Category:Plumbing Question:water hammering in zone valve- boiler system Full Description:hi i had a new hot water boiler system installed im my home i have three zone valves one for the upper unit one for the middle unit one for the lower unit ( apartments) the zone valve for the upper unit water hammers when the zone valve shuts off i replace the zone valve plus i installed a arrester to eliminate the air plus i have a grundfos pump on my boiler which has three speeds low medium high i tryed each setting and i still have the water hammering I am real desperate for a solution, cannot get any sleep!!!!!!!!!!!!The noise is directly under our bed.....Richard can you please help me out, no-one else to turn to. Respond ASAP to my email. E-mail Address:badboyleafs@hotmail.com Name:Jim Style & Age of House:multiplex - originally built in 1926