Lowest temp to operate A/C?

[mxylplik2]

They are finishing my install of a central A/C today (Carrier Infinity - 5 tons; 2-stage condensor; var speed A/H; one zone with return in upper hallway ceiling). Can they test it if the outside temp is 60 degrees or will that damage the condensor?

Also, they moved the return from above the stairs to the ceiling in the hallway - what should be done to seal this return so that cold air doesn't come into the house from the attic? They left the metal box that has a round opening in the back - should I use duct tape to cover? What about using insulation of some sort to tape on the back of the box? Thanks.

[mxylplik2]

One other question,

They installed an Infinity thermostat but they said it can't control the baseboard heat b/c it is not an Infinity furnace/boiler. So I need to have two thermostats on the wall - one for just heat and dthe Infinity one for A/C.

Is he right?

[jacob perkins]

Originally posted by mxylplik2
2-stage condensor;

probably have to test when weather warms up

[dash]

They should seal off the abandoned return duct,a little foam-o-fill would do it.

I don't think the Infinity will control the baseboard heat.

[mxylplik2]

They sealed the back of the return with the insulated foil wrap that you would wrap ducts with. So I think I'm good for now - I can always add batted insulation in the return using the filter to hold it up.

Another question - I went into the attic to inspect yesterday night after the job was done. I noticed that the flex ducts for the lower attic (feeding the middle level in a split-level house) looks different from the other new ducts (black color wrap) that they had installed. It appeared that these silver looking flex ducts are the old ones and that they had not replaced them. The contract indicates that they would replace all ducts with new. Should I make a big deal out of it? Or does this flex stuff last a lot longer than the old "fiberboard" made main trunklines?

[mxylplik2]

Another question - I went up to see the air handler and saw some type of filtration box at the end of the air handler with a plastic marker that showed it was installed in October (can select different months). If I have this (didn't know that it was included in price), do I need an air filter at the return also? Right now, there is no filter at the return.