Check the cut-out pressure of your water pump. Is it below the lifting pressure of the relief valve fitted to the C-Warm heater? If it’s below 2.0 bar then you can use the standard water heaters.
A water pressure of 2 bar (2kg/sq cm) is ample for most domestic purposes. Water usage is likely to increase at higher pressures. The pressure switch on a small pressurised water pump typically cuts in at about 0.7 bar (10 p.s.i.) and out at about 1.4 bar (20 p.s.i) The relief valve set to to lift at 2.5 bar remains closed.
Pumps with cut-out pressure at or above 2.5 bar can generate enough pressure to lift the relief valve, protecting the storage heater from excessive pressure but leading to continuous loss of water. If a pump cut-out pressure of 2.5 bar or more is essential, a storage heater with a higher pressure rating is required. C-Warm hihg pressure models are rated for use at pressures up to 3.5 bar (51 p.s.i.) with matching relief valves.
ON NO ACCOUNT SHOULD A HIGH PRESSURE RELIEF VALVE BE FITTED IN A STANDARD PRESSURE STORAGE HEATER