1 -600ft or 2 - 300ft or 4 -150 ft holes

[taswank]

Hello,

I had an open loop installed last summer and should have chosen closed loop. I picked the open because of the increased efficiency and lower initial cost. I used my existing domestic well (25 gpm) and had tests done to confirm the water quality was good. I had changed my whole house filter about every 4/5 monthes prior to the Geo but now I have to change it every 5 days because it clogs up. I have clay problems like I never had before I guess due to the massive increased water use. I checked around for a backflushable filter system but nobody will touch it. So I have now decided to convert to a Closed Loop. My installer says my 4 ton unit should have 4 - 150' holes. I was thinking about 2 - 300' or even 1 - 600 foot hole instead. It just makes sense to me that there would then be less connections buried underground that could be potential future problems. I have asked around and nobody can give me a definitive answer what is best. Any help would be appreciated.

[yorkguy]

Hello,

I had an open loop installed last summer and should have chosen closed loop. I picked the open because of the increased efficiency and lower initial cost. I used my existing domestic well (25 gpm) and had tests done to confirm the water quality was good. I had changed my whole house filter about every 4/5 monthes prior to the Geo but now I have to change it every 5 days because it clogs up. I have clay problems like I never had before I guess due to the massive increased water use. I checked around for a backflushable filter system but nobody will touch it. So I have now decided to convert to a Closed Loop. My installer says my 4 ton unit should have 4 - 150' holes. I was thinking about 2 - 300' or even 1 - 600 foot hole instead. It just makes sense to me that there would then be less connections buried underground that could be potential future problems. I have asked around and nobody can give me a definitive answer what is best. Any help would be appreciated.

There are many factors that determine the depth the holes can be drilled such as bedrock etc. this will be for a qualified driller who knows your area to determine. Don't concern yourself too much about connections, when properly installed and tested by a good contractor the heat fusion connections are stronger than the pipe itself. Keep in mind longer loops will increase pressure drop and affect pump size and capabilites. As long as the system is designed carefully and fits the conditions there is no significant advantage one way or the other for longer vs shorter loops. Many people see a slightly higher COP upfront on an open loop and jump to the conclusion that it is much more efficient but forget about the electricity that the well pump uses vs the usually much smaller closed loop pumps as well as increased maintenence. I don't discourage the use of open loops when feasible but I don't sell them as more efficient. Also, have you tried a sediment trapper at the inlet of your heat pump for the well water?

[yorkguy]

Also, I forgot to mention that you should not be running your heat pump through your whole house filter, you will never keep with the demand of the geo. And hopefully your not running it throuh a water softener either, as that will never keep up either. The geo should have it's own branch directly after the pressure tank before any filters softeners etc. and you should have a fine mesh strainer or I prefer a clear bowl spindown sediment trapper with a drain valve on the bottom for easy cleaning before the inlet of the geo. A knowlegeable installer should know these things and be able to help you. Make sure any product and lines going to the heat pump are properly sized for the flow rate of your application.

[taswank]

The installed did speak of using a spin down type filter originally but chose the cartridge instead. I don't know why he did but I'm stuck with it. I thought about doing what you suggested before but my concern is that the filter isn't clogging with any type of particulate, it is clay slime. I don't believe a screen or spin down would stop the stuff. I changed all my copper to pex last summer also and when I cut one in half a couple weeks ago to put another tap in, I was amaxed at how much brown slimey crap was on the inside of the new pex, and this is after the cartridge filter. I am concerned that the Satinless Steel heat exchanger in the Heat Pump is already like that and it would only get much worse without the cartridge filter. Wouldn't this buildup affect the efficiency of the heat pump? I just think I should suck it up and convert to Closed Loop now and not have to deal with or worry about this in the future. I would try redoing the plumbing and adding the spin down if there is a good chance it would fix it long term.

[yorkguy]

Do you have flowmeter so you can see how many gpm you are running? :censored:
I don't understand the censored or what for I did't use bad language or anything can some one explain???

[taswank]

I don't know what the censored means either. I do have a flowmeter for the system. Florida Heat Pump says it should run at 12GPM. With the 40/60 pressure switch for my well pump, it is set at 12GPM at max pressure but drops to around 10 at min pressure. As the filter starts to clog it drops to the 8 to 10GPM range in four days, this is when I change the filter. Shower water pressure at this point is almost non existant if the heat pump is running. The glass tube on the flowmeter has to be taken apart and cleaned about once a month because the film of clay makes it unreadable.

[yorkguy]

Okay, thanks for the info. I wanted to make sure you weren't using more water than needed for the heat pump. It sounds like there is not much I can tell you to do differently that will prevent the problem. A well driller might have a better idea though if you haven't tried to ask already. If it were something that could be corrected it would save you a pile of money vs changing to closed loop.

