I built a new building and went with geothermal. The contractor turned on the air handlers in June. The system has 6 air handlers totaling 20 tons and has 25 grouted 200' bore holes. The system is a single pressurized ethylene glycol loop with 5 circuits. We are able to hear air flowing in loop piping any time you get close to the loop pumps. The installer has been out 7 times now to re-flush the loops. The first couple of times he just spent about 3 hours flushing the loops, but the last few times he has spent between 8 and 9 hours flushing. The loop psi dose drop about 3 psi between flushes. I do know that I’m one of the largest installs that company has done. I have asked a few times about installing an air eliminator on the highest heat pump, but he says they lead to more issues than they solve. The list of excuses about the air in the system is to long to post. I'm thinking he needs to do a loop by loop flush (I think the last time that was done was in June). What are your thoughts on air eliminators? Is there anything else I should talk to him about?
sounds like he needs a bigger to pump to flush with....possibly bigger purge ports. Is he flushing both directions through the loop?
I talked to him on the phone today after reading your comments. He's looking at air eliminators. He also said he had not been doing a loop by loop flush or revers flushing so he did not shut off our a/c thinking it would shut down our production lines. I asked about his flush cart. It's 1.5” hoses with 1.5” ports and a 1.5 hp pump. He's coming out next week. We are going to switch over to backup heat for the day he can do what ever he needs to do. He says he plan on 8 to 12 hours. Thanks for your replies they were right on with the stuff I have found on the web.
there is no way he can purge 25 loops at once with a 1.5 HP pump. Each 1" loop needs 6 gpm to properly flush ....6 * 25 = 150 GPM to purge . No sense even coming out if he can't push the required flow
It is a rookie mistake to put the header outside buried and not being able to control loops or group of loops individually from the inside, so they can be purged easily. If done correctly, you actually use the circulation pump(s) to purge out the loop field. Just to make sure, do you have w-w heat pumps with air handlers, or water to air? Then you need either an air eliminator for pressurized systems, or a non-pressurized flow center, since gases will continue to participate out of the water, forming bubbles.
We have an outdoor vault (it wold make a nice man cave) that has the manifolds and the purging taps. I sat the installer down and talked to him and he admits he was afraid of doing the loop by loop flush. He did not want to shut down our production run (food) $$$. This time we switched 3 units to backup heat, turned one off, and left the other 2 on cooling after he installed 2 air separators. With only having the 2 units on he flushed away. It's been about 18 hours from the time he finished and everything looks good so far and the pumps are almost whisper quiet. He wants me to do daily psi checks for a couple weeks and call him if the psi drops more than 10 psi. All of our our air handlers are water to air, pressurized, and just now got 2 air separators.
Sorry Doc, I could not disagree more with this statement. With hundreds of installs, all buried headers, we have only had one problem with a loop. It turns out the header was not made properly at the factory and one of the fusions cracked. Because we bury the headers we only have the supply and return headers in the mechanical room, making a very tidy install. One of our competitors tells his prospects that bringing the loops inside allows him to "turn off" a loop if a problem arises. This would only hold true in the summer when fewer BTU's are required for cooling, but come winter... the entire loop will be required making digging up the loop a must.
For the record, KWH pipe is a manufacturing client of mine. I helped them sort out a general commercial vault design. Uponor has now bought out KWH and they are sending me a 6-ton residential vault to try out on a site. I'll definitely keep folks posted.
I would be interested to see what a 6-ton resi vault would look like and the cost. I went on the website but not much info.
