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View Full Version : killing my scroll's continued



ENERGY KNIGHT
20-03-2012, 10:14 PM
im back to trying to get these climacool modular chillers to work on my own (hopefully with the help of you guys) the problem seems to be in the condensers. they are not climacool condensers they are custom built by a company called mamoth. obviously mamoth has left us hanging. they know the problem is in their condenser but will not help remidy the problem. so yesterday I re-piped the end of the condenser. the presure drop is gone witch i think is a good thing but I still can't charge the system right. I had 225psi on the discharge of condenser at 107 deg f witch I think is only 2deg sub cooled on r-22 . I cant get a clear sight glass. the only way I have been able to get good super heat is if I over charge it and open txv all the way. but then my high side is 275psi on a 65 deg day with fans full speed. if I close txv valve I get a clear sight glass but way too low suction presure and way too high superheat like 25 deg. but the high side does also come down I'm confused.

Magoo
21-03-2012, 05:14 AM
What is the suction pressure / temp conditions. Oil cooling could be the major problem killing compressors. there should be an injection port on compressor.
More info would help

ENERGY KNIGHT
21-03-2012, 01:48 PM
the suction line presure and temp varies with how much r-22 I put in and were I have the txv set but when I get down around 10 deg superheat the high side is through the roof like 275 psi on a cool 65deg day and cond. fans are at full speed.when I charge the system so that the high side is normal then the suction pres is like down to 40 psi and like 55-60deg.

aramis
21-03-2012, 02:26 PM
. so yesterday I re-piped the end of the condenser

You should clarify this, does it have a subcooling section you modified or you mean the exit collector?


the presure drop is gone

Normally a condenser with no pressure drop is not condensing well. It could mean that only gas is going through one or more circuits.


if I over charge it and open txv all the way. but then my high side is 275psi on a 65 deg day with fans full speed

If you have high temperature and thermal load in the coldroom this could also be a transient condition. It would also mean your condenser was designed/selected for the system working in other conditions. The scrolls can take it as long as you don’t have high discharge temperature in the compressor.

It is normal that the lower rows of the condenser are close to ambient temperature like 5 to 10%. If you have more rows at ambient temperature THEN you can say you overcharged.

If your condenser is not overcharged and ends up with more than 30°F differential (saturated temperature measuring pressure at the outlet – air in temperature) then you can say your condenser is undersized.

You should measure and post suction pressure concurrently like Magoo asks.

Also make sure that if you stand in front of the condenser sucking air that you don't feel hot air going in. This would mean you have hot air recirculation.


if I close txv valve I get a clear sight glass but way too low suction presure and way too high superheat like 25 deg. but the high side does also come down I'm confused

25°F cannot be considered high superheat.

Post where is the sight glass located and if the liquid line goes above or below the sight glass level. The only place a sight glass is useful is if it is near the TEV, otherwise it may be misleading and make you confused.

Magoo
22-03-2012, 01:31 AM
Is it possible that you have non-condensables in system, 275 psig discharge is 50'C condensing with R22 on a 18'C day.

ENERGY KNIGHT
22-03-2012, 10:11 PM
i now have 215 psi vapor going into top of condenser. I have 200 psi at 101 deg f leaving the bottom of condenser. which is 0 deg subcooling. why 0 ? am I under charged. my pres just before comp. is 66 psi at 48 deg f which is 10 deg superheat thats good right? outside temp today is 60 deg f. evap temp is always 42 deg f. condenser fans running slow at 33hz.

mad fridgie
22-03-2012, 10:30 PM
That looks good.
wetted coil (no excessive SH, good)
Fans controlling. (good)
Subcooling, if it is a free draining cond, then little or no subcooling will occur.
The system seems at a good equilibrium.
Do not compromise discharge pressure for the sake of subcooling.

Magoo
22-03-2012, 11:28 PM
Aim for +35'C condensing temp., for R22. Increase Hertz a fraction on the condenser fans. [190psig /95'F]. Check liquid temperature entering TXvalve, to check pressure loses as a comparison to liquid temp leaving receiver

rmihvacr
29-03-2012, 03:45 PM
Does this condenser have any head pressure regulating devices (I.E. C.R.I.T. valves)?