-Housing is an epoxy coated stainless steel tube. Elements are Incoloy 825. -Power consumption 3kW. -Max current drawn = 13 Amp (thus can be plugged into ring main via normal plug). -Max system pressure = 3 bar. Minimum water flow = 1000 litres / hour (220 gallons). -Temperature control range 0 to 40 deg C (depending upon ambient). Over temperature thermostat cuts out at 44 deg C. -Flow switch fitted with time delay. Switch must be closed for a continuous period of two minutes before heating begins. This ensures that there are no pockets of air are left in any part of the system. -Filter pump interlock works on volt free contact which is different to a conventional Thermalec. If terminals 14 and 15 are shorted together then heater can operate. -For usual domestic use, a wire link is fitted and the flow switch is relied upon to guard against "dry" heating. For a permanently wired installation the link should be removed and terminals wired across an auxiliary contact on the filter pump contactor. -Not suitable for salt water use