Hammering water pipes

[bradmac]

Hi

I have a baxi 105e combi boiler, and after the heating has been on for about an hour 1/2 the pipes start hammering.
The pressure is ok and the heating works fine could someone help me please

 

[JPC]

hammering ?

can you desc.

its not hot pipes expanding and creaking against the joists underfoot ?

 

[bradmac]

cheers for the reply
would it take that long for the pipes to warm up?
i will check it out and see

 

[bradmac]

sorry

the pipes start to bang (hammering sound) but it is ok for about an hour 1/2 then it starts, it didnt happen when we had our old boiler, but with this one it does

 

[kevplumb]

do you have trv's fitted

 

[bradmac]

yes but they are old ones

 

[kevplumb]

boiler flow and return are reversed

 

[bradmac]

sorry to sound stupid but what does that mean

 

[jobloggs]

Old TRV's only suitable for flow in one direction through them. Most new ones are bidirectional.

What previous post is suggesting is that when new boiler was fitted the direction of flow through the system was reversed perhaps. Old TRVs are noisy if you reverse the flow through them.

 

[bradmac]

would it take an hour and a half for the banging to happen - or would it happen straight away ? (by the way thank for all your help)

 

[corgiman]

could take a while to happen as the TRV may need heating up to expand to the point where they starting throbbing

have u tried turning them down when its banging and see if that stops it? if it does you have your answer

 

[garethgas]

Alternatively, take all the heads off....if no more banging it'll be one of the heads.

 

[bradmac]

i turned off trv's and the banging stopped (need to get new trvs then)
thanks very much for you help