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Føroyar
11-06-2016, 10:17 AM
hi
I have two Danfoss Optyma plus units, running on 404a, started them up last week after they were pressuretested with nitrogen and vacuumed for several days as i was called to another job, they are supposed to keep two rooms at -5 Celcius, I do not have much experiance with other than NH3.
One unit is running perfekt -12 suction when temperature is -5 celcius, but the other unit has a very low suction pressure at -25, I have suspected the TXV TES2 valve to be faulty, took the magnetic valve out and checked it for oil it was perfectly clean, was having vacuum pump on and there was vacuum back throught the TXV
Could it be overcharged, I have put 7,25 kilos on the one that is running perfect and 7 kilos on the other, but the sight glass is looking good on both, with no bubbles.

chemi-cool
11-06-2016, 10:47 AM
There is a restriction somewhere, have it checked.

Glenn Moore
11-06-2016, 04:52 PM
Which model unit is it ? And what size orifice is in the TES 2 valve ?

RANGER1
11-06-2016, 10:09 PM
When running check for liquid line temperature differences across filter drier , any valves like solenoids that could cause restrictions. If colder means pressure drop or restriction,
if OK I'm thinking pump down unit again & check strainer, orifice & power element on TX valve.
When inlet to valve flare nut is undone to expose orifice, orifice & strainer should be checked for any obvious signs of debris, clean parts before assembly.
If OK insert it back in valve & check that power element will not allow it to go in all the way unless you use some small force to inset it.
That could determine if power element has any gas charge left in it to open valve, if not new valve.

http://www.ra.danfoss.com/TechnicalInfo/Approvals/Files/RAPIDFiles/01/Asset/T2-Ver/T2-Ver.10.04.27-.02-2D-L.swf

Check on bottom of TX valve link for how valve works exactly & has some animation for different loads if you slide low to high load.

Føroyar
13-06-2016, 08:52 PM
Thanks for fast replys

I was at the site today, I could not feel any temperature difference around the filter or at the pipes I can access, can´t access the TXV today.

One more problem maybe this is the original problem, the condenser fan is running all the time, also when compressor not running, maybe build up of 404a in condenser ?
I have not had access to the TES2 with a 0,6 orifice but as soon as I get access I will try to take the orifice out and check the valve and orifice.

RANGER1
13-06-2016, 09:16 PM
Thanks for fast replys

I was at the site today, I could not feel any temperature difference around the filter or at the pipes I can access, can´t access the TXV today.

One more problem maybe this is the original problem, the condenser fan is running all the time, also when compressor not running, maybe build up of 404a in condenser ?
I have not had access to the TES2 with a 0,6 orifice but as soon as I get access I will try to take the orifice out and check the valve and orifice.

If discharge pressure to low TX valve may not be able to function properly.
If you cannot access TX valve, fan could be looked at or checked by somehow turning on/off to regulate discharge pressure.
What is the current discharge pressure?