C-WARM Temperature & Pressure Relief Valve 3 BAR RATED ONLY for use with C-Warm Water Storage Heaters This item only fits units manufactured since 2003 Check that your marine pressurised water pump has a pressure switch set to cut out at or below 2.5 bar (36psi). Use of a switch cutting out at or close to 3 bar (44psi) could lead to continuous discharge of water through the relief valve.