Loud bang when hot water comes on

[kaflinkle]

Hi all

Wondering if you anyone knows what this can be.

When my hot water comes on (set automatically at three seperate periods throughout the day, 4am, 7am and 7pm) there is a loud bang from what seems to be from a pipe upstairs. This doesn't happen all the time either and also if it does happen, it's when the central heating isn't on.

The bang happens once only but I am worried as we have had a leak before from where the banging is coming from but that was repaired by a plumber.

I have bled the radiators but it doesn't make any difference. My guess is that there is air trapped in the system but I'm no expert (I'm not even an amateur come to think of it!) so appreciate any advice before I call the plumber for another look.

My boiler is a Glowworm Ultimate and it all seems to work fine, my water's hot and the house heats up nicely. I do not know what make/model the storage tank is though.

Thanks

 

[ChrisR]

May just be the CH valve closing with a donk. See if you can MAKE it do it.

 

[kaflinkle]

That's the problem, it seems to be random so when a plumber does come over, it never happens!!

 

[kaflinkle]

I forgot to mention, it doesn't sound like it's coming from anywhere else but a pipe in the bedroom (where the hot water tank in the airing cupboard is) but I could be wrong about this.