[cdhand]

M

[dforster2]

I am not a contractor nor do I know that much about these systems other than having one installed. I can just tell you what they did on mine and that it seems to work very good. I'm also very fascinated with the whole system so I continue to try to learn more about them.

I had 4-300' wells for my closed loop 7 ton system. So the 600' seem to jive pretty good with your loop sizing anyway. I'm not sure but I think i recall the contractor telling me that more holes is slightly more efficient than 1 large hole, not sure why. Logic would tell me that since the earth temp is constant below 6 or 10' it doesn't matter how deep you go as long as it is more than 100' or so. The reason for more holes might be that it's easier to manage for the loop installers and you'd have less joints, etc. And in my layout at least they dug a huge trench so the main manifold connecting the wells together is about 5-10' deep, so there is only one penetration through the surface for all the wells. Seems to me like you would want as little loop as possible in that range above 10'.

If you have an existing pond you could ask about a closed pond loop. That was a cheaper option for us but the contractor recommended the closed loop just becuase the pond loops are a little less stable and the pond has to be at least 12 or 14' deep.

[taswank]

You have me confused, how could more wells mean less joints? One well would mean just two connections at the top. I also don't know what you mean by only one penetration through the surface for all the wells? I have heard that more wells means less pressure drop, which means a slightly smaller circulating pump but I could live with a little larger pump do minimize underground joints and dig a lot shorter trench.

[acwizard]

By having more groundloops instead of one the energy that is extracted or dumped back into the earth has a lower effect on raising or lowering the earth's temperature. This results in higher heat pump efficiency.

[dforster2]

You have me confused, how could more wells mean less joints? One well would mean just two connections at the top. I also don't know what you mean by only one penetration through the surface for all the wells? I have heard that more wells means less pressure drop, which means a slightly smaller circulating pump but I could live with a little larger pump do minimize underground joints and dig a lot shorter trench.

Well I am just speculating. But it makes sense that with shorter lengths of pipe (more shorter wells) they don't have to splice. The rolls are about 500' I think which would cover up to a 250' well w/o any splices inside the well itself.

But wait, I think I remember seeing that they spliced a U shape fitting onto the bottom. So scratch that idea. I guess you could have a 500' well w/o splicing in between then.

[dforster2]

By having more groundloops instead of one the energy that is extracted or dumped back into the earth has a lower effect on raising or lowering the earth's temperature. This results in higher heat pump efficiency.

I thought of that too, but then I convinced myself that no matter how many wells you have, you still have the same length of pipe touching the same 58F (or whatever it is) volume of earth. The area around the pipe is the same no matter how many wells there are if you have equivalent length. I'll have to think about that some now..

[marko1]

Loop legnth is a HUGE factor on your energy use/ performance and comfort. My advice to you is to hire someone from the IGSHPA Accredited Installer list in yor area to design it for you based on your needs. THis may be a small cost but a huge advantage. Then hire them to spec the driller what do drill. Also look at installing a no pressure system , it is a great option . ! Then have them log all data and do a test of performance before and after the job is done. That will be a great end result. Remember PA is a HEATING climate, bores should be treated as such. Its a good first question to weed out a non performing design .

[taswank]

I don't know what a "No Pressure System" is, I've tried searching the internet but came up empty. I assumed all were the same, just circulating the coolant through the Heat Pump and then out through the loops to warm back up. I know I don't know much about GeoThermal Systems but I just don't understand how a loop can be spec'ed out any difernetly. 600 ft of loop is 600 ft of loop. I will trust what a professional tells me but I'd like to have an understanding before I hear it. Can anyone tell me, or give me a link to an explanation of how these different types work?

[marko1]

loop length is a heat exchanger, a heat pump takes what water you give it. No 2 loops are alike or perform alike. A design is too complicated to convey or teach easily . You need a qualifie designer and then you will naturally learn as the process goes along and you ask a watch.

[marko1]

go to the international geothermal heat pump association website and poke around. accredited installers

[taswank]

I contacted two different IGSHPA Accredited Installers and had two different opinions. One wants to fill from the top down with a limestone slurry (consistancy of sand). He said with the water mix he is sure it will fill completely with no voids. He says the limestone fill has a better heat transfer rate than the Bentonite Clay mix that is used when filling from the bottom up. The second guy wants to fill from bottom up to assure there are no voids and he says that the heat transfer rate of bentonite is good and has been doing it for years. I read somewhere in the forum that bentonite doesn't have a good transfer rate but I also read pretty much unanamously that they should be filled from bottom up. Is there a different fill other than bentonite that should be used or is the Bentonite acceptable?

