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View Full Version : Rhoss aluminium condenser coil o-ring leaks.







laf100
02-06-2017, 11:40 PM
2 R134a Turbocor chillers on the same site, circa 6 years old:

Where the discharge and liquid pipe headers connect onto the aluminium heat exchangers, each fitting/union comprises of 2 x o-rings to effect the gas tight seal. A total of 36 joints (72 o-rings) per chiller - almost every one of them is leaking (badly).

I'm thinking poor pipework alignment at the factory, poor aluminium H/E tolerances or perhaps lack of care during transportation and/or lifting/installation.

Any my experience or insight to this issue hugely appreciated.

As always, thanks to anyone who takes the time to read this plea!

LAF

RANGER1
03-06-2017, 08:07 AM
Do you know what type of "0" ring material?
Could you explain type of joint Or fitting used.

http://www.hdslippers-partners.com/cgi-bin/pdf/Technical_Articles/cloroprene.pdf

laf100
03-06-2017, 08:57 AM
Hi Ranger - they are green rubber/neoprene seal that fit onto a brass "stem" which slides into aluminium hole on the condenser coil.148311483014829

hookster
03-06-2017, 09:56 AM
Hi Ranger - they are green rubber/neoprene seal that fit onto a brass "stem" which slides into aluminium hole on the condenser coil.148311483014829

Green is a HNBR o-ring which is rated as marginal to poor for refrigerant sealing with the new blends of refrigerant but as neoprene would be the correct selection but is not suited to high temperatures they use HNBR on the condenser connections.


Your failure will not be manufacture as it has been in operation for 6 years, more likely leakage is due to the thermal expansion differences between copper and aluminium. Aluminium expands 35% more than the copper and as you are seeing the leak on multiple systems this will be the case.


'Micro Channel' coils are another manufacturer scam to cut production costs and lower refrigerant volumes in systems (this is another topic) The amount of condensers I have replaced in the last two years that have all failed after 5 - 8 years operation has field proven my view that I do not ever recommend micro channel to clients on new equipment.

laf100
03-06-2017, 09:33 PM
Many thanks hookster - whatever the cause of the failure 6 years of operation is clearly unacceptable.

I think the only long term solution could be to either retrofit with copper coils, or leave the failing aluminium ones in situ and pipe across the roof to a remote condenser, if space allows.

RANGER1
03-06-2017, 11:26 PM
If the Parker link is to be trusted, it say's Neoprene, EPDM & HNBR are OK.
Would be interesting to see condition of "0" rings removed because of leak.
Are the deformed, perished, cracked.
If installing new "0" rings ensure everything is cleaned & polished where '0' rings sit & seal.
I would use "0" ring silicone grease as very easy to assemble parts with no damage.
Turbocor we should also remember has no oil in system which is a relatively new thing.
I would use 1 of any of the above '0' ring in one groove & a "KALREZ" "0" ring in the other.
They are very expensive, but maybe worth it, shop around.
'0' ring crush also important to have the correct amount when selecting.
Measure ID of groove & OD of fitting, then correct size section of "0" ring can also be checked or altered if necessary.

laf100
04-06-2017, 08:27 AM
Gosh - I feel a little embarrassed that you have put in more research effort than myself, Ranger!!

However, for the record the old seals were "marginally" cracked/perished but not deformed - to be honest, regrettably I did not examine them as closely as I should have.

We used have used OEM o-rings as replacements, also we did clean the aluminium sealing surfaces and use a light smear of silicon grease to allow reinsertion without any snagging/tearing or stress to the new seals.

It's all gas tight and back online now, but I do fear for the long term service of these chillers. Carrier use a very similar union/connection without issue (as far as I know) on their R410a Auqasnap chillers, but they use "normal" scroll compressors with a lovely old sump and oil!! I wonder if the oil is the key to the effectiveness of the o-ring seals longevity?

LAF

RANGER1
04-06-2017, 09:00 PM
It is also hard to experiment with as in 6 years unit probably would have to be replaced anyway.
They use HNBR on car air con so it cannot be that bad.
All compressor manufacturers use them, but have oil.
When should we have set the stopwatch on repairs you made?

laf100
04-06-2017, 09:17 PM
In an ideal world it would be replaced after another 6 years, however on our books we currently have Hitachi screw chiller over 28 years old, and another site with a Carrier that's over 30 years - premium clientele!!
The Rhoss was run up yesterday, so put a date in your diary Ranger!
Thanks again.