Circulating hot water system and or appliance

A method of operating a circulating water heating system including multiple water heaters having respective heater inlets connected in parallel to a system water inlet and respective heater outlets connected in parallel to a hot water delivery outlet, the multiple water heaters connected in parallel between the system water inlet and the hot water delivery outlet, a hot water return inlet connecting an end of a building hot water distribution network to the system water inlet,

• a circulating pump adapted to circulate water through the hot water delivery outlet and the building hot water distribution network and the hot water return inlet and the multiple water heaters, and
• a supplemental water flow path connected from the system water inlet to the hot water delivery outlet, the supplemental water flow path including a pressure activated device, the method comprising the steps of:
• sensing a pressure differential across the multiple water heaters;
• opening the pressure activated device when the pressure differential exceeds a predetermined value so that water flows through the supplemental water flow path simultaneously with flow from the system water inlet to the hot water delivery outlet through the multiple water heaters, wherein the supplemental water flow path includes a water storage tank;
• sensing a water flow rate of the system by a flow detector;
• and
• selecting one or more water heaters of the multiple water heaters based on flow rate information from the flow detector.

A water heating system connected to a building hot water distribution network, said water heating system comprising:

• a system water inlet;
• a water delivery outlet connected to the building hot water distribution network;
• a hot water return inlet connected to the building hot water distribution network;
• the water heating system including one or more water heaters, each water heater comprising:
• a heater inlet that is connected to the system water inlet to receive water from a water supply and to the hot water return inlet to receive water from the building hot water distribution network;
• and
• a heater outlet that is connected to the water delivery outlet to deliver water from the water heater to the building hot water distribution network;
• a supplemental water flow path connecting the system water inlet to the water delivery outlet, the supplemental water flow path bridging the water heater or water heaters and including a water storage tank and a flow control device adapted to permit flow from the system water inlet to the delivery outlet through the water storage tank, simultaneously with flow from the system water inlet to the water delivery outlet through the one or more water heaters, when a pressure differential across the water heater or water heaters exceeds a predetermined pressure differential.