Hi Lyn

High-temperature trade waste should be cooled in a cooling tank before discharging into a sewer. The tank must be large enough to hold the hot water discharge until cooled below 50 deg C, before it is displaced by incoming water. If enough cold water is available to add to the the incoming hot water, the tank may be smaller. You can get such a tank at any plumbing or drainage merchant such as Hynds. for more info on trade waste pipe size and materials look at http://www.plumbers.co.nz/forum/index.php/topic,26.0.html

best regards

plumbers.co.nz