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HI. I`m fairly new to this.but does any one know what the Crankcase PRV is supposed to set at ? and if not set correctly would it cause compressor to ice up on the end when system is going thru defrost cycle. This is for a 5 horse power copeland hermatic compressor used for a reach in grocery store freezer display. 404A *****
the way u need to set it up is to use your gauges and put about 100psig into the suction line and adjust valve until u get compressor to RLA amps
why is my suction line freezing up and compressor sweating when it goes into hot gas defrost? I thought it was because the PRV was not set right
Have a read up on CPR vavles here http://www.parker.com/portal/site/PA...RCRD&stpoint=B
Quote:
Originally Posted by jakb21599
You need to understand what is does first.
There are a few pressure control valves that can be
fitted to the suction but they do different
things for different aplications.
There are crankcase pressure regulators (CPR) and then
there are evaporator pressure regluators (EPR), to name two.
Do not confuse the two..
The CPR protects the compressor from too much suction pressure
Some systems with multiple evaporators and comps use them to
stop the suction pressure getting too high. It is basicaly to protect
the comp in extreme situations like defrost and startup.
The EPR regulates the pressure inside the evap purly
for temp control in the evap itself.
Nether are designed to prevent liquid but both will affect pressures
and therfore temps inside the suction and back to the comp.
You need to find why your suction is freezing. Do not think that a
freezing suction automatically means liquid. It can mean the suction
is below freezing and that will happen with low temp and some medium
temp systems. Remember that the evap temp of a 404 freezer will be
about -35 degC ( - 30 degF in your money ) so the suction will freeze
up with just suction vapour returning.
All the best
taz
.
thanks for your help guys
you have liquid coming back
Suction line freezing and compressor sweating does not indicate liquid flood back.
What is the suction superheat?
Semi Hermetic Compressors can show white frost all over the compressor motor area, up to close to the heads, without liquid coming back.
Determine suction superheat, which should be 5 deg C minimum.
if hes got frosting after the cpr during defrost superheat of tx has nothing to do with it.
5 deg c superheat in low temp system lol
jakb21599,
Frosting on the suction after the Crankcase Pressure Reg on hot gas defrost is normal,i have seen it a on all the hot gas defrost systems i installed,,,it's normal,,,,set the C/P/Reg at compressor full load amps,,,ignore the pressures.
Lawrie