hack expanion valve install...

[mark 11]

got a call today from new customer with walk in cooler
out,found large leak at expanion valve flare nut,it
was a R 12 external equalized expanion valve with
external port capped off, external 1\4 line brazed
closed, the owner said it was working fine like that
for years,i figured previous tech was just to lazy to
connect external line,but wondering how that valve would
feed like that?gave owner price to convert system to
R-22 as condenser was severely corroded as well,any
thoughts on how that valve would work like that????

[Wild Leg]

It just happened to be in a position that would let some refrigerant through.

It would have acted like a fixed-bore metering device (cap tube).

[mrfreeze666]

THE 1/4 EQUALIZER IS TO BALANCE THE PRESSURES IN THE OFF CYCLE. CHECK TO SEE IF THERES A 1/4 TUBE ON SUCTION LINE IF SO, THEY DIDNT WANT TO HOK IT UP FOR SOME REASON. IF THERE IS NO EQUALIZER TUBE I WOULD SAY THEY PUT IN WHAT THEY HAD.

[Wild Leg]

Originally posted by mrfreeze666
THE 1/4 EQUALIZER IS TO BALANCE THE PRESSURES IN THE OFF CYCLE. CHECK TO SEE IF THERES A 1/4 TUBE ON SUCTION LINE IF SO, THEY DIDNT WANT TO HOK IT UP FOR SOME REASON. IF THERE IS NO EQUALIZER TUBE I WOULD SAY THEY PUT IN WHAT THEY HAD.

I don't think so. :(

A TXV with an external equalizer is used on coils with large pressure drop, or coils using a distributor.

It is used so that the pressure & temperature used to determine superheat will be measured at the same place on the coil.

The equalizer port must NEVER be plugged, as the valve becomes locked in position.
A tube should have been put in place, or a valve with internal equalizer used.

[eng2sales4mny]

Correct. It is not to balance pressures between high and low sides, an orfice will eventually do that. It is to compensate for pressure drop through the evap. With out it the valve could be fooled looking at only temperature and think that the superheat was lower than it actually is. This would cause underfeeding and higher than normal superheat. Check out Sporlan's website and TXV literature, they have a great explanation of this there.

[rayr]

Education is a beautiful thannnnnggggg!!!!

[Wild Leg]

Originally posted by rayr
Education is a beautiful thannnnnggggg!!!!

Ayup!