Low head loss systems are detailed. The systems may include chambers having low impedance to water flow therethrough and repositionable gates or other valves within the chambers. The valves may direct water as a function of whether an associated heating device is active. At least some gates may incorporate poppet valves or other high-flow by-passes.

Low head loss systems are detailed. The systems may include chambers having low impedance to water flow therethrough and repositionable gates or other valves within the chambers. The valves may direct water as a function of whether an associated heating device is active. At least some gates may incorporate poppet valves or other high-flow by-passes.

A filter assembly for an additive manufacturing apparatus has a housing defining a gas inlet and a gas outlet. A filter element is located within the housing between the gas inlet and the gas outlet. The assembly includes valves that can be actuated to seal the gas inlet and the gas outlet. Additionally the assembly has a fluid inlet for allowing ingress of a fluid into the housing. The assembly allows a filter element, which may contain volatile particles, to be changed safely. By sealing the gas inlet and outlet and flooding the housing with a suitable fluid, volatile particles captured by the filter can be neutralised.

A boiler loop system including a primary-secondary piping loop interface apparatus including a flow diversion device, and a drain valve, and a drain port in branches from a circumferential sidewall. In an embodiment, supply branch piping and return branch piping connect the primary-secondary piping loop interface apparatus to a boiler and provide attachment points for auxiliary plumbing equipment. In an embodiment, the boiler loop is integrated into the primary loop.

A water heating system having a system inlet pipe (1.002), a hot water delivery pipe (1.003) and a hot water return pipe (1.006) connected to a building hot water distribution network (1.024); the water heating system including one or more water heaters (1.001), the or each water heater having a heater inlet (1.022) and a heater outlet (1.023), a hot water return pipe (1.006) connected between the system inlet and delivery outlet via the building hot water distribution network to form a close loop hot water supply-return circuit; a pump (1.005) connected to circulate water through the hot water supply-return circuit whereby the pump can circulate water through one or more of the water heaters; a valve means (1.007) a first non-return valve adapted to prevent inlet water (water delivered to the system inlet) from flowing into the hot water return pipe or the building hot water distribution network.

A boiler loop system including a primary-secondary piping loop interface apparatus including a flow diversion device, and a drain valve, and a drain port in branches from a circumferential sidewall. In an embodiment, supply branch piping and return branch piping connect the primary-secondary piping loop interface apparatus to a boiler and provide attachment points for auxiliary plumbing equipment. In an embodiment, the boiler loop is integrated into the primary loop.

A boiler loop system including a primary-secondary piping loop interface apparatus including a flow diversion device, and a drain valve, and a drain port in branches from a circumferential sidewall. In an embodiment, supply branch piping and return branch piping connect the primary-secondary piping loop interface apparatus to a boiler and provide attachment points for auxiliary plumbing equipment. In an embodiment, the boiler loop is integrated into the primary loop.

A water heating system having a system inlet pipe (1.002), a hot water delivery pipe (1.003) and a hot water return pipe (1.006) connected to a building hot water distribution network (1.024); the water heating system including one or more water heaters (1.001), the or each water heater having a heater inlet (1.022) and a heater outlet (1.023), a hot water return pipe (1.006) connected between the system inlet and delivery outlet via the building hot water distribution network to form a close loop hot water supply-return circuit; a pump (1.005) connected to circulate water through the hot water supply-return circuit whereby the pump can circulate water through one or more of the water heaters; a valve means (1.007) [a first non-return valve] adapted to prevent inlet water (water delivered to the system inlet) from flowing into the hot water return pipe or the building hot water distribution network.