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Leaky closed horizontal loop?

Discussion in 'Vertical and Horizontal Loops' started by Laura, Aug 30, 2012.

  1. Laura

    Laura New Member

    We are looking at buying a house (my first panicked rant is on another thread) that has a potential problem with the geo loop. I am a mechanical engineer, but I don't have any experience with residential or these geothermal systems. I am somewhat familiar with heat pumps. Just enough knowledge to be a pain in the ass.

    So we've had two contractors look at this geothermal system in a house were are hoping to buy. Both confirm that there is air in the geo loop. A pressure gauge attached on (assuming) the suction line at the heat pump pulls a vaccum. First guy said it is probably not a leak but bad maintenance. He said if the loop is leaking we should replace it. Second guy looks at the pipe from the heat pump to flow station, points out that one is slightly compressed, and said that there is definitely a leak. Prior homeowner tells us they had it serviced two years ago and "bled" the air out of it. I assume they mean purge, but in this neck of the woods you never know who someone is going to get to work on stuff. This is Montana, not a huge market and lots of fly by nighters. This second contractor also said a leak is no big deal, just put an unpressurized flow center in.

    The contractor that installed it has a reputation of having had hit and miss installers, some were good, some were bad. We have no documentation on the installation.

    I am not sure how far to push the sellers to diagnose and repair this. The non-pressurized system strikes me as a bandaid, leaving the system to possibly continue to degrade ultimately needs replacement anywhere. If it was poor installation, or poor materials, that could be real. I also don't want a bucket of methanol in my house that the station would require. I also don't like the idea of knowing that I'm dumping methanol into the ground, above a spring which we will be using to irrigate.

    Most of the information on this site seems to indicate that loop leaks are rare. The second guy told me that they all leak. That could be back to the fly-by-night aspect of this market here, many installers came and went and poor installation could have been a problem with many early systems.

    Does it seem unreasonable to expect a geo loop to not leak? As I've alluded to, I'm not keen on buying a house with a known failure, even if it often happens. I can still run away! It's pretty straightforward to put money into escrow for repairs, but I'm concerned about one contractor saying a leak is fine, if I am not in agreement nor comfortable with it. Is there criteria that says a certain amount of leaking is "OK" and we'll be stuck with it? Or is there industry guidance that supports my opinion, that any leak is a failure. I don't care of 1000 of these were put in bad and leak, I had an expectation in the offer that the system was intact. Thanks.

    Time is of the essence here so please respond if you have any inclination to do so.

    Laura
  2. Palace GeoThermal

    Palace GeoThermal Active Member Forum Leader

    to answer your question , no.

    It is pretty easy to tell if the loop is leaking, just flush the loop to get all of the air out and then pressurize it.

    Run the pressure up to 50 PSI, hold it there for an hour, then drop pressure to around 30 PSI.

    After a day if the pressure has dropped below what you left it at, then you have a leak.

    Most leaks are very slow drips inside of the mechanical room where all the fittings and clamps are. You need to look closely at the fittings for any sign of moisture. Many times the leak is so slow that it will never drip.
    Last edited: Aug 31, 2012
  3. Howard Ek

    Howard Ek Member

    I am a mechanical engineer. I have put in close to a hundred geo systems. Once we found out about the non-pressurized systems, I would never go back to the pressurized systems!!!!:)
  4. Jamesck

    Jamesck Member

    Howard, I currently have a pressurized system. What is the procedure to go to non pressurized if needed? I think everything is fine, but the pressure dropped a little after the first year. I think there is a flow center that you take the lid off of to add liquid, but have not seen them for a while.
  5. Howard Ek

    Howard Ek Member

    Phoenix Flow Centers

    GT Flow Centers, without pumps. Then you just add the pumps that you have on your existing pump package.
  6. Jamesck

    Jamesck Member

    Laura, that is a great question! You posted it in the right place and I am sure you will get great answers. I wish that I had more experience with the loop side of this type of system.
    I did not get to be involved with mine because of conflicting obligations. From what I have heard if they are installed properly there is a very good chance of not having leaks. The piping material is very strong and the fusion joints are too.
    Now, I can't wait to see some of the responses to your issue. Good luck!
  7. Calladrilling

    Calladrilling Member Forum Leader

    Loop conditioner

    Personally, we never used it. I have known of a few jobs that have had it installed on small leaks and it seemed to work just fine. It is a cheap and easy fix if the leak is small.
    First do as Palace recommended above ( purge,pressurize, and judge size of leak).
    Do a google search for "loop conditioner" and you see the products for yourself and make you own opinions.
  8. AMI Contracting

