A properly designed and installed loop should not have to be flushed every year.  Mine has been in service for 5 years and never needed flushing.

A couple of things come to mind:

A leak  in the system that loses pressure and fluid over time

Air being left in the loop while purging.  The air works its way to the loop pumps which then cavitate and produce no flow.

Not enough antifreeze, the loop temp drops, the fluid freezes and pumps can't circulate.

Good Luck and let us know.

Good morning..  I was told that I was operating a 3 ton unit to service a 1700 sq ft home.  The data plate reflects a 36,000 btu of cooling capacity.  It does not have any antifreeze in the loop.  I was not present at any of the appointments that involved flushing the loop.  You can bet I will be at the next one though.  My personal opinion is that air is either not being totally flushed out or is somehow being introduced.  I have noticed gurgling at the circulator pump before and I figure the pump is cavitating.  I have been searching previous post for advice on instruments or gaging to help me maintain this ground loop myself so as to equip myself with the tools to help me do this just to prevent down time and expense with costly service calls.  I've got to tell you that I am now seeing how important it is to find a contractor that has lots of experiance with this specific and unique technology.  I was sold on the system as being very efficient and maintenance free.  I am now experiencing that any advantage I have gotten has been spoiled by the ongoing troubles.  In my case it has not been fire and forget, going on many years now.  Sorry to vent.  At this point I am pretty sure as to the problem and that is air in the ground loop.  My question would be how to get a bullet proof seal on my ground loop?  I just gotta find that leak.  Got to spend away a little bit more of that advantage to fix the problem.  Thanks to all for the replies and wish me luck.  Joe

Oaklahoma is the birthplace of the ground source heat pump industry. Go to IGSHPA.okstate.edu and look for the accredited installer list. Call a few in your area and tell them your problems

Oklahoma not Oaklahoma.

Have an accredited installer come out to diagnose and service.

 

I believe that ground loops are warrantied for 50 years... it would be interesting to see how this warranty is supported. 

The pipe is warrantied by the manufacturer for 50 years.  If the installer left a leak then the 50 years  doesn't apply

My problem was that the loop was not flushed the proper way.  There are detailed instructions with the circulator pumps I had installed.  They have 3 way valves on them that allow whole system flush and or loop flush etc.  My well guy and I went through the whole process as per instructions and we did it with a 1/2 hp pump for 2100 ' of ground loop.  There is a lot of trapped air that is in the system.  Make sure you spend the proper time and flush it according to instructions.  Good Luck.

One note that came up when they flushed my loops (we have three separate systems).

The grundfus pumps have a screw in the center of the pump itself. After the entire loop was flushed, (and the other two configurations of the pump center valves), I was told to make sure that I loosen the screw in the center of the pump for a few seconds to relieve any air that might get hung-up in the pump itself (with the pump running). Sure enough, each pump shot some air out on doing this, when we bled them. The screw should be tightened back up afterwards.

Dewayne, that unit that you mentioned previously to boost line pressure? That is done by hand, right? just adding water to the tube that is part of it? So, to increase the loop pressure, we can insert the P/T fitting, add water to that hand-pump, and bring up the pressure a few pounds? Does that require a lot of water/refils, typically?

The reason I ask is that I am running between 35 and 45psi on all three loops at the moment, and it was recommended that the loop pressure be a little higher (in the 55-70 range for winter). I'd rather not get the flush cart brought back in (they charge me rental for the cart and Time/Materials, mileage, etc), so am wondering if adjusting loop pressure via the P/T points on each unit is reasonably DIY with the tool you use..... I don't see any loop leak or drop in pressure at the moment, but assume that as seasonal changes hit, the first summer with the loops will reduce pressure as the tubes expand, dropping me pretty low. Its probably a one-time / limited time activity, but something that I think we need to be aware of.

As in some other threads, it seems like geothermal isn't quite as set/leave as one would expect, at least in the first months/year(s). I ended up purchasing the temp probes, water pressure probes, P/T to garden hose connector and likely will get the Hand-pump that you mentioned.

A 1/2 hp pump is pretty small.   We have a 2 hp pump that we flush with and sometimes we hook two in series which gives us an effective 4 hp.

Daniel, the small hand pump operates the way that you posted.

However, I wouldn't worry about boosting your pressure. There is nothing magical about 55 lbs. Your system will not work any better at 55 than 35. Mine works just fine at 22 lbs.

The hand pump costs about $500 if I remember right.

My recommendation would be to use your P/T to garden hose connector to keep the pressure as high as your house pressure will take it if you really want to keep the pressure up.

What confuses me is why an air vent isn't a standard installation feature of every closed loop GSHP.

For example, at the highest point for each of my GSHP units, I have an air vent connected to the loop.  I.e., this is the model I'm using:

http://www.spirotherm.com/docs/brochures/Top-2A.pdf


And a diagram of my loop plumbing is here: http://welserver.com/WEL0043 .

It would seem to me that use of an item like an air vent completely eliminates, over time, any residual air left in the loop after purging is done.  And any small amounts of air that works its way into the loop.

Best regards,

Bill

I agree this should be standard!  My well guys and I discussed this over and over.  As far as pump hp, yes you should use the strongest available to flush your loops, I was just saying we did mine sucessfully with a 1/2 hp pump.  It can be done but it probably took us a lot longer.  We didn't have access to a flush cart so we used 2 hoses and a garbage pail filled half with water.   About an hour into it when we thought we had all the air out pockets of air still came out.  All in all, we flushed my loops for about an hour and a half.

I hope you did in fact purge all the air.

I look to Dewayne to confirm my opinion that absent sufficient flow to dislodge air bubbles , it doesn't matter how long one runs an underpowered purge pump - air pockets will still remain. It is a matter of flow velocity overcoming buoyancy. I'd expect a properly powerful purge pump to get it don in just a few minutes - sufficient time to get all loop water up to steady state speed plus time to circulate the total loop volume through the pump and open barrel.

Bill - I'd bet it is a case of cost, vent reliability, potential for it to leak. Once air is all out of a system and it is reasonably pressurized, air should never again be a problem - positive pressure prevents it.

This is true.

IGSHPA  recommends a velocity of 2 feet per second to ensure air removal from geothermal loops.

In a 1" pipe this requires 5 gpm.  If you have four 1" loops in a parallel header, then you need to move 20 gpm.

1.25" requires 9 gpm to achieve 2 fps.

1.5"  requires 12 gpm to achieve 2 fps.

2" requires 19 gpm to achieve 2 fps.