R404A system !

[wallerboy76]

Hi fellow technicians,

I recently replaced a Copeland (RS97C- CAV-251) 1 hp/220volts/51LRA/1ph fecip. compressor using 24 P0E oil on a stand up freezer.

After installing new compressor(1HP/220volts/29LRA/1ph/recip.)it would start with a low charge, then we will charge till sight glass is full & run, pulling down the temperature fine but once condenser shots off either reaching temp. or on timer, compressors does not come back on.

Now my theory is that the system needs a solenoid valve(there was no SV) but my confusion is how did the unit work previously for 8 yeard without SV.

Thanks in advance for the replies.

wallerboy76

[Gary]

Hi fellow technicians,

I recently replaced a Copeland (RS97C- CAV-251) 1 hp/220volts/51LRA/1ph fecip. compressor using 24 P0E oil on a stand up freezer.

After installing new compressor(1HP/220volts/29LRA/1ph/recip.)it would start with a low charge, then we will charge till sight glass is full & run, pulling down the temperature fine but once condenser shots off either reaching temp. or on timer, compressors does not come back on.


So... the compressor ran one time, then shut off... and has not run since then?

[wallerboy76]

HI again,
Th compressor would start & run when ever you start it with little charge in the system. I tried this a few times.

In your experience & knowledge what do you think are all the possible reasons why this might happen, taking in to account the infor I gave earlier ?

[wallerboy76]

The compressor would start & run whenever it has little charge (5psig on off cycle) but once you charge the system till the sight glass full as was the case previously it wouldn't come back on.

In your experience/knowledge any of you guys can tell me why the system wouldn't work as it did b4 please write ? Is there something I'm missing please let me know ?

[chemi-cool]

If the system did not have a SV, why change it?
Adding SV will make any differences on how the system start or run.

If it doesn't come in when temp is rising, check the differential temp in the temp controller or the differential pressure in the pressure control..

[wallerboy76]

Thanks for the response,
Hmmm I don't quite follow Chemi-cool do you mean the temp. of the compressor
but I did by-pass the pressure control & temp. control...

could it be the difference in the LRA in the new comp.(altho after calculating the total pulling amps this shoould not happen)

[monkey spanners]

Has it got the correct start relay and capacitors for the new compressor, or is it still using the old ones?

Sounds like the new compressor hasn't got enough torque to start it once the system is charged, putting in a solenoid valve will not help as the high side will still be under pressure, so it will still be trying to start under a load.

Unless the new compressor is the same model as the old one it could need a different way of being wired up, it would be worth checking it is wired correctly.

[tonyelian]

hi
1-u should recheck ur electrical connections it may ur comp ran on start windings
2-there is a restriction
3=after u turn off did the pressure equalize after while
4 can u check ur condensing temp&pressure ur suction temp&pressure
more info more help

[wallerboy76]

Thanks to all 4d comments it was most helpful, especially Monkey Spanners ! I got the system to work.

Warm regards

76

[lowcool]

hoped you tipped his scales