Stuart Turner Monsoon Positive 4.1 bar twin high-pressure pump driven by a continuously rated thermally protected induction motor. Designed to boost both the hot and cold water supplies to the more demanding high pressure systems the 4.1 bar twin can be used to boost water pressure to a shower, bathroom, whole flats / houses and commercial premises. Supplied ready to install the pump is fitted with a flow switch, which requires a minimum flow rate of 0.5 l/min to operate.