expat
08-12-2007, 11:40 AM
I got called to a butchers with a problem with his display cabinet. He said it was short of gas as he saw bubbles in the sight glass.
Upon inspection I found high SP, low HP, loads of SH and so concluded that he was right.
Now I could not for the life of me find any leaks, neither with aerosol leak detecter or a sniffer. There were no hidden joints so I was perplexed.
I charged up with 1kg of R22 and got my SP to about 2 bar (29 psi).
This gave me 7K SH, as I measured 7°C (45°F) at the evap exit.
The HP was 11.5 bar (165 psi)
32.5°C (90.5°F) at condenser exit
Condenser air on 19°C (66°F) air off 31°C (88°F)
Now I didn't want to add more gas willy nilly to raise my head pressure for fear of also raising my suction pressure.
Now the evaporator is divided into five sections; two going left fed by one TXV and three going right fed by another TXV. The left evaporator is about 1m10 long and right is 4m60.
Before I left he asked me to quote on dividing the right hand evaporator in two and adding a third TXV to better distribute the *****. I said I would think about it!
Sorry this is so long, nearly finished!
He also told me he often needs a gas recharge when going into summer and again going into winter.
1 How come a butcher thinks he needs another TXV?
2 How come someone has changed the origional TXVs for external pressure equalizing?
3 How come he needs gas recharges in winter and summer but I can't find a leak?
One more thing, the condensing groupe is a maneurope with twin ventilators. After blocking half the condenser I got the head pressure up to 16bar (230psi), the SH remained stable and the sight glass improved but still had bubbles.
I'm thinking of putting a pressostat to cut one or both ventilators when ambient is low, to keep the HP up and charging with a little more gas.
Any comments welcome.
ps I don't think there is a leak, I think he gets a recharge in winter and then a discharge in summer!
Upon inspection I found high SP, low HP, loads of SH and so concluded that he was right.
Now I could not for the life of me find any leaks, neither with aerosol leak detecter or a sniffer. There were no hidden joints so I was perplexed.
I charged up with 1kg of R22 and got my SP to about 2 bar (29 psi).
This gave me 7K SH, as I measured 7°C (45°F) at the evap exit.
The HP was 11.5 bar (165 psi)
32.5°C (90.5°F) at condenser exit
Condenser air on 19°C (66°F) air off 31°C (88°F)
Now I didn't want to add more gas willy nilly to raise my head pressure for fear of also raising my suction pressure.
Now the evaporator is divided into five sections; two going left fed by one TXV and three going right fed by another TXV. The left evaporator is about 1m10 long and right is 4m60.
Before I left he asked me to quote on dividing the right hand evaporator in two and adding a third TXV to better distribute the *****. I said I would think about it!
Sorry this is so long, nearly finished!
He also told me he often needs a gas recharge when going into summer and again going into winter.
1 How come a butcher thinks he needs another TXV?
2 How come someone has changed the origional TXVs for external pressure equalizing?
3 How come he needs gas recharges in winter and summer but I can't find a leak?
One more thing, the condensing groupe is a maneurope with twin ventilators. After blocking half the condenser I got the head pressure up to 16bar (230psi), the SH remained stable and the sight glass improved but still had bubbles.
I'm thinking of putting a pressostat to cut one or both ventilators when ambient is low, to keep the HP up and charging with a little more gas.
Any comments welcome.
ps I don't think there is a leak, I think he gets a recharge in winter and then a discharge in summer!