Hello there!

My fiancee and I are planning our new (construction) home together and my Dad suggested we look into radiant heating - he has it in Canada and before that, in Austria.  We are looking at a crawl-space construction so something like a "Warmboard" appeals to me.  That said, I have some very basic/general questions:


1. Do you need so many heating "degree days" to make radiant heat a viable option? We live in temperate Charlotte, North Carolina. 

2. More and more construction here seems to be using conditioned crawl spaces and attics.  Does a conditioned crawl space "work" with radiant heating? My understanding is that usually these spaces are conditioned with forced air.

3. How many "zones" make sense for a typical dwelling?  Are zones controlled independently through an in-room thermostat?  Are zones run with separate pipes to the boiler or by controlling valves along a continuous loop?

4. Are home automation systems aware of and able to control radiant heating systems, that might include multiple zones?  I'm thinking of connecting a system like HAI's OmniPro, which uses "Omnistat" thermostats.
   [Edit: Yes, based on http://www.homeauto.com/products/omnistat/rc80.asp ]

5. During the hot months, do I infer correctly that the flooring system is turned off or simply that water continues to flow through the system but that the water is not hot?  (I think I know that one must not attempt to use radiant heat as a cooling method)

6. Is a separate boiler required or can I use the same tankless water heater that I plan for the rest of the house?
   [Edit: General advice seems to be don't use tankless water heater for radiant heating, based on my reading of http://www.greenbuildingtalk.com/Forums/tabid/53/forumid/12/postid/39114/view/topic/Default.aspx ]

7. Is geothermal energy (ever?) a cost effective solution for residential use, (single story home with approximate 2700 sq. ft)

8. Is the water in a closed system, ie: water is never added or removed from the system? What pressure is the water under? 

9. Are chemicals added to the water to enhance the efficiency of energy transfer?


Thanks very much!

PS: It means nothing to anybody else but us, but I've attached a copy of the Frank Betz floorplan we're going with - it's the Durham Hills design.