I'm standing in a cramped attic in a one-year-old house, trying to discover the problem
with the ground-source heat pump in front of me. As an engineer who tests dozens of
heat pumps each year, I often get called in to troubleshoot problems no one else is able
Within a few minutes, I determine that one of the two compressors in this two-speed
heat pump has shut down. I also discover that the return duct is undersized, causing
extremely low air flow, and the supply duct to one particularly cold room is losing more
than half its air through leaks into the attic.
These discoveries explain