I have a Hydron Module ground source system.  I'm not sure on the technical terms so please forgive my ignorance.  Let me explain my system first-  I have a 6-tone heat pump and that keeps water(fluid) heated between 105-115 F in the winter, 35-42 in summer  for a storage tank and that tank is used for my in floor heat and also for a Hydron Module Hydronic fan coil that then serves as the forced air for my upper floor on the heating and cooling side.  I also have a second stage electric emergency / auxillary heat strip in the fan coil.  The question  I have is that it seems to take forever to heat the upper floor to the set temp.  I keep my house set at 73 and the system turns on when it drops 2 degrees.  It also seems to always need the second stage to elevate the temp when the air is on.   In the summer months the fan also seems to run quite often and it doesn't cool as quickly as I thought it would.  My house is also extremely air tight and extremely well insulated (foam).  Today for example when the system finally shut off it took 3 hours for the inside temp to drop 2 degrees (it is about +1 F. outside) and the system to turn on.   My floor heat is great but the forced air is not what I expected.  My heat contractor says that is how this system works and I'm not sure what to believe.  any help would be appreciated.    FYI heat coming out of the registers is around 82 without the auxillary heat and 89 with it.

I'm not an HVAC expert by any means but my understanding is that a "water" coil forced air system is not going to give you the "hot" heat or "cold" cool that you get with a regular heat pump (and far, far lower temp heat than a forced air gas or resistance heat). So you basically have the least comfortable system in the area of your house with the highest load. Too late now but it would have been far more comfortable to have radiant floor heat upstairs too.

Perhaps some HVAC experts can help out here. As I understand it your system does get to temperature throughout the summer and winter but the time to span that 2 degree range is longer than you would like? Maybe with your good insulation it would work to reprogram your system to kick on with only a 1 degree drop. This might help with overall comfort and shouldn't cause short cycle times with your system but I don't have a clue how difficult that would be.

I disagree with gregj-by that I mean that forced air can be very, very comfortable. I do agree, though, that you may be able to help things a little with changing to a 1 deg. drop. Is it set on auto-changeover mode?

It sounds to me that it might be more of a duct sizing/design problem. The temperature of the discharge air sounds a little low. Have you cleaned the air filter? Once a month?

Without seeing it for myself, it's really hard to claim that, but there really might be some sort of duct or blower problem. Are you sure the water coil in the air handler was sized to meet the load of the space? Is the blower set on too high of a speed? Is the duct located outside the conditioned space and is uninsulated? Is the duct completely sealed? What size of air handler unit is it? What is the heating and cooling load of the forced air conditioned space?

Another side of it could be the water piping setup.

Good luck.