If you want a complete heating system, use a complete system designed by a radiant heating manufacturer. Weil McLain and other manufacturers will provide an entire factory-warranteed package installed by a qualified representative.
http://www.radiantdesigninstitute.com/page2.html
http://www.radiantpanelassociation.org/
http://www.hydrothermcan.com/products/design.html
http://www.runtal.com/
http://www.radheat.net/
http://www.radiantheat.net/leaks.htm