Help: Geo Thermal flowcenter goes bad every 6 years...flowcenter leakage issue
We built our custom log home in 2002, went Geo Thermal closed loop.
Here is our system in basement:
(the image has mark-up as 4-5 people on my street desire Geo Thermal to save $$ due to bad winter, so I was informing them how the system works).
Overall I love my system, however Geo Thermal flowcenter goes bad every 6 years...and it's only got a 5 year warranty.
Back in 2008 I replaced the complete flow center, one of the pumps went bad and it seemed logical to replace the whole flow center, knowing in future if a single pump went bad I'd have good "partially used" one in the ready.
You can see that replacement installed here, Mar 15, 2008
5-6 weeks ago I heard some cavitation in the RH side pump, seems there was a very slow leakage that is/was happening, you can see the dried residual i these pictures:
I called my original installer, he added more fluid, and some "stop-leak" like fluid that hopefully may stop the leak, it's not working.
I block out his face for privacy.
a) what's up with these flow centers going "bad" every 6 years? Does not install confidence in me to recommend them to others.
b) I'd like to contact the flow center manuf directly.
Here's closer image of my flowcenter
The leaking has NOT stopped, it's leaked in 5-6 weeks maybe 2 cups?
Orange bucket collects the fluid now, very slight cavitation has just started now.....
Well, literally after I posted the above, went to the thermostat and bad luck, check light is on
Here is how much of the closed loop fluid has leaked from the flowcenter
..............LH pump .................................................. .............RH pump
This is the fluid that is leaking;
Since this is my 2nd flow center that has failed after 6 years of use, what is causing that?
Look at the image here, you can see leakage appears to be by the pump/seal interface, That is my current flowcenter
I did a tear down of the flowcenter used from 2002 - 2008
here it was just before I un-bolted the pump
From engineering 101 DFMEA what are possible failure modes:
- mechanical threads & sealents used
- mechanical fastners/hose clamps
Doing a google search on geothermal ground loop GS-4 mixture, what my installer used
25% GS-4 with distilled water
I find this statement:
a 1998 document
GS4 (Potassium acetate) -
Non toxic, good heat
transfer, high price, non-corrosive with added inhibitors,
low viscosity. Due to its low surface tension, GS4 has
been known to leak through mechanical fittings and
certain thread sealants. A variant of the salt family, it can
be extremely corrosive when exposed to air. CM does not
recommend the use of GS4 with its products due to the
leaking and ultimate corrosion problems associated with
repeated here as well, a 2014 document:
GS4 (POTASSIUM ACETATE):
corrosive (especially if air is present in the
system) and has a very low surface tension,
which causes leaks through most mechanical
fittings. This brine is not recommended for use in
earth loop applications.
Q to experts:
Does this mean that GS-4 is known to cause issues and should be avoided?
I have no idea what that additive is. I've only ever heard of people putting some kind of glycol or methanol in closed loops. I'd bet that's at least part of your issue. The other problem is probably the cavitation. Those pumps won't last long if they are constantly cavitating. Is the only source of your leak right there next to the flow center? It's not possible to re-plumb everything? I could understand if your leak was in the field buried in the ground.....you'd want to try some kind of "stop leak" or just limp along constantly adding liquid. However, this is a leak that is accessible.