Can Someone Explain Geo Thermal Heating To Me?

[Doc995]

Last week I had a rep from a geo-thermal company contact me to see if I "qualified" for geo-thermal heat. No mention of cost whatsoever so I sent him on his way. However, my interest was piqued. Does anyone here have it? Is it reliable? Cost/year? I currently have oil and I'd say my cost for the heating season is somewhere around ~1200.00 to ~1500.00 per heating season which is November-April here in the Northeast. I should probably leave things alone, but the idea interested me...

 

[info2x]

I have a friend who has it in his new house. Loves it.

It runs a lot different than an oil furnace because the air is not nearly as hot so it runs a lot. You also (from what I'm told) don't really turn the system back because recovery takes forever or it kicks on an aux heater of some kind and blows all your savings anyways.

How well is the home air sealed and insulated?

 

[Doc995]

How well is the home air sealed and insulated?

Not very...built in 1955 and still have original windows, so there's that....

 

[JRC3]

Cheap heating, A/C, hot water...$20K up front. A friend of mine had it done a few years ago and raves. Could be justification raving. He was on propane. He got lucky and part of his decision was that there were some subsidy crazy-low interest loans to do it. He was able to use the same loan to do some other work to his home.

 

[Doc995]

Thanks for the replies! Given the situation, I think I'll stay with oil! If I ever built new from ground-up, this still seems like a great idea...for an existing older home, not so much!

 

[yeldogt]

Geothermal is a heat pump. It's just using the ground -- or water vs the outside air that a typical AC/ Heat pump that you see on the side of the house uses.

The most common type uses wells -- drilled to a depth and sized to the needed load or tons of heating cooling. The size and number dependent on building load. You can also use coils of pipe buried in the ground ... or even a pond. It's just heat transfer.

I'm a nerd with this kind of stuff and have looked into it every time I have built -- I can't make the numbers work ..even with the rebates and tax savings. The wells are too expensive and the load too high ... IE ..too many wells.

The advancements with common air heat pumps have closed the gap and made the numbers even harder to hit going geo.

Geo is taking a more steady ground temp .... vs what an air source heat pump will contend with in the winter If the ground is 55 in the summer -- it's pulling in 55 degree water vs what an air unit has to deal with ... maybe 90degree air.

What people need to understand .... 90 degree air can still take heat and air at zero still has heat. It's all pressure and refrigerant

 

[info2x]

Geothermal is a heat pump. It's just using the ground -- or water vs air that at typical AC/ Heat pump that you see on the side of the house.

The most common type uses wells -- drilled to a depth and sized to the needed load or tons of heating cooling. The size and number dependent on building load. You can also use coils of pipe buried in the ground ... or even a pond. It's just heat transfer.

I'm a nerd with this kind of stuff and have looked into it every time I have built -- I can't make the numbers work ..even with the rebates and tax savings. The wells are too expensive and the load too high ... IE ..too many wells.

The advancements with common air heat pumps have closed the gap and made the numbers even harder to hit going geo.

Geo is taking a more steady ground temp .... vs what an air source heat pump will contend with in the winter

Yeah depending on how you have to run the loops changes the cost a bunch. My buddy who did it had a large plot of land so he didn't need to do a vertical well but could just lay the loops horizontally about 8 feet down. He other heating option was LP and since he's trying to get off the grid with solar he tried to be as electrical dependent as possible.

Not sure if he broke even but that's his problem.

 

[JRC3]

^My buddy is on a 1/2 acre and they did the 8' thing too, only in his back yard (1/4).

 

[yeldogt]

Yeah depending on how you have to run the loops changes the cost a bunch. My buddy who did it had a large plot of land so he didn't need to do a vertical well but could just lay the loops horizontally about 8 feet down. He other heating option was LP and since he's trying to get off the grid with solar he tried to be as electrical dependent as possible.

Not sure if he broke even but that's his problem.

There are situations where you just have to pay the price ... the ground pipe method is great if you have the space and the temps are in your favor ... you can also do partials where the system will do 80% and you need a backup.

