Thread: Geo thermal heat pump

Need some info on geo thermal heat pump installation, please.

One installation quotes 3/4" ground loop (closed) at 6 foot depth and total length of 2400 feet.

Another installation quotes - 3/4" ground loop (closed) at approximately five foot depth and total length of 1,115 feet.

Both horizontal loops, closed, and soil conditions damp sand/gravel.

What is the benefit of longer loop vs. shorter loop?

Used in conjunction with 2 stage compressor, 4 ton and desuperheater for domestic hot wate assistance.

Hopefully I have provided enough info?

Thank you.

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I would like to here replies as well. I just inspected my first one in probably 6 years. This had 3 250 foot deep lines straight down into the ground.

It had been so long since I even saw one I had to differ it. They tenant purchaser had more technical knowledge about it than I did. He really did not need it inspected. When ever something goes wrong it is very expensive for repairs as he eluded to.

Originally Posted by Ted Menelly

I would like to here replies as well. I just inspected my first one in probably 6 years. This had 3 250 foot deep lines straight down into the ground.

It had been so long since I even saw one I had to differ it. They tenant purchaser had more technical knowledge about it than I did. He really did not need it inspected. When ever something goes wrong it is very expensive for repairs as he eluded to.

It depends on what goes wrong! If the water in the well goes dry then it is a major problem, and this can happen during a drought. Most of the time the pumps go out. Outside of that it, their operation is similar to a conventional heat pump, just without the outside condenser unit.

Vertical loops are from what I have read are used where locating horizontal loops would be restricted due to small lots, trees, lot lines, etc.

Btw the reason I am asking is because I am seriously giving consideration to installing a geo thermal heat pump. Thus far I have heard nothing but praise and big energy savings.

Originally Posted by Raymond Wand

Vertical loops are from what I have read are used where locating horizontal loops would be restricted due to small lots, trees, lot lines, etc.

Yes, a small lot.

Even though this home was built in 79 it is still a pretty small lot. The knowledge stored in the old brain cells just has not been accessed in so many years I did not feel competent in inspecting the system.

There is not a lot to see. When I see these systems I always defer to contractors for assessment.

Originally Posted by Raymond Wand

What is the benefit of longer loop vs. shorter loop?

The greater amount of earth the geo thermal transfer loop is in contact with, the greater the effectiveness of the geo thermal transfer loop.

Think of it this way, which would be more effective in providing geo thermal transfer:

a) Closed loop in a small pond, loop takes up entire bed of small pond.

b) Closed loop in a large lake, loop takes up entire bed of large lake.

Which one, a) or b), will heat up or cool down quicker based on the geo thermal transfer from the unit trying to cool or heat a given house (same house both either scenarios).

Which one will provide geo thermal transfer longer while remaining at a more stable temperature?

Here is one quote I rec'd, for your information:

- TTV049AGC01ARKS 4 Ton Next Energy Tranquility 2 stage Geothermal Heat Pump with ECM Motor and desuperheater for domestic hot
water assistance.

- Climate Master Digital Programmable Thermostat with red back-lite display for fault code read out and emergency heat alert.

- 10 KW back up electric heater

- Anti-vibration sound pad for below heat pump with 2 3/4" lift.
- Washable electrostatic filter media

- 2400' 3/4" heat transfer tubing in or parallel reverse return heater system buried at 6' depth.

- 26-99 Dual flow centre with 3-way valves flush ports and foam fitted composite cabinet.

- 1 1/4" connecting lines to ground loop and sealed at wall penetration with foam and interior piping is insulated to prevent sweating during heating and cooling seasons.

- Electrical all low and high voltage wiring for heat pump, backup heater and thermostat also includes necessary breakers.

- 40 gal bottom feed giant green foam pre-heat tank for use with desuperheater.

- All related plumbing for the desuperheater pre-heat tank and connection to the finishing tank all pre-heat lines are insulated.

- Duct system will be altered to accommodate new heat pump supply plenum, return elbow will be insulated to reduce noise and flex connectors installed to reduce vibration.

- 25% ethanol anti-freeze solution for freeze protection.

- Removal and disposal of the old equipment and a/c unit with proper reclaim of refrigerant and disposal of oil and oil tank.

- Excavation of ground loop stripping of topsoil and replacement after settlement to grade.
- Commissioning of unit and customer instructional.

- Assistance with paperwork for all applicable grants and name of reputable energy auditor. (Right now due to government rebates (Federal and Provincial) in Ontario I can get back $8,255.00 back on a system which is quoted at $24,400.00.

Next Energy 1 year labour, 5 years parts, 10 years compressor and 2 years workmanship by installer.

NextEnergy Geothermal | Products for Home - Tranquility 27

Thanks Jerry, a longer loop is the way to go, more contact with the earth equals better heat/cool transfer. Also I like the fact the loop is buried one foot deeper at 6 feet as opposed to the first quote I obtained which was buried a 5 feet.

Here is the computer generated report on my current forced air oil costs and electric 60 gallon hot water tank compared to the geo thermal unit with hot water preheater. As you can see there are substantial savings.

Originally Posted by Raymond Wand

Also I like the fact the loop is buried one foot deeper at 6 feet as opposed to the first quote I obtained which was buried a 5 feet.

Raymond,

You are in Ontario, right?

What is your "frost depth"?

You will want the geo thermal loop well BELOW frost depth to get good heating from it.

