(800) 853-2651
SHOP NOW

OT Geothermal question

I

IaGary

Well-known Member
You guys that have geo with a closed loop system for your heat source, I have a question.

Is your loop pressurized or just a stand pipe with circulation pumps?

I have a installer trying to tell me the pressurized is more efficient. Another says it doesn't matter.

I have done some searching on the web to but have found little infro.
 
The one's I've worked on have very low pressure. Just enough to circulate. From what I've seen, the most efficient system is the one that goes out horizontally. It takes more acreage but uses less electricity and pumping power. Even better if in a deep pond. The ones that go down vertically into a deep well are less efficient since they take more power and more PSI.

And of course there are exceptions. If you live on top of a volcano, and drill down into a hotbed, I assume that will give you more heat then going horizontally in 5 or 10 feet of depth and 45-50 F degree ground temps.
 

Gary,

How deep do you have to go there to get significant heat? Estimate 3-4 feet here for heating and cooling, but don't really know. Ground has been frozen for the last few days here, maybe 3 inches deep.

KEH
 
If a vertical system has correctly sized pipes, it will have no more or less pumping effort than a flat system with proper pipes. The deeper it goes, the more stable the earth temp, (and hotter). I pumped cold coolant down and warmed coolant back up a 50ft deep well and used a small low pressure pump W/O issues. JimN
 
Where I live in central NY, once you're five-six feet down, the temp gets pretty stable (around 45 degrees F). Nothing gained going deeper. But, if you don't have a lot of property, and want geothermal, sometimes the only way to do it is to drill a one or two very deep wells. They have to have enough total length to give the water time to get heated. I'm not sure what the average is, but I know of one that has two 400 feet deep wells connected together (thus an 800 foot run).
It's easy to see where pumping water from those depths can be costly.
 
I've yet to see a case where a 600 foot vertical closed-loop system (300 foot depths) ran as efficient as a 600 foot horizontal (300 foot one-way) closed-loop system, when it comes to energy used to pump the water.

I'll admit, I haven't seen them all, but have montitored the specs on several here central NY and also in northern MI.

Unless I'm missing something, what you state defies the laws of physics. Vertical system has to overcome the weight of 300' of water. Horizontal does not.
 
Coillayedout002.jpg


Disassembledtank014.jpg


I think this tubing mat would transfer some ground source heat. It is set up in a counterflow configuration. Every other tube goes out 250 ft to a manifold at the far end. It flows to another manifold and comes back in the remaining tubes. The poly tube is 1/2". The four manifolds are 2.5" PVC. I have 28 units. Enough to cover more than two hockey rinks. In fact, that is one of their uses. For details contact wardner at peoplepc dot com.
 
I have had the wells for 15 years now no problems other than lightning about 4 years ago. It don't take any more power to circulate water in the well system than any other system. When one gallon goes up one goes down. My circulation pump is little bitty. I have a 2100 square foot home and I heat and cool it for less than $400.00 per year. I would not have any other system than what I have. Ground Source is the way to go.
 
How many feet of pipe at what spacing and how deep?
Many closed loop geothermal system installations suffer from having a too small of a field.
 
I have 4 400 foot loops of 1" plastic in a pit 6 to 7 foot deep.

The one guy says that under pressure the water will tumble more inside the pipe and transfer heat better from the earth to the water.

And he also said Carrier recommends pressurized for their furnace to be it's most efficient.
 
"Vertical system has to overcome the weight of 300' of water"

Half the water is going downhill, the other half is getting pushed back up. The pump just needs to overcome the friction.
 
We have put in both horizontal and vertical systems. They both use the same set of pumps, not very big. As the water flows out it flows in so there is no pressure to the system. You can open the tank where the water goes in and see it circulate. We are about to hook up another one this week. It has 4 vertical loops and still uses the same pump set up. We did one with the wells. They like to drill them about 180 feet and no more. Any less and they have to put in extra wells. On the one with the wells we hit rock at 140 feet so we ended up with a fourth well. Again, we used the same pump set up.You wouldn't want the water moving to fast so it has time to do the heat transfer.
 
You still use a small circulation pump to move the water thru the loop. It just is moving slow under pressure.
 
a "U" shaped hose running 500 feet down, and 500 feet back up with 1.5" ID will have the same resistance to flow as one sitting out flat on the ground. If it were a open system, pumping out of the well, and into open system. or injected a distance away, you would be exactly correct. I owned a 500 foot deep well in MT, and it took a seven stage submersible to manage the lift. But my 50 footer was easily pumped at 1/4hp. Jim
 
JD,

I enjoy and appreciate your posts as they are usually quite informative and extremely practical, so I am loathe to disagree with you. In this case, I think you are thinking about this incorrectly.

If the system is a true closed loop, you are not pumping water up from the depths as in a drinking water well, you are moving water around a wheel. That is, every gallon coming up is counterbalanced by a gallon going down. The only head the pump has to overcome is the frictional resistance in the pipe, not the height of the column.

In my area (NW IL) I have seen geothermal systems both drilled and trenched, usually decided by the subsurface conditions. On my property, I think it would be difficult to dig 600' of trench 6' deep without dealing with large rock formations.

As to pressurizing the system, I think that pressurization of any hydronic system is a really good idea largely because it makes oxygen much less of a factor in system wear.

Just my thoughts,

Phil Crome
 
OK folks I have geo system that is ten years old it is not a pressure system and uses two recirc pumps it is a Water Furnace it takes 500' of pipe under ground per ton of heating/cooling. If you want to know more e-mail me. In spite of some of the problems I've had I would do it in a heartbeat some things I'd do differently.
 
I understand the concept in theory, but the reality has been- for every system I've looked at - the horizontal was more efficent in regard to energy costs to pump water. Why? I don't know.

