TXV overfeeding

[Mpz6942]

I replaced a 26ton sporland TXV with a new emerson 26 ton valve ...Original symptoms low superheat, low suction, coil has been chemically cleaned Air flow good 12deg sub cool clear sight glass.......same symptom after un able to adjust.

[pvc1984]

It could be loose bulb connection or poor bulb placement. Make sure the bulb is well insulated.

Is the txv adjustable?

[Chuck]

Well, low SH and low suction pressure does not indicate a txv problem.

It means you have low load. Verify correct evaporator airflow.

What make and model unit?

[USC21]

Location of Sensing bulb? Insulation around bulb?

[Six]

That doesnt sound like a bad TXV.

Whats the delta across the coil ? TXV failure is actually pretty rare. Power head maybe but not the valve.

Sounds like low air flow. Coil cozld be clean but it might have an adjustable shiv on it.

[beenthere]

Air flow good? How many CFM is that?

What was your delta across the indoor coil? 16°, 20°, 26°?

What was the outdoor temp?

[bunny]

While it's a pain to check, this sounds like a classic case of an oversized distributor nozzle. If there's too little pressure drop through the nozzle the liquid and vapor will not properly mix, causing the lower circuits to receive too much liquid (resulting in the low superheat) and the higher circuits receive too little liquid (resulting in low load).

[Juan Madera]

Or could be the orifice in the distributor is MIA........

[Six]

While it's a pain to check, this sounds like a classic case of an oversized distributor nozzle. If there's too little pressure drop through the nozzle the liquid and vapor will not properly mix, causing the lower circuits to receive too much liquid (resulting in the low superheat) and the higher circuits receive too little liquid (resulting in low load).

he just replaced the valve.

you think it never had the correct orrifice in it ?

[Juan Madera]

....or someone thought it would "improve" the performance if the restriction to flow was gone?

Do you always check for the presence of the restrictor in the distributor? Or do you (as I have) take it for granted that it was there and correct for the equipment... Just as I don't expect that the previous tech was twiddling with the superheat adjustment to correct an airflow issue. Anymore, I have learned that if it has been "serviced" the all bets are off the table on what you might find.