Distribution of heat for solar heating systems is complicated by the fact that solar heating systems are more efficient when producing water that is not hot by boiler standards -- that is, boilers can easily produce 160F (or more) water, while solar heating systems are going to be more efficient when producing 120F (or less) water. This makes the heat distribution more challenging, and makes some of the conventional systems difficult to use because of their reliance on high temperature water.
If you have any additional ideas, please let me know.
The new section is here....
A rather neat homemade radiator for heat distribution at the Dawson Creek, YT Visitors Center.
I also updated and added some material to the Heat Exchangers for Solar Heating Systems section... Again, the emphasis is on DIY approaches.