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Peter_1
28-06-2007, 07:45 PM
Is the TEV wide open after an electrical defrost in case of a pump down and in the case of not pumping down where pressure can build up while defrosting?

taz24
28-06-2007, 08:14 PM
Is the TEV wide open after an electrical defrost in case of a pump down and in the case of not pumping down where pressure can build up while defrosting?


Hi ya Peter.
I would of thought that the valve would be wide open initialy straight after the defrost because of the increased superheat in the suction line.
As regards the pump down or not, I would think that again the valve would be open due to the increased temp caused by the electric defrost.

Cheers taz.

monkey spanners
28-06-2007, 11:23 PM
Hi Peter

I think the one on pumpdown would be more open than the one not on pumpdown, assuming the valves and evaporators reach the same temperature on defrost.

Silly thought time, should we not call it defrost and refrost:rolleyes:

Jon

mohamed khamis
29-06-2007, 09:50 AM
Is the TEV wide open after an electrical defrost in case of a pump down and in the case of not pumping down where pressure can build up while defrosting?

Hi Peter_1

Of course, the TXV is wide open in the pumping down system comparing to that in not pumping down. The reason is in pumping system the mount of still refrigerant in the low-side is small as a result of the most of the refrigerant is entrapped behind the solenoid valve and settled in the receiver. Accordingly, when the electrical defrost is activated the degree of superheat is increased significantly with a small evaporating pressure (small refrigerant amount), the net resultant force applied on the TXV diaphragm is accounted for a favor of more opening area of the TXV port. And of course the two TXV are balanced port to cancel the effect of the pressure drop on the the TXV port.

Cheers:)