    AMI Contracting Clever paste up by a player I coached Forum Leader

    I suggest tightening hose clamps, bumbing the pressure and wait and see. 99% of the leaks we see are from hose kit.
    j
  9. Laura

    Laura New Member

    Thanks Everyone- The owner reports that they bled (probably meant purged) the system 2 years ago. So it could be that they did it wrong or indeed there is a leak. The mechanical room is clean, not a single sign of leaks. I finally got copies of the installation plans, and apparently it is a slinky system in 5' trenches, which as I understand means it could be 3' deep at the top of the slinky (1' bedding, slinky 1' tall when laid out). The field is right in front of a walkout basement entrance, which I believe has been driven on (and will be again) to get furniture in and out of the space. Any issues with this? Not just potential in the past, but for us to plan our own use of the space.

    I called GT and talked with a guy there, and he had a lot of good points, especially that the antifreeze container isn't open to the air and thus we won't have methanol evaporating in the house. His point about reducing the operating pressure of the loop piping system (by eliminating the precharge) was also interesting for preventing future leaks.

    One odd thing he said was that many people switch to propylene. My experience is between ethylene and propylene, and propylene usually requires a different coil (here it would be the geo loop) because of the reduced heat transfer properties and also larger pumps due to the increased viscosity. But that's compared to ethylene, perhaps the switch to propylene from methanol is more comparable? Have any of you contractors done this and had the ability to follow up on performance, either through call backs, lack of call backs, or inspecting the system (temps, etc)?

    Thanks so much folks, I look forward to getting the house and actually learning more about these systems! Keeping my fingers crossed!
  10. AMI Contracting

    AMI Contracting Clever paste up by a player I coached Forum Leader

    1) Probably is a leak as mentioned before it might take a cup of water to drop pressure in a 5 ton 30 PSI (as water doesn't compress). So no visible puddling is expected. Some have used rice paper or equiv. in suspect areas to try to detect. Suffice it to say a cup or two over two years would likely go undetected. You are more likely to have greater puddling from condensate drips.

    2) There are horizontal and vertical slinkies. A horizontal would be a constant 5' (like a spirograph drawing). Verticals are relatively uncommon, but if they had an average depth of 5 feet they would be (depending on pitch) perhaps 6 feet deepest and 4 feet shallowest.

    3) Drive away. Shouldn't matter.

    4)I don't know what a "precharge is". If point is to eliminate leak by removing pressure, the leak will do it for you and eventually even a leaking nonpress system may need the level bumped.

    5) Methyl is a better heat transfer solution than prop. glycol. Many are switching because of the notion that prop. gly. is "greener".
    I don't think that would be my advice.
  11. Laura

    Laura New Member

    So we're buying this house, and got nada from the owners for the probable geothermal leak nor the old heat pump. Oh well. The current electric bills aren't really useful since the daughters have just used it as a vacation home for 5 years. They kept the setpoints high and low while gone.

    So I've got this system now with a ton of air in it. When it operates, the other side of the wall which the pump station/piping is attached just rumbles like crazy - I expect this is the cavitation and air noise transmitting through. Yikes, and that was supposed to be my office! At least it is attached to the closet wall, but hollow core closet doors don't do much. Is it possible that a small amount of air would make that much noise? Or does this more likely indicate a lot of air in the system (and probably more significant leak?).

    Propane would be cheaper to install, but then we wouldn't have AC (useful when we're enveloped in smoke like now and it isn't recommended to open the windows) and propane comes with quite a bit more safety risk. We've seriously considered wood as primary and use the electric strip as emergency/unoccupied only (even add a second one) but we're not really young and the thought of MUST CUT wood is not appealing.

    So we're going to get this thing working and stick with geo. I see three options for us to move forward.. 1) blast in a bunch of water from a garden hose, to pressure test it. I'll dilute the antifreeze but I think that will be taken care of in the next step. 2) Flush the system and just see what it does over the winter. This would be step 2 if step one indicates no leak. 3) Install a non-pressurized pump station. This would be step 2 if step 1 shows a leak. I wonder in the back of my head if we end up doing option #2, will we need to do it again in two years thus potentially making option #3 better for long term cost?

    I've got a proposal to do the pump station, around $1900. I'm inclined to just do that because if we have so much air in the system we must certainly have some sort of leak.

    My question is this: is it even worth it to do a leak test? If not, which option (2 or 3) do you recommend? Please keep in mind this is a new house to use, so we’d really rather keep our costs down if possible, but don’t want to invest well into the system.
  12. Mark Custis

    Mark Custis Active Member Forum Leader

    Glad you got the house.

