Low energy, low water consumption warewasher and method

The method of washing ware in a warewasher having

• (a) an enclosable wash chamber;
• (b) a wash system including a sump for collecting water at the bottom of the chamber, recirculating pump means having an inlet connected to the bottom of said sump, and at least one wash arm having a plurality of wash nozzle orifices for pressurized spraying of ware in a rack placed in the chamber and being mounted for ratation in reaction to water sprayed from the nozzle orifices;
• (c) a rinse system comprising a supply of fresh water under pressure, a plurality of rinse nozzles in fluid communication with said supply and located above and below said ware, and fill valve means intermediate the fresh water supply and the rinse nozzles;
• and
• (d) a drain system including drain pump means having an inlet and an outlet, a line form the outlet of the drain pump means to a waste line located at a higher elevation than the water level in the sump, the inlet of the drain pump means being in fluid communication with the bottom of the sump, and normally-closed drain valve menas intermediate the sump and the waste line;
• said method comprising the steps of:
• initially filling the sump with water to a normal static fill level substantially above the inlet to the recirculating pump means,
• placing a first rack of soiled ware in the chamber,
• recirculating the wash water for a predetermined period to strip soil from the ware,
• opening the drain valve means and operating the drain pump means to cause water to flow to the waste line until the wash water level descends to the bottom of the sump and air is entrained into the drain pump means to cause drain pump means cavitation,
• continuing recirculation of wash water during draining to maintain water in the wash system,
• discontinuing pumping and closing the drain valve means to drain the wash system to the level of the nozzel orifices,
• then opening the fill valve means for a minimum volume of fresh water adequate to thoroughly rinse the ware and upon completion of the rinse period draining the rinse system in to the sump to the level of the lower rinse nozzles,
• the water received from draining of the wash system and from rinsing combining in the sump to return the water level approximately to the normal static fill level and thereby to provide for a next following rack of ware a wash water volume which is substantially in excess of the water supplied by the rinse system alone,
• removing the rack of washed and rinsed ware from the chamber and replacing it with a second rack of soiled ware, and
• activating the recirculating pump means to recirculate the combined retained water to wash the ware in the second rack.