thermostatic Expansion valve location

[dolce]

I have cold store -40 C and 2 evaporators feed by thermostatic Expansion valve each one my question
which you prefer put Expansion valve near evaporator in cold store -40 C or far from evaporator about 2 meters out the cold store +30 C


Thank for help

[Aik]

TEV must situated near the evaporator...Why do you want to install it far from evaporator?
Check:
http://www.refrigeration-engineer.co...ad.php?t=23692

[mbc]

In -40 your suction pressure is low and to get good result of TEV to sense of suction temperature it better you put near Evaporator

[dolce]

[quote=Aik;190754]TEV must situated near the evaporator...Why do you want to install it far from evaporator?

thank you for help
I do not want to install it far from Evaporator it already install far from evaporator now iwant to re-install it correctly near evaporator is that the best?

[Aik]

Without any doubts...

[al]

It depends, on evaporators that need a hoist to access it can be better to mount the TEV externally to the room to allow for service access, the last room i fitted i placed the valve on the roof with no issues, realistically you're only extending the pipe inlet by less than a meter.

alec

[cool runings]

.

Outside the room, on the roof will ease the repairs and maint of the TEV in the system.

If the pipes are correctly lagged then the differance between inside and outside will be minimal.

If the sytem is working ok as it is then leave it.

Coolroonings.

.

[coolhibby1875]

have seen many a valve mounted on outside of room, as long as the pipes are well insulated as well as the valve i dont see any problem.

[lana]

Hi there,

If your TEv is MOP type then the valve head must be warmer than the bulb. To put the valve outside creates this temperature difference.
What I do is : I use drain heaters (like cable) on top of the valve head.

Cheers

[wendecai]

Can anyone tell me ,what is the difference between Txv with Mop and Txv with Mop?

[Scramjetman]

That's an easy one. They are both the same.

The penalty with moving the valve upstream of the evaporator is the extra pressure drop in the line between the valve and the evaporator. That line effectively becomes an extension of the evaporator. Provided this extra pressure drop is accounted for and the line external to the room is insulated (you don't want to be wasting power trying to cool the world) it should work ok.

[Paul J]

MOP = maximum operating pressure, basically the valve will operate like a crankcase pressure regulator and will not allow the suction pressure to raise above its "MOP", this can cause some problems during start up and pull down like in a blast freezer after a defrost, the suction pressure will remain constant untill the air temp/suction pressure drops, it helps the compressor get hold of the load without tripping on amps etc