My current project needed 60k worth of wells -- just the wells. That buys a lot of propane and power. In my projects -- spending on spray foam and good windows was the better way to go. This reduces the load = smaller equipment. smaller/ better equipment = lower operating cost. Still more than geo .... but, you can't have 30 year paybacks. Geo equipment is more money .....one thing that has changed. Pumps -- they are much more efficient ... old geo pumps could be expensive to run and replace

 

[juddspaintballs]

The big problem with geothermal is sizing it. You can properly size it for your head load and climate, but if you get an unusually cold snap, you can literally freeze the ground your geo loops are in. Then, your geo heat pump is useless for heat until it thaws. You can't use any of your auxiliary heat sources to thaw it, either.

Fairly big upfront cost, not terribly common parts to repair it if it breaks ($$$), and the problem of potentially freezing your loops. The ROI is a long shot, but geothermal still isn't a deal breaker. If you have a tight, well-insulated house, geo makes more sense, but even then there are other efficient heating methods that make more sense for less money.

 

[Bert_]

Lots of cheaper ways to save money.

 

[zendriver]

I once work for a plumber friend who sold and installed/service them. He never installed one in his own home.

Great for cooling, so so heating and stinks when really cold,Requiring electric strips or hybrid gas/oil add on.

They seem to require a lot more maintenance and repair than other heating cooling methods, none of it cheap.




Sent from my iPhone using The Garage Journal mobile app

 

[American Locomotive]

As mentioned, geothermal systems are just heatpumps that use the ground as a heat source/sink instead of the air.

The two big things against them are
1) cost. If you have to drill a bunch of vertical wells, it's going to get real expensive real fast
2) modern air source heatpumps (mitsubishi hyper heat, etc..) now provide usuable heat at extremely low temperatures. As low as 5F.

There might be some edge cases where it makes sense to go geothermal, but you'd really have to crunch the numbers.

 

[toplessHO]

Ive been using geothermal for almost 50 yrs.
One of the pioneers in the development was an engineer that I worked closely with and sold some of his systems. At the time he had clientele all over the world.
I have only had 2 systems in my house in the last 40 yrs,and both have been pretty much trouble free. The first was a Florida Heat Pump,second is a Bard.Im not sure I understand the comment of high maintenance.I have no need for backup heat,other than one cold Christmas day the power went out and we stoked the fireplace to keep the house above freezing.

MY COP is over 4 and its hard to dispute the numbers.I get 4tons of cooling and 5.5tons of heat out of my system.

 

[American Locomotive]

The heating needs of central Florida are significantly different than Connecticut, where the system would see far heavier use, especially during the winter.

Most modern air-source heat pumps can provide heating COPs greater than 4 down to freezing temperatures.

 

[jlv03]

The heating needs of central Florida are significantly different than Connecticut, where the system would see far heavier use, especially during the winter.

Most modern air-source heat pumps can provide heating COPs greater than 4 down to freezing temperatures.

Wouldn't the cooling needs of central Florida be significantly different than CT? I guess I'm not understanding the argument.

I think you have hit the nail on the head why geothermal is becoming a hard sell, the air-to-air heat pumps keep getting better, plus insulation has much more of a focus. Throw in dirt cheap natural gas and you end up in a situation where a geothermoal heat pump may never pay back for the average homeowner that moves every 5-7 years.

 

[JRC3]

Throw in dirt cheap natural gas and you end up in a situation where a geothermoal heat pump may never pay back for the average homeowner that moves every 5-7 years.

Not all homes do or can even have NG.

My buddy who has it of course brags about the cheaper cooling in the summer. But what do you do to remove the humidity?

 

[theoldwizard1]

To understand geothermal you first have to understand how a heat pump works. a heat pump is basically an air conditioner run "backward". It tries to "cool" the outside and you get hot air on the inside. Heat pumps run in both directions so you get cool air in the summer.

Geothermal just means the outside source is the ground water which is pretty close to 55F all year. There are two ways to get cool ground water. 1) Lay loops of pipe buried about 10' down. 2) Drill wells and run a loop of pipe to the bottom.

