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 catalytic tank heater includes a removably attached catalytic heater cartridge having catalytic material. The heater is attached to an LPG tank to position the catalytic heater cartridge to face the tank. The catalytic heater cartridge covers a plenum chamber of the catalytic tank heater. A fuel distribution header and heating element are positioned within the plenum chamber and are controlled to initiate combustion of the catalytic material to heat the tank. Vapor from the tank is provided as fuel to the catalytic tank heater, and is regulated to increase heat output as tank pressure drops. The catalytic heater cartridge can be replaced with a new cartridge while at the location of the tank on a property.

A system for reducing buildup of solids in pipes used in underwater oil operations is disclosed. The system includes an annular pipe having an inner pipe wall and an outer pipe wall. The inner pipe wall defines an inner pipe configured to transport an oil. The outer pipe wall is displaced from the inner pipe wall. The outer pipe wall defines an outer pipe between the outer pipe wall and the inner pipe wall. The system includes an oxidizer delivery pipe having an oxidizer delivery outlet. The oxidizer delivery pipe is configured to supply an oxidizer to the outer pipe. The system further includes a fuel delivery pipe having a fuel delivery outlet. The fuel delivery pipe is configured to supply a fuel to the outer pipe. The oxidizer and the fuel release thermal energy in an exothermic reaction.

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.