External Equalizer Line Ices Up

[techservices]

10 Ton Scroll Compressor, R-22 AIR Conditioner
Suction: 51 P.S.I. Discharge: 200 P.S.I.
Condenser water in :75 Degrees
Air Temp entering evap coil :74 Deg
Evap Coil Clean, good air flow across coil
14 Degree :split air across evap coil ( This delta T is normal for these units)
New Power head on expansion valve
I throttled down on the TXV
Superheat measured at suction line feeler bulb : 20 Degrees
I may be overcharged. The suction line and half compressor are really sweating back
There is good amount of foam in the oil sight glass
I gather there is liquid boiling off in the External Equal. Line
Why would the suction pressure be so low?

[valdelocc]

whats the leaving water temp? at 51psi the evap must be iced up, your measurement are kind of screwy

[nyrb]

It seems to me that you have liquid refrigerant flowing through your equalizing line which is giving your TX valve a false evaporator pressure. I'd start with a new TX valve, JMHO.

[coolperfect]

That sounds like an internal leak in the valve,was it doing that before you changed the power head?

[jpsmith1cm]

It seems to me that you have liquid refrigerant flowing through your equalizing line which is giving your TX valve a false evaporator pressure. I'd start with a new TX valve, JMHO.

[VTP99]

What about a restriction in that equalizer line

[bobboan]

The suction line and half compressor are really sweating back
There is good amount of foam in the oil sight glass
I gather there is liquid boiling off in the External Equal. Line
Why would the suction pressure be so low?

Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

Replace or rebuild the valve (if that's possible).

[beenthere]

Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

Replace or rebuild the valve (if that's possible).

Yep.

[coolperfect]

I have seen where the leak at the pushrods is small,just enough to hit the power head and back the valve off.

[Cooked]

Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

Replace or rebuild the valve (if that's possible).

Yep, only gas. I would second that the TXV is suspect.

[bunny]

Liquid is leaking past the O rings on the lift rods. There should be NO liquid in the equalizer line.

Replace or rebuild the valve (if that's possible).

Rebuilding the valve will typically not solve this problem. Most TEVs do not have packings to provide the seal between the pushrods and pushrods hole...there are a few exceptions. The seal is a function of the clearance between the pushrod diameter and the pushrod hole diameter. If the clearance between the two is excessive you will have leakage.

Since all machined parts have a +/- tolerance, there is no telling if the pushrods contained in the parts kit will actually be of a diameter which will prevent the leakage.

Additionally, if a valve is rebuilt, the pushrods will need to be filed down to the proper length (by measuring the pushrod height above the top of the valve, using a pushrod gauge). All pushrods in parts kits are purposefully too long...neglecting to file them down will increase the valve stroke, causing a capacity increase.

Replace the valve.