The big problem with geothermal is sizing it. You can properly size it for your head load and climate, but if you get an unusually cold snap, you can literally freeze the ground your geo loops are in. Then, your geo heat pump is useless for heat until it thaws.

This is why I would NEVER install a horizontal loop system ! At least with a vertical loop system, you can add another well.

I many southern states, all new municipal building MUST use geothermal. Expensive to install but cheap to run !

 

[Bert_]

Not all homes do or can even have NG.

My buddy who has it of course brags about the cheaper cooling in the summer. But what do you do to remove the humidity?

Not sure what you mean about humidity? It will pull humidity out of the air the same as a standard A/C

 

[yeldogt]

Ive been using geothermal for almost 50 yrs.
One of the pioneers in the development was an engineer that I worked closely with and sold some of his systems. At the time he had clientele all over the world.
I have only had 2 systems in my house in the last 40 yrs,and both have been pretty much trouble free. The first was a Florida Heat Pump,second is a Bard.Im not sure I understand the comment of high maintenance.I have no need for backup heat,other than one cold Christmas day the power went out and we stoked the fireplace to keep the house above freezing.

MY COP is over 4 and its hard to dispute the numbers.I get 4tons of cooling and 5.5tons of heat out of my system.

Geo works .... it's all about cost. I just can't make the numbers work ---

 

[theoldwizard1]

Geo works .... it's all about cost. I just can't make the numbers work ---

True ! Even worse for a retro fit. Pay back is long.

 

[nadogail]

I have read of Geothermal heating systems fed by geysers and piles of decomposing manure. Cooling was handled by a large pond.

If you have available sources of heat and cold, make use of it.

 

[Captain Spaulding]

I once work for a plumber friend who sold and installed/service them. He never installed one in his own home.

Great for cooling, so so heating and stinks when really cold,Requiring electric strips or hybrid gas/oil add on.

They seem to require a lot more maintenance and repair than other heating cooling methods, none of it cheap.




Sent from my iPhone using The Garage Journal mobile app

WE’ve had ours for 11 years and the backup heat has never been on and the only maintenance that’s ever been done is adding a little water as air was displaced the first two years. Air temperature has little effect on how they work because the operate down in the ground where the temperature is close to constant year round.

 

[reader2580]

I looked into geothermal back in 2008/9 when I was considering building a new house. The quote for geothermal back then including the ductwork was $26,000. I never did build a new house as I couldn't sell my house at the time. I am pretty sure there was a 30% tax credit at the time.

Fast forward to 2014 and I sold my house. I then bought a relatively small house that had electric baseboard heat and did all new HVAC. It cost me $21,000 for natural gas furnace, central A/C, and all the ductwork since the house had no ductwork. I had forgotten about geothermal so I never asked what that would cost.

Where I live the electric CO-OP offers a very low rate for electric heating if you have automatic backup heat for days when the CO-OP needs to cut power to your electric heating. Automatic backup heat means you need a propane/gas furnace/boiler or similar that can start unattended. You can't use a wood stove or similar as backup. I am definitely going to look into geothermal when my furnace starts to age. I am only six years in right now on my gas furnace.

 

[theoldwizard1]

Great for cooling, so so heating and stinks when really cold,Requiring electric strips or hybrid gas/oil add on.

Then the heat sink/source was sized wrong !

This problem is common in horizontal loop systems installed in the upper midwest. If the return water from the loops is below about 40-45F, your screwed !

The thing is, no one ever installs a thermometer to measure the temperature of the return water and there is never a clause in the contract that states what remedy would be applied if the return water is too low.

 

[jkeyser14]

Then the heat sink/source was sized wrong !

This problem is common in horizontal loop systems installed in the upper midwest. If the return water from the loops is below about 40-45F, your screwed !

The thing is, no one ever installs a thermometer to measure the temperature of the return water and there is never a clause in the contract that states what remedy would be applied if the return water is too low.

That's not true. Find a certified installer and they will guarantee the loop temperatures and measure them when the system is installed. My thermostat even has a display of incoming vs. outgoing loop temperatures and refrigerant temperatures that you can monitor.

