Receivers

[get the gauges]

I have recently come across a system that has a HELPMAN receiver that is quite visibly full of liquid from looking at the upper receiver sightglass when running. Were talking about 30 kgs + of gas and i wonder how this can be right.What is the purpose of this amount of standing liquid ,there is a system next to this one which has the same full receiver. I reckon i could take 10-15 kgs from each tank with no problem as long as the diptube is well below the line of liquid. Someone has left the system like this am i missing something. Thanks

[US Iceman]

Has the unit had head pressure control valves added to it? If it has, the liquid used to block off the condenser surface may just be settling in the receiver after the condensing pressure starts to rise above the control valve setting.

Or, it may be just as simple as....someone over-charging the units.

[get the gauges]

Has the unit had head pressure control valves added to it? If it has, the liquid used to block off the condenser surface may just be settling in the receiver after the condensing pressure starts to rise above the control valve setting.

Or, it may be just as simple as....someone over-charging the units.

No head pressure valves fitted. Could you explain exactly how that set up works for the benefit of anyone reading this or people seaching for 'Head pressure valves' . I have some understanding of how it works but the bit about blocking off the condenser eludes me a little. Thanks Steve. P.s It's probably overcharged

[US Iceman]

It's simple. The head pressure control valve settings allow liquid refrigerant to back-up into the condenser thereby reducing the heat transfer surface area. It's the same concept as putting a piece of cardboard over a car radiator in the winter.

In the summer when the discharge pressure starts to increase due to the higher ambient temperatures; the liquid has to go some place. That place is the receiver.

If you don't have head pressure valves, then it's probably over-charged however, you might want to investigate how it came to have that much refrigerant put into the system. Perhaps they were having problems with low discharge pressures in the winter and someone thought that might cure the problem.

[get the gauges]

It's simple. The head pressure control valve settings allow liquid refrigerant to back-up into the condenser thereby reducing the heat transfer surface area. It's the same concept as putting a piece of cardboard over a car radiator in the winter.

In the summer when the discharge pressure starts to increase due to the higher ambient temperatures; the liquid has to go some place. That place is the receiver.

If you don't have head pressure valves, then it's probably over-charged however, you might want to investigate how it came to have that much refrigerant put into the system. Perhaps they were having problems with low discharge pressures in the winter and someone thought that might cure the problem.

So if i had a high pressure valve,in the winter i'd have a back up of liquid in the condenser to build up pressure, but in the summer when the condensing pressure builds quickly the satisfied HP valve will open and build pressure up to the TEV. The high liquid level would be the extra gas needed to build pressure in the condenser in low ambient conditions i take it, and the receiver is the place it is stored until next winter. ok.
In my case i have a shell and tube seawater condenser with hp seawater valve, my conditions are in a low ambient condition for the fresh air only on to coiling coil, may be when there is a bit if load come the great British summer the liquid might find it's way into the evap. Thanks

[shooter]

yes it is overfilled, check the expansion valves for correct setting, if possible exchange them for electronic ones as standard you will need about 10 bar difference to operate.
When filling the condeser the pressure will build up and the evaporator will do its job, however the compressor will have to work too hard. better use a control valve as expansion valve.
check also the filling of the coolers and the temperature they are running on.
example:
seawater is 10 degrees.cold air is also 10 degress brrrr pressure on both sides is same so no expansion.

also possible is to use a liquid pump to get the pressure needed that way you wont have to change all evaporators.
this is most energy efficient way and cheap as you only need 1 small pump.