OT Geo Thermal vs boiler

Putting up a new shop and alot of locals have the boiler system for their in floor heat, but had one neighbor tell me i should look into geo thermal? Never really heard much of it and what the pros and cons are of it, your guys input would be greatly appreciated

We put up a new building 72x120 with a 72x80 heated shop and 32x32 attached office area. We have geothermal heat and air in shop and office. Wasn't much more for the air as long as the geothermal field was in. Definitely more expensive up front but with power co. rebates and extra efficiency the system should pay for itself in 7 years. Here in NW Minnesocold the floor heat is sure nice. The system wasn't up for the cooling season but I am looking forward to greasing the combine in AC comfort. Doc.

If you have modest depth for water wells on the property, drilling two wells about 50 ft apart into the same source works wonders. The water is pulled from on and injected into the other with minimal pumping losses, and no depletion of water. The water is very close to uniform temp all year, and provides an efficient source of heat and cold. Even if it is a pumped loss system, and the pumped water is surface discharged into a pond or creek, it will be more efficient and less expensive over time. Purchasing pellets, or natural gas, or propane will be radically more expensive. Cutting wood is OK when you are 50 not when you are 80. Jim

It depends on what your alternatives are. If natural gas is available, it's going to be very competitive with the best geothermal system, and dirt cheap to install. But if propane, oil and electric are your only alternatives, then you should check out geothermal.

I would definitely put the heat in the floor. I have an electric boiler, that I will probably change out to propane. Propane was very high when I put it in.

I would do natural gas if you can, geothermal if you do not.

Just remember if you are planning a system like that then you must be in an area that gets down to well below freezing so if that is the case and then you get a storm that knocks out the power for a week or longer and there have been several storms lately that power was out for a month that the heating system if not used will possibly end up being froze sollid so you need to figure in for a backup system to keep the system operating. I don't know how much electricity they require to operate but any system that requires power to operate you need to figure a way to keep power to it.

I live a cold area and know two contractors,neither use water to circulate thru the system,they are closed loop systems.

Couple factors to consider for going with Geo. First is the 30% Federal tax credit it qualifies for. That is 30% of the total system including labor the the government will credit to you if you install one. The credit is a check back, not a tax deduction. Second a lot of states will give a real estate tax reduction for installing one. Third check with your power supplier as they may offer rebates. Fourth, the power company may offer reduced rate besides the rebates.

A couple clarifications concerning the use of water in the system and freezing up. Water is used in a closed loop system meaning the water never leaves the tubing but is recirculated. We put methanol in with the water to make an antifreeze. I have seen the water temp as low as 25 degrees and still circulate and heat just fine. Other guys use an antifreeze solution instead of the methanol but that is more expensive. You can do 2 wells like someone said but you will need permits to dump water back into the second well plus a bigger circulating pump to pump the water up out of the well. A Geo system will give you the most efficient cooling system there is for basically very little cost.

You still have the system that converts the water heat over to anouther system and the water from the well or underground loop going thru the pump could freeze even if you had anti freeze in the system under the floor, there has to be a conversion point someplace to transfer the heat from one side to the other and that is were the problem would be, those examples probably have that point in a well insulated area that did not go with out heat long enough for that to freeze.

I am running geo-thermal for my house. My bill is 1/2 of my neighbors and I heat twice the square footage. Mine is forced air so you get the free benefit of AC. I had no natural gas at the house so it was an easy choice over propane/oil. I don't know if you can get the cooling effect from geothermal in your concrete during the summer.

Right now my shop 40x60 I have overhead radiant heat (propane). Works great but not exactly cheap. Looking for a used geothermal unit, and eventually will convert it over.

Rick

I would say it depends on your age and alternative heat options. I just built a 5 star plus energy star rated house on a lot that is just perfect for closed loop geo. Right now I have propane heat and was astonished that with my big south facing glass I just paid $200 for a year's worth of propane (believe it or not the sun through the windows does the most). Both my neighbors have geo (much older, less efficient houses). I looked into geo and the price of installation was insane. No matter the rebates or savings I couldn't get a payback in my expected remaining life time.

Jim

The water in the closed loop system has the anti freeze in it. It circulates out in the ground loop and back to the heating unit for as you say the "conversion". To make it work for an under floor system, you need a different heating unit to heat the water that would be in the tubes under the floor. A little different set up than say a forced air unit but the same principle. Most newer forced air units have a thing called a "de-superheater" in them. It sends warmed water to your hot water heater. This circuit takes the actual cold water from your home water system and circulates it through the geo unit to get it warmed and then sends it to your water heater. Basically how the in floor system works. One closed loop circuit takes the water out to the outside ground to pick up the ground heat and the other circuit takes the heated indoor water and circulates it under the floor. They never intermingle. If properly protected with anitfreeze the ground loops should never freeze. Same for the in floor loops. The circuit for the hot water heater does not contain antifreeze as this is the same water as you would use for your house. If that freezes, you will have a lot of other freeze points also.

Smart move. Keep it simple, low tech, cheaper to fix. No repair costs in insulation and good windows.

Look at the maintance costs and life expendency of geo or heat pump. Does anyone have a 25 year old geo that has been trouble free?

Just put in a new heat pump a couple of weeks ago. Wanted geothermal but the bid was $24,000 and I couldn't justify it in this 100 year old house. There's a pretty good chance the house will fall in before the warranty is half over.

Around here they drill 300 foot wells for ground contact. The trenches don't work with the rock we have. Essentially you pay for the holes (I needed three) and the rest is free. I sure wish I could have done it cause the bills are great, but the replacement was kind of a surprise and I would have had to borrow lots of cash.

My system was installed in 93 and it needed help getting started in 94 and it has not had anything but new filters since then. It is an open system and the well pump died two years ago. The well was drilled in 78.
sde

So you have a pump and dump, not a closed loop that tends to leak? 18 years in heat pump years, is a very long time.

Just wonder, how many concrete floors crack, settle and shift over time? If you had pipes in the concrete, wouldn't that crack the pipe?

No plans to have heat in the floor, but if I were I think I would put the pipes in a layer of sand, then cover with concrete. May be less efficient, but wouldn't have to worry about shifting floor breaking pipe.

Closed-loop, forced air geo-therm. 3 horizontal loops, central Iowa. Eight years old. Paid for in 7 years, including one replacement pump. Put it in when we doubled the square footage of our house. The heat/cooling bill stayed the same as when the house was half the size. Couldn"t be happier with it.