Heat recovery apparatus

Abstract

A heat recovery apparatus comprising a vessel having: a first liquid flow path such that a first liquid can pass through the vessel between a first liquid inlet and a first liquid outlet; a second liquid flow path in thermal contact with the first liquid flow path; and a heater for occasionally heating at least the liquid in the second liquid flow path on an occasional basis. This allows Legionella growth to be inhibited.

1 . A heat recovery apparatus comprising a vessel having:
 a first liquid flow path such that a first liquid can pass through the vessel between a first liquid inlet and a first liquid outlet;   a second liquid flow path in thermal contact with the first liquid flow path; and   a heater within the vessel for occasionally heating at least the liquid in the second liquid flow path.   
     
     
         2 . A heat recovery apparatus as claimed in  claim 1 , in which the first liquid is waste water from sinks, baths or showers. 
     
     
         3 . A heat recovery apparatus as claimed in  claim 1 , in which the second liquid flow path is in series with a cold water main. 
     
     
         4 . A heat recovery apparatus as claimed in  claim 1 , in which the heater comprises an electric heating element. 
     
     
         5 . A heat recovery apparatus as claimed in  claim 1 , in which the heater comprises a third liquid flow path arranged to be switched into communication with a boiler such that warmed liquid from the boiler is passed through the liquid flow path. 
     
     
         6 . A heat recovery apparatus as claimed in  claim 1 , in which the vessel is adapted to retain a predetermined volume of waste water therein. 
     
     
         7 . A heat recovery apparatus as claimed in  claim 1 , in which the vessel has a valve or a flow restriction associated with the first outlet such that in the absence of a flow of liquid into the first inlet the vessel tends to empty. 
     
     
         8 . A heat recovery apparatus as claimed in  claim 1 , further comprising a heat store within the vessel associated with the second liquid flow path. 
     
     
         9 . A heat recovery apparatus as claimed in  claim 8 , in which the heat store comprises a reservoir of liquid through which the second liquid flow path passes. 
     
     
         10 . A heat recovery apparatus as claimed in  claim 9 , in which the heat store is a closed container. 
     
     
         11 . A heat recovery apparatus as claimed in  claim 9 , in which the heat store is an open container. 
     
     
         12 . A heat recovery apparatus as claimed in  claim 11 , in which the heat store is replenished by the waste water. 
     
     
         13 . A heat recovery apparatus as claimed in  claim 8 , in which the heat store is located above the first liquid flow path. 
     
     
         14 . A heat recovery apparatus as claimed in  claim 1  in combination with a boiler, wherein the heat recovery apparatus is an inlet path to the boiler. 
     
     
         15 . A heat recovery apparatus as claimed in  claim 1  in which the heater is operated to heat at least the liquid in the second flow path to at least 50° C.