Patent ID: 7954506

Claim:
A plumbing system for a building, the plumbing system including hot and cold water distribution systems, one or more water-using appliances connected to the hot and cold water distribution systems, a water supply connected to the hot and cold water distribution systems, and a water heater, the improvement comprising: a water supply control valve assembly operable to isolate the water supply from the plumbing system; a liquid injector operable to inject a liquid antifreeze into the plumbing system; a bypass check valve assembly connected to the cold water distribution system, the hot water distribution system, and the water heater, the bypass assembly operable to a first configuration connecting the water supply to an inlet of the water heater, and operable to a second configuration connecting the water supply directly to the hot water distribution system and bypassing the water heater; an antifreeze tank including an antifreeze reservoir and a pump, the antifreeze tank operable to pump antifreeze from the reservoir to the liquid injector; and, a controller in communication with the antifreeze tank, the bypass assembly, the water supply control valve, an ambient temperature sensor, and the liquid injector, the controller operable to operate the bypass assembly between its first and second configurations, to operate the water supply assembly to isolate the water supply from the plumbing system, to activate the antifreeze tank to pump liquid from the reservoir to the liquid injector, and to operate the liquid injector to inject antifreeze into the plumbing system.