High super heat.

[Furlo]

Hey guys,


I've was checking out my friends system. I have a 9 on my sub cooling target is 10 but my target superheat is 15 my actual is 23, it is a txv system.
The return supply split, is 77 going in and 66 going out, also it's a r22 system.
Any thoughts about the low split. Duct work looked ok. I am thinking low on freon.

[socotech]

Pressures? Compressor amps vs FLA? Package unit or is the AHU in an attic? Ambient temp? Where are you measuring return temperature? Need more info

[Saturatedpsi]

Normally, 9˚ subcooling is enough to load the evaporator, but have seen a few instances where a few more degrees of subcooling eventually loaded up the coil and brought down the superheat. It's either undercharged, the TXV is underfeeding or there's a liquid line restriction before the TXV.

[sarge]

Slow the fan down.

[sarge]

I mean, check static presure and verify airflow.

[sarge]

350-450 cfm per ton, then adjust freezone.

[Furlo]

Suction line pressure is 67, liquid line pressure is 209psi ambient temp at cu is 89. Indoor wet bulb temp is 67 at return grill suction line temp is 62 liquid line temp is 9. Ahu is in actic.

[gravity]

you still dont have all of the info to properly diagnose from across the USA. My guess would be to jump the subcooling up a little more. how long are the lines? you could read 9* at OD unit but really have 4-5* at the a/h due to long lines and attic heat. have you verified that your tools are accurate?

[Furlo]

Lineset is only about 40 feet. When I get back over there I am probably going to make sure the door to the Ahu is sealed up and then add some freon and see if my supperheat drops. So my question is actic air could raise my supper heat but not my subcooling?

[Furlo]

Sorry liquid line temp is 95.

[hvacvegas]

fan is moving to much air.
Or a mix of underfeeding txv + extremly high humidity.

[BaldLoonie]

Temp readings are right at the AH, not at registers?

Leaks in return can add to SH since that is load on evap. 67 wb says it is a bit humid but that alone won't cause 10° drop.

[rickboggs]

Why would I check temperature difference? I do it all the time, but only for self satisfaction. If the unit is designed for a SHR above .85 my target TD would be 21 degrees, if my SHR is below .80 my target TD 17 degrees.