for approximately 1500 square feet of mall space. Regular maintenence includes cleaning screens for the well water to prevent sand into the systems and changing filters and adjusting water flow from the well. I am not unhappy with them at all. We do have occassional freezeups during the summer when they are really stressed with a/c but a reset usually fixes it. These areusually due to the tenant setting a/c temps low because the units aren't quite big enought to maintain 72 degrees on 95 plus temp days with high humidity and they all think it helps to turn the stat down to 65 and they freeze up overnight. Geothermal air doesn't like to go much below 68 degrees on our units. Modern geothermal is a great system.

On pump and dump systems, remember when you draw water from a well that is 180 feet deep and dump it into a wetland it takes 100's or even 1000's of years to return down to that level. We currently, have problems with overusing our deep aquifiers and if everyone uses pump and dumps then we will have a shortage of drinking water in no time at all. Wells are also a source of contamination to the geo heat exchanger and you can deposit minerals and similar in the heat exchanger and then have to acid wash or rod out the heat exchanger. There is much less chance of this with a closed loop system.

When I ran the rough numbers on retrofitting with a geo system on my house versus a modern hybrid with a air source heat pump, I could not make a payback on the additional savings during the 3 months with the geo over the air source. During the cooling season and the transition seasons where there are temps over 30 degrees I will not be using the gas system. I am ;using a 16 seer air source heat pump and the COP at 30 degrees is 3.12 and at 20 degrees is 2.78. 20 degrees is the break even point for me between gas and heat pump where I am paying the same amount for gas or electric per therm. The heat pump will provide heat down to this level. It would be even more if I went dual source rates on the electric but excel makes you do about $2500 in wiring to do so with a new dual meter service entrance instead of a subtraction meter. Besides the heat pump is really only good down to this level. The premium to install the geo was over 10 thousand dollars and it would take years to save that over the hybrid system savings. Thus I chose hybrid. Not because i don't like geos but economics. Everyones situation is different. Besides with the backup gas heat if my electricity goes out, I can still run the gas furnace because it just draws 15 amps max and I can hook up the generator to do this but not the 40 amps or so that geos require. If you live out in the country, this is a factor to consider also. Your decision must be based on gas and electric rates where you live and the location where you live. Geothermal is without a doubt the most efficient current hvac systems out there but is it worth the premium over hybrids as air source heat pumps improve. In may case, it was not. Hope this helps as you make your choices. Modern geothermal is relaible and very efficient but air source heat pumps are rapidly closing the gap. My 16 seer was 2400 dollars with line set, expansion valve and coil. Installation will be extra. As air source improve or options such as the Hallowell arcadia prove themselves,I am sure that I could upgrade for less than the premium geo would cost to install currently. This was the basis for my current decisions. Either way you will not be umhappy.

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Not talking about machine efficiency but the amount of therms delivered to your house for each kilowatt of electricity used. With heat pumps you are transferring btu's from outside to the inside of your house not converting electrical energy to thermal energy thus it takes 1/3rd the electricity to deliver a therm of heat to your house thus 300 percent efficiency in relation to radiant electric heat. Hope this helps. There is a earlier post in this thread that explains the process

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