replaced cap tube

[Temprite]

Hello everyone.

Recently replaced a cap tube that was restricted on 2 door commercial fridge.

Cap tube size and length was recommended to me by wholesaler that used a selection programme to work out length and bore size.

compressor: electrolux L57TN 444 watts@-5 32 deg ambient 55 deg cond temp.

refrigerant: R22

Recommended length was 1.85metres of 0.9mm which was replaced and drier changed.

unit is working ok but not quite satisfactory.Gas charge could not be weighed in as it had no name plate.Anyway information as follows.

Cabinet temp: 4 deg c
suction: 340 kpa (49psi)
discharge: 1730 kpa (250psi)
liquid line temp: 43 deg c
suction temp: 28.2 deg c

The thing that bothers me is the extra superheat
unit has a small heat exchanger which would explain some extra superheat. If i add more gas to lower the superheat the suction evap temp becomes too high.
Possibly cap tube length is to short?

After coming home checked some tables that I have and I think tube may have been better at 2.01 metres of 0.9 mm bore.

Any help would be appreciated.

[paul_h]

Most commercial fridges have extra long cap tubes to make up for the fact that the evaps are undersized, and most of them have high superheat anyway.
Cabinets with a capillary don't run like a healthy balanced refrigeration system on a TX valve. Most of them do have 20k superheat, from domestics to skope and williams commercial cabinets
Most obvious question is what was the length of the old capillary, was it a different bore or did you not make it the same length for some other reason?

edit: Now that it's down to temp, did you try disconnecting the evap fan and charging until floodback?

[Gary]

On a cap tube system with a heat exchanger, with the cabinet down to temperature, I would expect the suction line temperature near the compressor inlet to be 50-60F/10-15C... and the suction pressure to be whatever it wants to be.

[Temprite]

Thanks for all who replied.

Removed capillary and changed to tx valve with reciever,system working perfect now.

[750 Valve]

Thanks for all who replied.

Removed capillary and changed to tx valve with reciever,system working perfect now.

attaboy, capillaries suck compared to txv's :D

[philfridge]

just like to say this sounds way too short a capalliry line for this application , should be 3 metres then it would have worked a treat i bet. :)

[DAIRYAIR]

Hello, does anyone know cap tube size and length for hussman LBN 5. 1/2 HP, R404a. I have the old tube guess I can measure it but don't know bore size. Just thinking maybe a wire type spark plug gauge if I can find one. Dairyair