Walk in Chiller freezer problem

[simomatra]

Hi
New to the forum. So here goes

On the last ship I was on there was a problem with the walk in chiller freezer. Its running on R404a seawater cooled condensors

Problem was unit was freezing the suction line right back to the compressor.

Am i right in assuming that the problem was caused by someone charging with gas and not liquid? or is there a problem with the systems TX valves causing liquid carry over

Thanks in advance
Sam

[Freezeking2000]

Maybe it is just like that. What was your temp and pressure, superheat?

[simomatra]

Thanks freezeking

From memory the pressure were 240 and 20 psi
Super heat not known Condensor was showing what appaered to be a good quarter of an inch of oilly looking substance on the top of the liquid level. At leat three persons wre fiddling with the unit and problem was still there when I left the vessel. Just looking for some reasons Vessel had only the pressure gauges on the compressor for diagnostics

Thanks Sam

[rimek]

404a @ 20psig sat. pressure = -14°F, That'll draw frost 4 sure. What was walk in temp? Not all line frosting indicates liquid floodback. It's dependent upon many factors-ambient humidity, sat. vapor T-P relationship.

[hoshiscotsmanito]

It is common for freezers to frost the suction line back to the compressor. If the compressor itself is frosting then you have a problem. Possibly with the superheat. Adjusting the TXV to obtain proper superheat can solve this.

[k-fridge]

If the compressor itself is frosting then you have a problem.

Not necessarily, it just means that part of the compressor is below freezing. Than can happen with SH well within range.

[simomatra]

Thanks guys for the quick responses

The walk in fridge temp was +10 Deg C and the Freezer was running -13 deg c

The compressor was starting to ice up and the head temperature was coll enough to place the hand on it

As far as I am aware noone adjusted the TX valve due to laek which was found in the freezer only Freon was added

Many thanks for the replies
Sam

[k-fridge]

Originally posted by simomatra
Thanks guys for the quick responses

The walk in fridge temp was +10 Deg C and the Freezer was running -13 deg c

The compressor was starting to ice up and the head temperature was coll enough to place the hand on it

As far as I am aware noone adjusted the TX valve due to laek which was found in the freezer only Freon was added

Many thanks for the replies
Sam

The cool discharge line can be an indication of low superheat which will also cause the suction line icing. You would want to put a superheat thermometer on it and adjust to specs, typically around 6*F for a freezer at the evap and 20-30*F at the compressor.

[simomatra]

Thanks K_fridge

As I tend to be thrown these problems whilst away on the ships I think I will invest in some professional test gear and carry with me. Most ships tend to have little in the way of test gear for the HVAC and fridges semms a forgotten area even with all the new strict rules they don't comply too

Many thanks once again

Merry Christmass to all from down under
Sam