superheat

[wicho956]

how can i set my superheat on low temp frozen hussmann cases,r-22 refrigerant

[Magoo]

wicho956.
Expansion valve superheat formula is;
65% fo evaprator TD.
TD is difference between air on and actual evaporating temp.
You will need twin chanel electronic thermometer, and a set of gauges fitted at TX valve thermo bulb, if it does not have schrader fitted , fit one.
Check air on versus evap pressure converted to temp for R22. This is your TD.
Temperature at TX thermo bulb should be 65% of TD.
Any TX adjustments, wait 15 minutes for TX to stabalize. recheck recheck.
Can be done at design or during pull down.
Hope this helps.

[750 Valve]

Can be done at design or during pull down.
Hope this helps.

Watch out doing it during pulldown, it really needs to be closer to design - essentially you need to ensure the valve is not fully open trying to fill the coil still, if you wait 15 mins between adjustments as suggested by magoo this will likely ensure it has sufficiently filled the coil, if not you have other issues.

[Magoo]

Hi 750 valve.
Agreed, the only requirement is that the designer of system selected all the correct valves, OK not likely these days.