noisy heating system- possible leak?

[noisypipes]

In October I had a new condensing Baxi combi boiler fitted.It turned out to have a dodgy diverter valve which the manufacturers replaced.The plumbers flushed the heating system after fitting.Since then I have had banging noises which are loudest in the upstairs rooms, get worse when the system has been on for a few hours and at their worst bang for a minute, stop for 4 mins and bang again etc! The installers say it is pipe expansion but why didn't it happen with the old boiler and why does it get worse when the house has warmed up? In addition the system seems to keep getting air in it - the bathroom radiator has been bled several times and is still filling with air every 4 or 5 days! They now say that there must be a leak in my existing pipes and it isn't their problem! I can see no obvious water upstairs. Would a leak and resultant air cause this kind of banging and how would I go about locating and fixing the leak? They moved the boiler from upstairs to the Garage. Help please I'm at my wits end!

 

[ddk]

the system has NOT been properly flushed. the sound is most probably a build up of sludge in the pipework and the chemical reaction which results in the breakdown of the system produces hydrogen, which explains the air gathering in the radiator. get your plumbers back for a re-flush, or a manual flush on each radiator. also, it is worth putting some inhibitor in the system (x400 etc) of fast-cleanse to breakdown the crap in the pipes/rads

 

[gas4you]

Check what trv's you have fitted. If they have only one arrow on the valve body, it could be that the flow through them is flowing the wrong way since the boiler change.

TRV hammer will sound like a pneumatic drill when it occurs as the trv shuts.

 

[ddk]

good point, although as far as i am aware (i may be wrong here) most -if not all- modern TRV's are designed to work with water flowing in either direction.

 

[gas4you]

Yes, I agree they are, but OP hasn't mentioned trv's so the jury's still out on that one

 

[ddk]

lol yes i suppose, im new to this forum so what does OP mean?

 

[gas4you]

original poster, or original post.

Never assume anything when replying, most op's don't give full details, or often not fully accurate

 

[ddk]

cheers dave, read a few posts and you sound like you know what youre talking about

 

[gas4you]

cheers dave, read a few posts and you sound like you know what youre talking about

Far from it, I am constantly learning, the same as everyone else. I have gained as much from this forum as those I have helped

 

[ddk]

same here mate, learning every second. do you mostly install or repair?

 

[gas4you]

50/50 these days, but since the so called 'credit crunch' I am spending more time on repairs.

Can't keep up with the work load though, especially with customers who have 3-5 year old Ideals wanting them taken out and replaced

This is getting more common every week now

 

[ddk]

i agree the work is non-stop, but it will be a sad day when people like us start complaining about too much work...££££££££

 

[noisypipes]

Thanks so much for your replies!
I wasnt in when they flushed the system and fitted the valves but it didnt seem to take as long as i had been told it would and the plumber told me it wasnt very sludgey at all(despite never having been flushed). The 3 valves upstairs are fitted on the return and the 1 downstairs on the flow.i've tried removing the valves but the noise continues - if the valves were the problem would removing them stop it?They did put some chemical in the system before flushing and left it for about 5 days.I seem to remember they told me that power flushing could burst pipes in an old system and if that happened they would not be liable. Is this usual? Could flushing have caused a small leak?