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  1. #1
    Join Date
    Jan 2011
    Location
    Central PA
    Posts
    7

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

    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.

  2. #2
    Join Date
    Jul 2006
    Location
    St.Paul, MN
    Posts
    125
    Quote Originally Posted by taswank View Post
    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?
    Remember, some poor fool has to work on what you install someday, and it might even be you.

  3. #3
    Join Date
    Jul 2006
    Location
    St.Paul, MN
    Posts
    125
    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.
    Remember, some poor fool has to work on what you install someday, and it might even be you.

  4. #4
    Join Date
    Jan 2011
    Location
    Central PA
    Posts
    7
    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.

  5. #5
    Join Date
    Jul 2006
    Location
    St.Paul, MN
    Posts
    125
    Do you have flowmeter so you can see how many gpm you are running?
    I don't understand the censored or what for I did't use bad language or anything can some one explain???
    Last edited by yorkguy; 01-30-2011 at 12:05 AM. Reason: why censored?
    Remember, some poor fool has to work on what you install someday, and it might even be you.

  6. #6
    Join Date
    Jan 2011
    Location
    Central PA
    Posts
    7
    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.

  7. #7
    Join Date
    Jul 2006
    Location
    St.Paul, MN
    Posts
    125
    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.
    Remember, some poor fool has to work on what you install someday, and it might even be you.

  8. #8
    Join Date
    Jul 2010
    Posts
    42
    M

  9. #9
    Join Date
    Jan 2010
    Posts
    55
    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.

  10. #10
    Join Date
    Jan 2011
    Location
    Central PA
    Posts
    7
    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.

  11. #11
    Join Date
    Apr 2010
    Location
    southern california
    Posts
    535
    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.

  12. #12
    Join Date
    Jan 2010
    Posts
    55
    Quote Originally Posted by taswank View Post
    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.

  13. #13
    Join Date
    Jan 2010
    Posts
    55
    Quote Originally Posted by acwizard View Post
    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..

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