Water heating system

A water heating system for a building, comprising: a plurality of water heaters; a water supply circuit for supplying water from the heaters to a plurality of water outlets in the building, the water supply circuit including an upstream portion in which cold water from a cold water supply is received and a downstream portion which is downstream from the heaters; a pump for supplying water through the water heaters and through the circuit; a bidirectional bypass circuit connected to the water supply circuit at a location on the circuit upstream of the water heaters and a location downstream of the water heaters; and a first one way flow/pressure regulating device in the bypass circuit, being configured to allow flow from the cold water inlet to the downstream location and to open only once a predetermined pressure differential has been exceeded so as to create resistance within the bypass circuit to encourage flow through the heaters before flowing through the bypass circuit when water flow requirements through the supply circuit exceed capability of supply through the water heaters, a second one way flow/pressure regulating device in the loop circuit for opening the loop circuit when a predetermined pressure differential exists between the downstream location and the upstream location, for allowing water to flow between the downstream location and the upstream location for supplying a sufficient amount of water to ignite the water heaters. C'J -00 Coj Coj q0 coo coV 0c coCO 0 o co,