Effect of OD temp on charge & efficiency...

[alexb]

I can appreciate that the hotter it gets, the more the A/C runs becuase the house is under more heat load. However, I'm interested in understanding the effect of OD temp, on the refer. charge & unit efficiency.

I'm fairly certain, from reading on this site, that the higher the OD temp, the higher the refer pressure (to a certain point.) What effect does refer pressure have on the evap coil temp? (probably a complex question, but I'm interested in the concepts...

With my old 1988 Carrier system (piston metering) the hotter the OD temp, the "less cool" the air from the supply would be. --Seems logical. However, my nice new American Standard system seems to act in the *opposite* direction. It seems that the hotter it gets outside, the colder the supply air temp is. -It's about 93 out right now, the air is colder now, than it was when it was running last nite, when the OD temp was ~75. Why?

If pressure rises when the OD temp rises, and my supply air temp is going DOWN as the OD temp rises (and refer pressure goes up) might it be safe to say that my pressure is not high enough? I know that the contractor didn't consult the SuperCooling chart, when he charged. I think I saw 150psi on the high side, when it was about 87 yesterday, when it was installed.

Help me understand why the OD temp, and the air from my supply travel in opposite directions...

[comfortdoc]

From your other post I see you have a VS blower and setup with Comfort R enabled. It would be normal for the discharge air temp to vary based on the temp/humididty demands from the t'stat.

When charging the unit your contractor very well could have consulted the chart and/or knows it well enough to not need to study it while setting the unit up. He probably weighed in any additional refrigerant needed for the length of the lineset and only needed to verify the charge anyway.

You have a new system using very different technology than than your old system used to provide comfort in your home. If your home is comfortable relax. Give yourself a week or so to get used to the way the new system operates. If yu then feel it is not cooling/dehumidifying the way you expected call your contractor and express your concerns.

You have very nice equipment in your home. Enjoy it.