    When one buys previously enjoyed stuff, it is usually on an as is basis. I do not think that I would buy a boat if all I could see is lines going into the water. You can see the boat, that is a good thing.

    It may have a leak, but so what, if you see the boat and it has a leak, make sure the bilge pump works and go find the leak. Find the leak, fix it and enjoy the boat you got a deal on. I might keep PFDs current and at hand.

    I live with lake Erie as my back yard, so I will add that Personal Flotation Devices, (life jackets), are standard equipment where I live. We all have them and take them with us when we go out to the backyard.

    When I used to teach folks how to swim, a very long time ago, the first thing I taught was not to panic. If you panic in Lake Erie we will find you when your body washes ashore.

    I think you should pretend to think I am teaching you to swim.

    Do not panic.

    Evaluate what you know own.

    Make a mental or written, since you are not IN the Lake, list of what you need to have happen to see the Browns beat the Bills on Sunday.

    When you have that list please send it to Cleveland.

    You need to measure what you think is going on wright or wrong. Make the list.

    The list will allow you to rank priorities.

    If your loops have a small leak, then have them purged and topped off. While the guy is there have them install a pressure gauge so that you can SEE what is going on with the system.

    I treat my customers money like it was my money and look to treat problems with the least expensive cure first. Most of the folks here do that too.

    If you need to calm down or want an ear, try 440.223.0840.

    Mark
  13. AMI Contracting

    AMI Contracting Clever paste up by a player I coached Forum Leader

    The very first thing I would do would be to get geo pro 2 to add water to the loops properly to avoid introducing more air.
    You might find it works fine after that.
    Low solution on a 20 year old in and of itself does not alarm me. We need to begin to build a history from which we can make informed decisions.
    j
  14. docjenser

    docjenser Active Member Forum Leader

    Reading through your thread I am not sure how they could diagnose a leak. Air in the system? They did not pressurize it and pressure tested it!
    Every pressurized system will produce air bubbles. There are gases dissolved in the water (remember the O2 in H2O) which participate out when the pipe undergoes pressure changes due to the temperature changes between heating and cooling. That is inherent with pressurized systems. That is why your second guy think they are all leaking, but they are not, they just form air bubbles.
    Your first guy noticed a vacuum, another indication that that you do not have a leak, otherwise the pressure would equalize and not be a vacuum. HDPE expand with increased water temperature more than water, thus creating a negative pressure if not properly pressurized.

    All those things go away with a non-pressurized flow center. Put it in, chances are that you do not have a leak and it will cure all your issues.
  15. AMI Contracting

    AMI Contracting Clever paste up by a player I coached Forum Leader

    before changing flow centers, just get some pressure in there.
  16. TimF

    TimF Member

    Low Center leaking at "hand tighten only" connector

    Laura,
    Looks like good advice here and I thought I would pass this on as my recent experience shows how a very small leak on my 1 year old system can give the results you are seeing albeit you don't seem to have a leak inside your house. I just recently switched my geo from cooling to heating mode. When the HP came on I noticed I could hear air in my flow center. I opened the lid and the QT flow center was almost empty (only had 14" of possible 32" standing volume...almost empty when the HP was running...just froth at the bottom). I was astonished as that had not been the case ealier this spring...it was within 2-3" of the bottom of the flow center lid threads. I suspect my reaction was much like yours....what now! I added 2 gallons at a time...twice over the course of a week but it seemed as soon as I added the water, the level went back down..but not quite as far down as it was before. Strictly by luck, I happened to notice a small pink droplet on the threads of the QT flow center where the inbound loop pipe connects. It said "hand tighten only" but as it was already to the point I couldn't tighten it more by hand, I put a couple of wrenches on it and turned ever so slightly...it was enough to stop the leak (the glycol was running down the pipe into the flow center...from there it was running under the flow center covers and leaking down the backside of the flow center and running under the wall). I continued to watch the level several times a day but finally after adding another gallon or so, the level has stabilized both at rest and when the flow center pumps are running it only drops a quarter of an inch. It is now 6 days since I last added the water, and with the HP cycling 3-4 times a day, the air bubbles are almost gone...just occasional very small champagne-like bubbles are appearing in the glycol now. After reading this thread, I now know the bubbles are to be expected and not the result of air being added due to a leak....thanks Mark, Joe and Doc..I'm able to sleep nights again!

    Laura, I hope your situation is as easy to resolve......
    Tim
  17. Leaky loop

    Sometimes a pesky minor pressure loss is best corrected by just adding a make up water system. Backcheck valve, maybe a pressure reducer depending on "house" pressure, and a 1/4" line tied to anywhere in the system should keep things maintained. If loss is too much may have to watch antifreeze concentration over a period of time.

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