I've been looking into installing for a couple of years now. Since I'm on 100% solar electric, I'm looking for a system that uses as little electric as possible. That's why I've been looking closely at many types of systems.
 
Yes, that is what happens in theory. I understand the weight pressure down idea, equaling energy to push back up the other well.

In reality, I've yet to find one that runs as efficient, when compared to horizontal - in the same area and both closed loop.

I don't know enough about all the factors involved to say why, but I know enough from the specs I've read to know what the end result is.
 
I designed and installed a geo system years ago that used the pond as a water source. Was extremely efficient. Used 11/2 in pvc up and back and just a circulating pump because as the others have said there is no static head only friction loss which was small with the big pipe. If you have a near by pond it simplifies the whole thing a lot.
 
Phil is correct. In a closed loop system, after all air is removed, then the system is neutral too pressure other than the internal resistance to the piping and pipe fittings, provided that the the system remains in balance.

Only if the balance(weight) of the fluid in piping changes would you incur a pressure differential between suction and discharge.

On a liquid to liquid heat exchanger, the highest efficiency is obtained on a closed loop system.

On a closed loop system, "any" entrained air with-in the closed loop fluid would be less efficient. This is because liquid retains and transfers more BTU than air does. 2nd) we loose pumping efficiency because air will cause the pump to cavitate thus moving less gpm of desired BTU content and will shorten the pump life span.

The efficiency of a liquid heat exchanger is expressed in BTU/hr of heat transfer for amount of exchanger square feet at a given rate of flow.

Example: We have a liquid/liquid exchanger rated at 25000btu/hr@7gpm@60º∆. If we turn the flow rate upto 10gpm we would still only get approx 25000btu/hr of heat transfer.

I designed a fuel cooling station for rocket fuel using a MaQuay liquid/liquid flat plate heat exchanger that produced 25tons of refrigerating effect with a 8"x8"16" size exchanger. That was a smoking design performance for that era and still may be (very doubtful).

T_Bone<---45yrs ASHREA HVAC&R Design Engineer, Indoor Air Quality Engineer, Energy Management Engineer, AWS-CWI, Retired, Ranked in the top 60 of 150,000 of my peers, designing & troubleshooting multi-million dollar control systems.
 
I have had geothermic for 20+ years. and have had both a pressurized an non pressurized loops. Bot worked well, but i prefer the non pressurized, it has a reservoir tank that if it gets low lets more water in though i have never lost any water. With the pressurized loop if you lost even a slight amount of water you had to manually add it. My loops are 6 feet deep, and each side of loop is 2 feet apart in a single trench. for a 2 ton unit I have 2 250 feet long loops 20 feet part. I really like my unit, it is very economical to heat and cool with. One thing, if sized properly they are intended to hold temperature, not change it rapidly, so if you turn neat off or way down, then back up a fay or 2 later, it will be slow to recover. For a lot of good infl go to www.hydro-temp.com
 
I've had a closed loop horizontal system for 13 years, in a 2500 square ft house. 750 feet of pipe at 6 feet under. Mine is not pressurized and can't see any reason it would make a difference. The liquid is not compressible, so it's not going to know the difference, should perform the same either way. Other than a few problems after the initial install, ours has worked great, and I'd certainly do it again. I was told that the propane backup would be needed if temps dropped much below 20, but it handles the heating at well below zero, and never a problem with cooling.
 
Hoosier boy, I have a pond about 75 feet from my house. I would be very interested in learning about your system. Please email me.
Richard
 
IAGary,

The only benefit I can think of with a pressurized system is that you won't get any evaporation out of the standpipe. I had to add some antifreeze to my loop last winter. On the other hand, that was the first time it has been done and it's been installed since 1996.
 
Today the "pump and dump" furnace is recieving 47 deg water from a 175 deep well with a 3/4 hp pump and discharges 32deg down a field drain tile. Uses 5gpm and pump puts out 15gpm at installation test, so rest of house gets plenty when needed.Heating 4000sq ft with temps kept high for old folks living with us. Had below zero temps for days and wind. Furnace runs 80-90% of the time. Land here is loess over sand over sticky clay with glacier erratics (rocks)that get as big as Buicks, so field idea was avoided. Hard to get used to the complicated furnace and tepid heat after years of natural gas in the city. But....it works! Leo
 
Please note folks only in cooling is geo electrically efficient as far as heating as was mentioned your system will run 80-90 percent of the time during the heating season and will use electric heating elements to supplement unless you have a backup. I'm referencing an underground closed loop system I'm thinking a well system more so because of the need for an additonal lift pump the warmer water will not offset the difference. I've already researched this when I put it in also in my area you can't return the water to the aquifer due to EPA regs. so you have to collect it in a pond which is another added $$$ and more acreage. IAGary I suggest you have several quotes for their recommendations because you're looking at least double the cost of conventional systems and the ammoritization over time.
 
Cadet Trooper, I agree the initial install costs are very high, but so far as I can tell by run time, electric usage, etc., mine has very little difference in efficiency of summer or winter. Remember, they are working with temperatures at the 6 foot depth (laying on limestone in my case), not air temperature. I do have resistance backup, but it has never kicked on except when I tested it.
 
You must log in or register to reply here.

Similar threads

B
Hydraulic Pressure
Replies
4
Views
550
paul
P
R
Electrical question
2
Replies
29
Views
897
JMOR
J
Geo-TH,In
OT: There are alternatives to burning wood.
2 3
Replies
59
Views
4K
INCase
I
B
Case 530 Bendix steering function question.
Replies
4
Views
319
BearNE
B
M
Gehl HL4400 Rear Drive Pump Front Seal Question
Replies
2
Views
353
MrBiggles
M
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top