Getting water hammer when motorised 2 port Honeywell turns hot water off to the cylinder. Valve works fine and its the right way. System been in for years and its just started happing. Boiler pump keeps running which is correct to dissipate the heat but as soon as the hive turns the hot water off i get water hammer. Should there be a ABV installed ? But it’s been working fine for years. (Its like once the hive gives the signal to shut the valve it should stay open for few minutes to let boiler pump finish but it shuts straight off)
