AXV

[hvac3901]

dying to know this one for sure.

if the pressure in the evaporator were to increase with the load the responce of the AXv would be what?

[speedracer]

With increasing evap pressure, the txv will close down a bit. It's a trick question though, because at steady state, the first thing that will happen is that superheat goes up, causing the valve to open a bit. This is necessary before pressure can increase.
BTW, I've never heard of the term AXV, so I'm assuming it's the same as TXV? Pardon my ignorance if not.

[collegetech]

THE AUTOMATIC EXPANSION VALVE RESPONDS DIFFERENTLY THAN THE TXV TO LOAD CHANGES. IT ACTUALLY ACTS IN REVERSE. WHEN A LOAD IS ADDED TO THE COIL, THE SUCTION PRESSURE STARTS TO RISE. THE AXV WILL START TO THROTTLE THE REFRIGERANT BY CLOSING ENOUGH TO MAINTAIN THE SUCTION PRESSURE AT THE SET POINT. THIS HAS THE EFFECT OF STARVING THE COIL SLIGHTLY. A LARGE INCREASE IN LOAD WILL CAUSE MORE STARVING.

[Wild Leg]

Originally posted by speedracer

BTW, I've never heard of the term AXV, so I'm assuming it's the same as TXV? Pardon my ignorance if not.

AXV is different from TXV.

AXV (Automatic Expansion Valve) is essentially a pressure regulator.

It does not actively control superheat, as a TXV does.

It is useful to prevent overpressurization of the evaporator & resulting compressor overload, during high load conditions.

Capacity of the system is lower during high load, but it will stay running and eventually catch up.

[hvac3901]

Is'nt that just a bit%*. I thought twice about that question and had a really bad feeling anyway. I should have known better. Does that mean I know something about this stuff now, seeing as how i forgot something? Or that i should hurry up and join RSES before its too late for me.

CollegeTech,
you did'nt have to make another thread about the same thing. and CAP LOCK means your shouting or mad, when you type. Thanks for the detailed reply.

[thegoodhumorman]

"back in the day" installed axv's on
Scotsman MF flakers- those big 2000 lbers,
even a few of the SF 5s side by side jobs.
Haven't seen very many otherwise- these were used as replacements of cap tubes. Even loads.

Put some on a couple Cornelius flakers-
unrelated but boy those things worked extra good when
the barrel leaked oil into the water.......

[rimek]

We use 'em as unloaders sometimes to prevent interstage heat exchangers from getting too cold.