Hello All,
I'm hoping I can get some advice from someone out there who may have run into the scenario I'll describe. Thanks ahead of time for taking the time to read this.
I moved into a new house last spring into which we installed a geothermal heating system. The house is 3300 sq ft, lots of windows, open family room, etc. The loop is closed, in three vertical wells and the unit is a ClimateMaster Genesis Split. There is a 3 ton unit servicing the 1st floor (sized to accomodate future basement finishing) and a 2 ton unit for the 2nd floor. The refrigerant line runs to the attic where it connects to a 2 ton Trane Variable Speed Air Handler. The original contractor went out of business before the house was complete without having finished the 2nd floor system (it needed charged and checked out). I got it charged by another company and they retured to adjust it once when it tripped off in the summer.
Now, to the winter and the problems. The loop seems to be working fine
- loop temperatures and pressures are reasonable. The 1st floor unit works like a dream. We have a set temp of 72 deg and even on the recent days when it's been near zero, the unit does not run full-time and maintains temperature. The inlet air temp at a return on the floor is about 70-71 and the exit air temp at the supplies are about 95 degrees. All of this is great, except for the fact that it must be working harder to help the second floor.
My second floor air handler is running 24 hours a day and is still failing to meet the set temperature. I've checked and sealed any ductwork leaks and added additional insulation to the attic. I've got
R30 in the attic and R19 in all the walls. I don't think I'm losing
heat to the attic because on a recent 18 degree morning it was about 19 degrees up there. If I do a heat transfer balance based on the R-values I should have and the 2nd floor temp, that was the correct equilibrium temperature.
I'm also not losing it in the ductwork. The new contractor I have looking at it put his gages on the lineset and said everything looks fine.
If I take the temperature at the inlet and exit of the air handler, I get a delta T of only 10 degrees. I'm pretty sure this is where the problem is, but my HVAC guy has not been able to get out the last couple days to diagnose it further. Any thoughts? (and yes, I've changed the filter.)
Thanks.
Jon