I had an additional room finished recently, and the contractor added a supply and return from the existing system. The air handler is in the attic.
To make a long story short, I'm experiencing obvious efficiency losses from having the ductwork and air handler in unconditioned space, and I'm just wondering if they are typical, or shoud I look for leaks in the return side of the system (possibly introduced with the new work, but not sure).
Anyway, it's 96F out today, and my roof is currently taking full sun, so it's probably well in excess of 100F in the attic.
I have a remote temperature sensor sitting in the blower compartment just inside the filter, so I'm getting a pretty good read of the return air as it enters the blower.
The temperature upstairs in the house at the thermostat is 76F, but the air in the return only gets as cool as 80-81F right now. So, it's gaining 4-5F versus the indoor temperature. (At night, on the other hand, they will be about the same). Of course, all the returns are in the ceiling, so I may be drawing in slightly warmer air than is present at the T-stat.
Do these heat gains seem unusual? The ductwork is only R6 flex. The return plenum is wrapped also, probably just R4.
(System is maintaining the set point and occasionally cycling off, so this is mainly an efficiency question)