Kind of like taking heat from an ice cube, yeah, there is heat in there, but it would be much easier to get a lot more heat out of that much 'not-frozen water' (i.e., 'warmer water'). The 'warmer' the water, the easier it is to get more heat out of it.

Remember, when you take heat out, cold is left in its place. How much colder can it get and it still provide 'heat'? I would not want to depend on that "10 KW back up electric heater" - that would be expensive to operate and not heat very well in a cold climate (unless the space was small and very well insulated).

Raymond, sounds like you are not getting an apples to apples comparison.

One installation quotes 3/4" ground loop (closed) at 6 foot depth and total length of 2400 feet.

Another installation quotes - 3/4" ground loop (closed) at approximately five foot depth and total length of 1,115 feet.

The 6' depth at greater length will give you more heat by far. The deeper your lines, the more stable the earth source heat. The closer to the frost zone the harder to get the heat since the ground will be at a lower winter temperature. How deep are footings required to be in your climate?
I can't imagine the need for an electric resistance back-up heat source if you have sufficient ground source. (But then I don't know your climate.)

The efficiency of geo heat pumps do not fall off like with air source and there is no defrost cycle.

They may be including the electric heat on the smaller system which should translate into a smaller initial installation cost but would mean you would be using electric resistance heat to supplement during extremely cold weather, and thus larger utility bills.

I would try doing a payback calculation on the initial cost vs. operating cost. And get both companies (assuming different companies) to give an apples to apples bid.

Jerry

Our frost depth is 4 feet but very seldom does it get that deep and dependent on snow depth.

The contractor told me that the heat back up would only be needed on the coldest of days (-18 F) and the heat pump (2 stage compressor) is most always running in the first stage, then kicks up to the second stage, and finally with the second stage running and output cannot meet demands it is further backed up with the auxiliary heat. With fuel prices climbing, it is almost practical to go back to electric heat. Personally speaking we will never see cheap fuel prices again, and you can bet they will only go up. Was speaking to an electrician the other day and he agreed that electric heat may make a big come back fwiw.

My electrical bill is about $130 per month, but get this... I am charged a delivery charge for the hydro of $78.59, a further charge labeled regulatory charge of $15.00 and a further charge labeled Debt Retirement Charge of $16.00 plus taxes on these extra charges! So almost another half of my energy use is taxes!

Average Frost Depth
http://www.soundfootings.com/pdf/US_...t_DepthAVG.pdf

According to this document I am about 35-40"

Raymond,

Forget about linear feet of line right now, how large of an area is the geo thermal loop going to be installed in? 20' x 20'?

How large is your basement?

Think of the geo thermal potential 6 feet down below your basement floor ...

Good morning Jerry,

The area that the loop will be installed is approximately 350' x 100' and can be larger if needed.

My basement is approximately 450 sq. ft.

Raymond: Be sure to include in your calculations the overall electrical usage, including the back up heater and all the pumping. Since it appears that you live in a cold climate, please consider putting your money into a superinsulation package for your home.

Some experts in the field are suspicious that heat pumps may save little if any energy in the form of fossil fuels consumed (it's different of course if your electricity comes from hydro; the ramifications of nuclear energy include the always-troubling problem of radioactive waste with a half life roughly equal to one-eighth of the age of the earth.

Improvements made to the envelope of your structure will perform indefinitely at the same level, while heat pumps burn electricity and must, of course, be replaced at the end of their service life (15 years? 18??)

Given an insulation system that eliminates air leakage and provides at least R-10 under the basement floor, R-20 at the basement walls, R-40 in the walls of habitable space, and R-60 at the roof, the building can be heated with a very, very small space heater, and your only other electrical usage on the mechanical side would be for an HRV to provide fresh air and spot ventilation for kitchens and bathrooms, and maybe a water heater.

While I remain steadfastly unconvinced that heat pumps are either "Green" or "highly efficient," I have heard a talk by an engineer from Alberta who reports good results with water source heat pumps. In the end, I believe that air sealing and insulation are good, more air sealing and more insulation are better, and air sealing and insulation to a near Net Zero Energy standard are best.

Thanks for turning on the light in my head!

Beach house is about 150 yards form the beach. My outdoor units are only lasting 5-7 years, electrolisis eats the aluminum fins right off.

The lot is very small 50 X 100' so I would have to look into vertical installation. Good part is the water level is only 6-7' down, and its sand. I could almost rock the pipes into the ground like setting an umbrella on the beach.

Has anybody seen these at the beach? What kind of environmental permits etc. would I need?

Originally Posted by Vern Heiler

Beach house is about 150 yards form the beach. My outdoor units are only lasting 5-7 years, electrolisis eats the aluminum fins right off.

The lot is very small 50 X 100' so I would have to look into vertical installation. Good part is the water level is only 6-7' down, and its sand.

What kind of pipes would you use to combat the salt water corrosion of the pipes stuck down into that salt water? Anything metallic that you could stick down into the sand on its own would be gone in a few years.

Wonder what the heat transfer reduction is by going with CPVC or PVC instead of metallic? I imagine it is considerable.

As the idea has only gust been brought to my attention, I have only looked at one site. It seems that some use PVC, don't know how well it works? One idea I am kicking around is to drill 6" wells, use perforated casing, and drop a zinc rod in with copper tubing. I don't know .

Ed

While your suggestions have merit, there is no way I am about to be able to upgrade my 55 year old house to your suggested levels. To do so would be extremely costly and would require major upgrades, far beyond what the heat pump would cost.

To all others who took the time to reply; thank you very much!