Not to be picky, but Radiant floors can't cool. Cold floors do not have the same effect as warm floors, something to do with heat rising.

 

We have installed a number of radiant floors along with forced air cooling systems in homes with EarthLinked DX units. This is an expensive approach, but it can be done.

Just as example... If a 5 ton forced air system (turnkey) were to sell for $28,000.00, then to add radiant to that would add anywhere from $12,000-$22,000 to the price. Of course, these are just guesstimate ballpark numbers. The efficiency of closed loop water heating for radiant is usually lower than just forced air, too. Instead of measuring in the field averages of 4.5 COP (450% efficiency), the radiant systems usually yield about 3.3-4.0 COP. This still beats the heck out of fossil fool systems.

Radiant cooling can be done, but don't do it from the floor. www.bekausa.com has the stuff that is proven to work. It's just not easy to get installed in the U.S.

Folks that want in floor radiant are going to spend much more initially, but enjoy very constant and even winter temperatures. Depending on how mild your climate, adding the additional vehicle to your HVAC plan may be somewhat extravagent. You can off set some of the additional expense by installaing your own loops, but if you do, coordinate with your geo installer to avoid oversizing and creating additional load.
As all have pointed out, these tubes will not cool your home. Therefore you have to install duct work anyway. With a water to water geo system, or DX, you could use a high pressure or conventional duct system with fan coils, but again design is critical. Use of a variable speed fan with a water to air system, for heating and cooling, goes a long way toward the even temperatures desired by radiant floor buyers.
Because conditions are geographically unique, yours is a case where a local guy is going to be the best one to help you design your system. Unless someone has a ton of extra money they don't know how to spend, I really don't see infloor radiant being a big seller in a cooling dominated climate.
Spending the money on any geo system will pay you back over and over.
Good Luck,
Joe

Here's a good example of someone in Maryland with in-floor radiant heat and forced-air cooling, all geothermal GSHP based: http://www.ourcoolhouse.com/ .

Best regards,

Bill

Thanks Bill Great site ! Some say you cannot 'cool' radiant flooring but these seems to prove it works! Wonder if they have a traditional A/C and duct heat system in addtiion

John

Joe RE"Spending the money on any geo system will pay you back over and over." Good point however getting a 'local guy' in Ca. has been difficult... Thanks, John

 

I don't think so.  I think Phil has forced air cooling only - no furnace, and that all heating is done via in-floor radiant.

Feel free to contact him via his forum.  He's typically very responsive.

Instrumentation on his Maryland home is at http://welserver.com/WEL1000/ .  He has a WaterFurnace water-to-air GSHP for forced-air cooling, and a WaterFurnace water-to-water GSHP for radiant in-floor heating and domestic hot water generation, using one common vertical water loop, with antifreeze.

Best regards,

Bill

John,
If you can't find a local dealer, try manufacturer web sites. They know who they sell to.