Rafal Kaczynski
Hi Barnaby This is one of the main causes of faults in pressure reducing valves. It is best to fit special devices to absorb water hammer when installing pressure reducers in at-risk systems. Trouble-shooting Certain types of fault, which are generally due to faulty design of the system, are often wrongly attributed to pressure reducing valves. The most frequent cases are as follows: 1. Increased downstream pressure in the presence of a water heater This problem is due to heating of the water caused by the water heater. There is not relief of the pressure because the reducing valve is rightly closed. The solution is to install an expansion vessel (between the heater and the reducer) to “absorb” the pressure increase. 2. The reducer does not maintain its calibrated value In most cases this is the result of impurities that deposit on the valve seat causing leakage with a resulting increase in pressure downstream. The solution is to fit a strainer upstream of the reducer and subsequently to maintain and clean the extractable cartridge Proceed as follows for periodic cleanting of the strainer and inspection or replacement of the cartridge: 1 Shut off the reducer 2 Unscrew (anticlockwise) the calibrating screw to decompress the spring inside. 3 Unscrew the cover. 4 Extract the cartridge with the aid of pincers to grip the head of the screw. 5 The cartridge can be fitted back into the valve after inspection and cleaning or alternatively a replacement cartridge can be fitted. 6 Recalibrate the reducer. I hope this will help Best regards Raf
