Checking numbers

[daviddsims]

I was a little worried with the amp draw at 12.5 and still getting into the hottest part of the day. The FLA was 14.4

[garyed]

SP=82
DP=255
SL temp=65
LL temp=110

Still not completely happy with the results.

Those numbers look pretty good if it was 103 outside.
If your TD across the evaporator was 15 or so you may be O.K. depending on the inside coinditions. What about your indoor DB & WB?

[hvacrmedic]

I was a little worried with the amp draw at 12.5 and still getting into the hottest part of the day. The FLA was 14.4

The amp draw could be normal. The compressor in the pdf file below has an RLA of 14.4. It may not be the compressor in your unit, but yours should have a similar amp draw profile. The RLA is for sizing the circuit/protectors feeding the unit, and isn't equivalent in function to the FLA of a fan motor. Compressors are actively cooled by returning refrigerant and can run all day long at higher than RLA. A fan motor OTOH, will generally trip out on thermal overload if it runs very long at higher than FLA.

BTW, looks like the high suction pressure isn't really high in this case. There's a huge difference between a cap tube system and a high efficiency TXV system.

[hewitt]

With103 outside system seems to be okay.Remember design conditions are 95 od 75 id with 50% humidity

[hvacrmedic]

With103 outside system seems to be okay.Remember design conditions are 95 od 75 id with 50% humidity

There are so many standards for different purposes it's difficult to keep them straight. The rated capacity of a condensing unit is from these conditions.

Cooling Standard: 80°F (27°C) db 67°F (19°C) wb indoor entering air temperature and 95°F (35°C) db air entering outdoor unit.

I cut and pasted that to make sure I got it right.

Design conditions (Manual J) depend upon the location and local codes. Maybe that's what you were referring to? Yep, they don't tend to keep up when design conditions are exceeded, unless they're over-sized like mine. It stays 75° in my house even when it's 110° out. In my book it's sized just about right, and it wasn't by accident either.

[MechAcc]

Lennox uses the approach method in conjunction with subcooling for charging. Their approach temperatures are below 10 degrees. Check the installation instructions for Lennox AC units.