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09-09-2011, 10:03 PM #1
install on 3 splits piping problem suspected
ok so ill start from the top explaining the equipment i took out and how it was set up
1 5 ton system it was a 20 year old york unit suction line size 1 3/8 liquid line size 5/8. the line set is about 150 ft long and the system i guess ran good for all that time minus the usual repairs
2 4 ton systems same setup but 1 1/8 suction and 1/2 in liquid.
so now my question i did as the boss told me and installed the 3 splits i did not change the liquid lines but i did change the suction line riser inside about 20 ft up to 7/8 and kept suction lines the same from where they went horizontal. i put in oil traps again and i did flush the lines with rx 11 .
anyways i started up the systems after evacuating balance my charge to 8 degrees subcool per mfg then checked superheat i had 8 degrees subcool and 36 superheat pressures 125/330 i added 410 a to systems and got superheat to 15 on all subcool was about 18 at that point so all should be doing ok not perfect but ok
went inside to check split on units they are all at 14 degrees.
I checked back to the chart from mfg and found according to that i was undercharged
71 degree indoor wet bulb temp
100 degree outdoor at c/u
chart says i should run 140/425
compressors scream at that pressure so i recovered some refigerant after i brought one to that level but it did cool better 17 degree td
electronic sight glass says liquid line not full
should i run all new line sets that what i think but thought i would throw this out there
09-09-2011, 10:23 PM #2
I think your suction line is to big.I'm not tolerating Political Correctness anymore, from now on it's tell it like it is.
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09-10-2011, 03:16 AM #3Regular Guest
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- Apr 2010
- southern california
Do not concern yourself with the sightglass on a 410 system.
09-10-2011, 01:16 PM #4
Where are you reading your superheat and subcooling numbers? Is it a TXV or fixed orifice? With a 150 foot suction line you may have 25 to 30 superheat at the condensing unit. Charge the unit to the subcooling leaving the condensig unit as compared to the chart and thats it. If it seems off from there look for other problems IE air flow and such.
09-13-2011, 06:38 AM #5
If you look at long line specs for the new units I believe you will find that 3/8 is max liquid line and you may need a solenoid at coil to prevent slugging at startup.