Evaporator-coil/condensor compatibility

[Bain]

While checking out new construction yesterday, I noticed that the size of the interior coil was two and a half tons, while the exterior condenser was a three ton unit. I see this all the time, and wonder if there's a reason for it. I was taught that both coils should be the same size, but I see mismatches all the time. Are these mismatches incorrectly installed?

John

[Scottpat]

Its wrong. If anything the evaporator coil should be 3 tons and the condenser 2.5 tons. In the South we like to see evaporator coils over sized by .5 tons.

The condenser should never be larger than the evaporator coil.

[Bain]

Thanks, Scott. Is that the industry standard, or is it in writing somewhere so it can be referenced?

John

[Scottpat]

Industry standard is a matched system. That means that they should be the same size. I would contact the manufacture of the equipment. Many times it is also listed on the equipment itself.

[rlskfoster]

I know how to find the outside condensor coil size but I don't know about the interior evaporator coil?

Well let me backtrack a second. I always read the model # and if there was a 36 it was 3 tons, 42 is 31/2 to, etc. Is this wrong?

is the interior coil marked the same way or is there another method that I don't know about.

To be honest I haven't been checking for comparable sizes because I didn't realize I should. Uh Oh! Learn sometning knew every day. Thats why I love this site.

Buster

PS I tried to tell a fellow inspector about this site and he said, " well, not to brag, but, in 14 years I think I've seen about all there is to see."

Oh well its his loss.

[Bain]

Buster,

The size of the evaporator coil is nearly always included within the model number. It's expressed as BTUs so look for 24, 30, 36, etc. Lennox is one company that makes determining size difficult. On their condensors, for instance, they add one to the size, so ton-and-a-half units are labeled "19," and two-ton units are marked "25."

As for sizing all units, there's a manual for sale that lists the model numbers of nearly all pieces of equipment and their corresponding capacities.

John