 

[jkeyser14]

I have had geothermal in 2 different houses now and love it. Our current house is 3000 sq. ft. with a 700 sq. ft. heated and cooled garage. I also have a Tesla Model 3 that I put about 25,000 miles on per year and only charge at home.

My electric bill is $100-150 in the summer and $150-$200 in the winter (family of 4). Thermostat in house is set at 70 year round. The garage is kept at 60 in the winter and 80 in the summer, unless I am out there working.

The payback period is only 7 years, and that is with a very low electricity rate (currently $.12 / kwh including all taxes and fees).

 

[yeldogt]

I have had geothermal in 2 different houses now and love it. Our current house is 3000 sq. ft. with a 700 sq. ft. heated and cooled garage. I also have a Tesla Model 3 that I put about 25,000 miles on per year and only charge at home.

My electric bill is $100-150 in the summer and $150-$200 in the winter (family of 4). Thermostat in house is set at 70 year round. The garage is kept at 60 in the winter and 80 in the summer, unless I am out there working.

The payback period is only 7 years, and that is with a very low electricity rate (currently $.12 / kwh including all taxes and fees).

No one should dispute that they work -- it's all a question of the cost of the equipment.

Where Geo shines are large buildings with low cost of drilling wells -- no NG available.

It's always been more logical for me to spend the money building a better building and lowing the needed conditioning equipment.

 

[American Locomotive]

The payback period is only 7 years, and that is with a very low electricity rate (currently $.12 / kwh including all taxes and fees).

7 years compared to what? Pure electric resistance heat?

 

[yeldogt]

That's not true. Find a certified installer and they will guarantee the loop temperatures and measure them when the system is installed. My thermostat even has a display of incoming vs. outgoing loop temperatures and refrigerant temperatures that you can monitor.

As you get into colder climates the cost of the loops and equipment can get to a point that the systems max out. Say -- you hit 5 tons and you need more. Do you do a second system .... also -- it's common to need an additional well for the odd very cold temps that may occur only a few days a year. How much is that well and what's the payback for just that period?

 

[LS6 Tommy]

I've seen a few really nice geo systems. All of them also had some sort of backup. It really is a matter of how much you want to spend.

Lots of cheaper ways to save money.

That is an excellent phrase. I'm going to remember it.



Tommy

 

[HoosierBuddy]

I agree with earlier posters that the improvements in air-source heat pumps have made geo-thermal a solution to a problem that doesn't exist anymore.

In my experience at the gas co., I've run into several GT installations over the years where we are asked to run in a gas service in the middle of the winter as the ground loop on a GT system has failed (leaking)...they have no clear idea of where the loop even lays exactly to try to find the leak or fix it....the system has reverted to backup/emergency (i.e. electrical resistance) and bills jump up over $1000/month.

In that situation...if you can get NG...and the utility will run you a service in the middle of the winter....you end up switching to a NG furnace just to stop the pain.

Any heat pump that fails can cause the same problem. It reverts to resistance heating and 80% of the public doesn't even realize anything has happened (not like the 20% of us that hang out on GJ). If anything, they may notice their house feels a bit more comfortable because the air coming out of the vents is going to be significantly warmer. Then they get that first bill and: 1. They call the power company to tell them they must have misread the meter (sorry no). 2. They call their HVAC guy to get the unit fixed.

By then, they are well into the second month of emergency/backup operation...so they need a heat pump repair or replacement AND the power company is going to nail them with another big bill.

Gas furnaces are so much more informative. When it quits working, you will BY GOD, know it has quit working....because you won't have any heat at all. It's like "a feature".
Phil

 

[kj_mustang]

I had a quote for a geo system for my new construction home about 5-6 years ago. Ground loop system with me digging the trenches was quoted over $60,000. I did two heat pump systems for less than $30,000. With a very well insulated home, my electric bill isn't that high to justify that much upfront cost difference.

 

[weedy64]

Finally something I have experience with.

I agree Geo works and can be cheap enough if you are capable and don't need a contractor or permits etc. I guess it all depends on your situation: shop size, available water or excavation equipment.

