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Hi guys, I'm after a bit of advice please.., I have a customer with a 10ft sq 7ft tall coldroom at +3C, the unit cools and defrosts perfectly.
The problem I have is that the main side cover keeps getting forced off by icebuild up on tev and capillary tubes. I went to see the unit today to melt the ice and refit the cover but I was just wondering for possible causes/fixes...?
I'm guessing that this coldroom has forced defrost (electric/hot gas)? You say that the evap. defrosts O.K. (which it would with forced defrost) but for the TEV to ice up in a coldroom that much is abnormal. To me it would indicate that the unit is running longer than normal due to excessive door opening/being left open for excessive periods or the system is running below par i.e. it's achieving setpoint but is running for abnormally long periods to achieve it.
I think the evaporator is right near the door , near a hot kitchen, and with frequent door openings....
The valve is staying open for too long, incorrect valve sizing, mis match of evap for application..........
Sounds to me like gas charge shortage or tev superheat setting incorrect
So which is the correct answer for this problem? :confused: :confused:
If it was me on site I would attach my gauges and see what the system is doing in relation to pressure & temperature, I would already of checked the obvious, evaporator fully flooding, expansion valve closing down and a clear sight glass, if all seemed well I would recalculate the duty of the room and re examine the selection and the match of the evaporator to the condensing unit for the application and check the sizing of the valve. It would probably be totally different if I was on site as I check things automatically, even small things like positioning of the valve bulb in the correct place and not half on a suction and on the edge of a bend or slightly raised from a proper contact due to a swaged joint or fitting, an experienced engineer would know exactly what I mean, something as simple as a poorly sited valve bulb hidden with armaflex tape can create the problems that you have raised. If the super heat has been messed with by another engineer, change the valve, resize the orifice and correctly fix the bulb. Give it a go.Quote:
Originally Posted by Cofreth
Andy W has got it about spot on.
In fact Ive learnt from his very logical approach
Thank You
I am in my 28 th year of refrigeration now, in that time I have experienced a lot of different problems and learnt through my own mistakes and mis diagnosis. Aiyub hit it on the head, logical approach.Quote:
Originally Posted by Aiyub
Thank you very much for the advice/pointers guys, I really do appreciate it.
I shall be going back to see the customer early next week to try and pinpoint this fault. When I was there the other week I did not really have a chance to make a proper diagnosis as the secretary that was there on here own wanted to get home and literally booted me out..
I shall update the thread with my findings when I am allowed a bit more time to play.
Once again, many thanks all and hope the new year treats you all well.
regards...
yes it may be shortages of gas and also in my experiences if the ambient temperature is very low ice will buid up in tev.