My parents and in-laws both have geothermal. The one thing that we notice is that when the furnace is running, at say 75 degrees, the air coming out of the vents is 75 degrees, and blowing hard. It's not like combustion forced air that you would go and stand near a register to warm up. Being near a register when it's blowing can be quite drafty. Same with the AC, It's COLD. But both sets of parents love the low utility bills and wouldn't trade that for the world.