hi guys,

just got called out to a job this evening, 4 other plumbers have been prior to me...this has been going on for a year!

its a mains pressure h j cooper hot water cylinder that makes a banging noise randomly, its a very loud bang that you can hear all through the house,

 i was sent by apex to replace the cold water expansion valve, I isolated the two ball valves either side of the cwe at the inlet to the cylinder, opened up the lever on the cwe to relieve the pressure and the bang went off like a shotgun, then the drain oin the cold water expansion felt hot.


is there anyway it could be a issue with the tempering valve non return? the take off line on the cwe does go up to the tempering valve,

from what the customers have told me ALL the valves (including the limiting valve in the garage ) have been repaced

the customers are starting to get frustrated.....

Linkback: https://www.plumbers.nz/plumbing/1/h-j-cooper-cylinder-banging/2358/

I have had this issue before. It will be a faulty element ARCING under water.

hi guys, yeah very strange, i suppose expansion and contraction could let a drop or two in then seal before arcing but i imagine that the element would slightly `faulty`from new, long shot but.... cheers

How loud is that banging noise if the element has a crack? Is it unmistakable? I'm having a paranoia that I'm hearing something like that.