[marko1]

Now I understand why u are confused . I think what you need is an hvac installer that is an accredited installer. You are referring to the driller . I always tell the driller what I want because I know what I am installing and what I need From the loop to do the job. Also I know what pumps Imusing and what loop temp I need through the seasons. As long as the match is good and the loop is put in to what I design and it fits the budget and performs everybody is happy.

[taswank]

These are Accredited Installers I spoke to. One seemed to put the decision of how deep to drill on the Driller because he claimed the driller has been doing this for 20 years and he is the expert. I shying away from this guy because I feel he should be dictating these things to the driller. The other Installer wants to fill from the bottom up with Bentonite. He hasn't said how deep yet other that he will do it in two holes, he is waiting until he comes Monday to look over my system and get all the needed specs. I do like this better, I just wondering about the Bentonite fill he likes to use.

[acwizard]

Bentonite is a very common material to fill the holes. It has the ability to transfer energy from the loop to the earth.

[marko1]

It would be neat if we could see there specs

[djastram]

Information on "no pressure system" flow center.

http://www.bdmfginc.com/QT_Brochure.pdf

I have no affiliation with B&D, but I like them alot.
d

[farbeondriven]

Information on "no pressure system" flow center.

http://www.bdmfginc.com/QT_Brochure.pdf

I have no affiliation with B&D, but I like them alot.
d

Ive seen these before and think there a really cool set up. My only thing is bringing the manifold inside and having vlvs. on each loop. I generally like to keep them burried where i dont have to fight to insulate them properly and make the piping look decent.

[tg8826]

The fast answer is to keep the open loop system, plumb in a system that allows for reverse flushing the system (as much piping as practicle) with a water velocity (not GPM) of 5 feet per second for two miinutes with a mixture of your well water and calgon that is gently mixed together. You want the mixture to be a liquid and not a sudzy bubble bath. Do that every 6 months and you should be golden.

I have vast experience in water main work and dealing with debris in lines.

To keep the lines free of sediment, the water velocity needs to be 5 feet per second. This is called the clearing velocity and is used on lines from 2" to 85" in diameter when the utlilty wants to get debris out of the line.

From a GT standpoint, you will have a higher efficiency because of the water volume GPM that will exist.

Regarding the clay, a sediment trap will not work. As a geotechnical engineering technician in my prior life, the particle size and weight of clay and silt particles allow them to stay suspended in a still column of water for days or weeks before settling.

The logisitcs of 5 FPS and the discharge is a differnt matter.

[mstrblstr3]

I don't know what the censored means either. I do have a flowmeter for the system. Florida Heat Pump says it should run at 12GPM. With the 40/60 pressure switch for my well pump, it is set at 12GPM at max pressure but drops to around 10 at min pressure. As the filter starts to clog it drops to the 8 to 10GPM range in four days, this is when I change the filter. Shower water pressure at this point is almost non existant if the heat pump is running. The glass tube on the flowmeter has to be taken apart and cleaned about once a month because the film of clay makes it unreadable.

All the equiptment I've worked on only requires 1 and1/2 gallons per ton.

[mstrblstr3]

Information on "no pressure system" flow center.

http://www.bdmfginc.com/QT_Brochure.pdf

I have no affiliation with B&D, but I like them alot.
d

the no pressure system has a resevoir mounted above the circulating pump where the air can escape from the closed loop system. This eliminates the need for a flush cart when filling a closed loop. The level can be monitored through the sight glass and refilled with a hose if it gets low. WaterFurnace just unveiled their new design and it looks like it will take care or a lot of problem loops where air just seems to never get flushed out and takes out a pump now and then

[mstrblstr3]

These are Accredited Installers I spoke to. One seemed to put the decision of how deep to drill on the Driller because he claimed the driller has been doing this for 20 years and he is the expert. I shying away from this guy because I feel he should be dictating these things to the driller. The other Installer wants to fill from the bottom up with Bentonite. He hasn't said how deep yet other that he will do it in two holes, he is waiting until he comes Monday to look over my system and get all the needed specs. I do like this better, I just wondering about the Bentonite fill he likes to use.

I typically spec. a 150 ft deep well per ton, all connected to a reverse return header grouted form the bottom up with thermally enhanced grout.
My well driller and I are both Internationally Accredited loop installers and he does his best to give me what i spec. but no ground site is the same so he can only do his best with the conditions.
If I have space, I always do a horizontal loop with a backhoe. The results always seem to be better for cheaper, and the variables can be seen with the naked eye. Its hard to tell what is happening with a bore hole hundreds of feet below the surface