Wirsbo Radiant Floor Heating Systems, Wirsbo Snow & Ice Melting Systems, Wirsbo Permafrost Protection Systems, the valved manifold for multiple zoning applications or when flow balancing between loops on the manifold are required. Two valveless manifolds are used when the manifold location is serving only one zone and all loop lengths across the manifold are equal. This valveless manifold is normally installed as the supply manifold.The 2, 3 and 4 loop manifolds can be joined to create any manifold combination up to ten loops for radiant floor and eight loops for snow melting.