I am on the West Coast, I rebuilt a house and installed radiant floors it was setup to take a standard boiler or ?? in the garage. When the time came I opted for a Geosource HP. It heated the house all year, we had no electric plenum heaters, but we had a couple decorative gas fire places. We heated a pool in the shoulder seasons as required. The unit also preheated the electric domestic hot water tank, to the point that it would not turn on in active heating season. AC was not deemed a reqd so no cooling coils were installed.

I spent about ~14K in 2004 for the 5T W2W unit and the in-ground field. A contractor installed the pump and field. I believe a boiler\install was about 5-6K at the time.

The install has never required any service work.

I sold and moved on.

In my current shop, 1400sq with 4 bays, 3 bays 10ft ceilings, 1 bay16ft ceiling. It has an old 30ft surface well beside it, which I use as a source of 45deg water. I pump from the old well and dump on the back side of the building where eaves water runs, the gravel base lets some of the water find its way back to the well. Its all about 300yds from a major river so it doesn't seem like the water table changes much, and the ground water tmp varies maybe 2deg.

I bought 7-8 pullout Daikin H20 source heatpumps from a bank reno, 4 year old units $100/T +$50 for each depending on the size. (new heating contractor refused to use old equip) I have a single circ. pump(200W) to feed filtered water to the 2ea 2T ceiling W2A units and I use a wifi staged thermostat to remotely adjust the T when I want to go to work in comfort. It will cool or heat as required, provided the bay doors are closed. I have maybe $1000 installed in that shop. The only thing I dislike is the fan noise, I should get some soft ducting to dampen the noise or install the boxes above the ceiling but Id rather not expose them to freezing rafter temps. I dont really notice the electric cost as I run welders, lathes, mill, compressor etc.

 

[jkeyser14]

Not all homes do or can even have NG.

My buddy who has it of course brags about the cheaper cooling in the summer. But what do you do to remove the humidity?

It still removes the humidity just like a normal air conditioner.

 

[jkeyser14]

7 years compared to what? Pure electric resistance heat?

Compared to a normal heat pump. It was even faster payback than propane or oil heat. Natural gas is not available in my area.

 

[jkeyser14]

As you get into colder climates the cost of the loops and equipment can get to a point that the systems max out. Say -- you hit 5 tons and you need more. Do you do a second system .... also -- it's common to need an additional well for the odd very cold temps that may occur only a few days a year. How much is that well and what's the payback for just that period?

You never need an additional well for short periods. If your system was installed by an idiot and was undersized the electric backup heater would kick in on those days. But if you hire a competent contractor the well will be appropriately sized from the beginning.

 

[jkeyser14]

I had a quote for a geo system for my new construction home about 5-6 years ago. Ground loop system with me digging the trenches was quoted over $60,000. I did two heat pump systems for less than $30,000. With a very well insulated home, my electric bill isn't that high to justify that much upfront cost difference.

Sounds like you got the "go away" price. My new construction home with multiple zones and desuperheater were far less, and I am in a high cost of living area.

 

[JRC3]

It still removes the humidity just like a normal air conditioner.

Not sure what you mean about humidity? It will pull humidity out of the air the same as a standard A/C

I had it in my head that 55 degree ground water ran through the A-coil and the house air flowed through it...After I thought about it I realize it probably has a compressor just like a regular A/C condensing unit, but instead of air flowing across the conenser coil, it's water. 55 degree water on a 90+ degree day is way more efficient than 90+ degree air.

Same applies to it being a heat pump in the winter. Instead of trying to pull heat out of 10 degree air, it's pulling it out of 55 degree water.

 

[American Locomotive]

Compared to a normal heat pump. It was even faster payback than propane or oil heat. Natural gas is not available in my area.

I really don't believe that. Unless your geothermal system was <$3,000 installed.

Your geothermal system would basically have to use literally 0 electricity for the payback to be 7 years compared to an air-source heatpump.

Sounds like someone did the calculations against an old-school R22 heatpump that would be running with the aux resistance heat on most of the winter.