HVAC with no AC hooked up - help!

We have a new home with Radiant floor heating on all three levels (basement, main and Loft), ICF foundation with HVAC however we currently do NOT have an AC unit, although the rough in is there for the future. I have been unable to find ANYTHING telling me if it's OK (even preferable) to run the HVAC in summer (all year) and if so, is there anything I should watch for?

Can't think of any reason why you couldn't run a/c if you install it. With a really tight house, you may want to install a heat recovery air exchange system to bring in fresh air without losing the money you spent conditioning it.

HVAC means "heating, ventilation, and air conditioning" . What do you want to run? If you have no cooling unit...well you just don't. If you mean can you run the system on "fan" to circulate some air....no problem whatsoever.