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Hi!
Old unit history: 18 y.o. R-22 Trane HP 10 SEER unit had a connector go out in Jan 2010 & then the compressor in the Summer; no history of leaks or other issues.
Looking at system replacement - recommending Carrier Comfort 15 SEER Puron (25HCC) HP System w/ variable speed air handler (FV4C).
The issue concerns the copper lines connecting the outside-inside (split) units and the potential of acid contamination.
The local Carrier dealers have different recommendations: some want to replace the copper lines; the others claims that proper flushing will do the job.
Of course, new lines would be the optimal choice, but...
Assuming the flush/vacuum procedure is done correctly, is that a reasonable option to be considered?
If the flush is not adequate, what is the liklihood that the type of problem that may be involved with re-using the existing lines would present in the first year (typical labor warranty period)?
Thanks for your advice!
Freeman
 

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I would try and run new copper whenever possible. Poe oil is acid based and very sensitive to moisture. The supply houses and distributors will tell you different options but I am here to tell you that I have worked with 404a for almost 10 years and when moisture is present it will eat copper, rubber, shredder stems, etc. The only time I would flush is when I absolutely positively could not run new line set, condos etc. I personally do not understand why the 410a units do not have service valves instead of shredders because of the higher pressures and the possibility of leaks. Anyway hope this helps!
 

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The supply houses and distributors will tell you different options but I am here to tell you that I have worked with 404a for almost 10 years and when moisture is present it will eat copper, rubber, shredder stems, etc.
 

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repj2y
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Flushing

I would agree with the other comments ! But; I would install a flared
liquid line filter/drier. Installed that in the line-set outside. I've received
alot of feed-back from various sources, on; installing that near the
Air Handler ! My total concern is the scale in the original line set from
the person who brazed it on installation ! Not using nitrogen or another
inert gas while brazing. The new blends including 404A & 410A along with the oil blends are still cleaning the old line sets. I've found alot
of new customers with restrictions on year old equipment ! Had to
clean orifices and TXV's. I would changed out the drier again in
a couple of months. Of course; inform your customer of the additional
cost. You'll keep that customer all the time !
 
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