Radiant floor heating components: stainless, brass and composite manifolds with 2 to 8 branches, actuators, PEX adapters, tube supports and fasteners, snow-melt controls and installation tools.
The manifold is the heart of the system and the part worth over-specifying. Each loop returns to it, and balancing valves and flow meters on the manifold are what let a long loop and a short loop deliver even floor temperature — without them, the short loop takes most of the flow and the far end of the room stays cold.
Loop length is the other constraint. A single loop much beyond 300 feet of 1/2" tubing develops too much pressure drop to circulate properly, so large areas are split across several loops of similar length rather than one long one. Trunk sizes here are 1-1/4" and 1-1/2".
Radiant systems must use oxygen barrier PEX. Non-barrier tubing lets oxygen diffuse through the wall, which corrodes cast iron and steel components elsewhere in the loop.
Brands include MR PEX, Viega, PexGun and tekmar.
