rattling pipes

[Mark D. Smith]

Hi

we have a combi boiler that was fitted over a year ago and the whole system had a power flush. now all the rads work well and have their own thermostats.

recently the pipes upstairs are driving me nuts at bedtime by rattling at random intervals.

is this air blocks?

Mark

[Phil Anthropist]

Assuming that this noise is caused by air trapped in the pipes to the upstairs radiators, and not from hot or cold water pipes (water hammer) to the upstairs sink and bath, and not from expansion and contraction of pipes and rads, you could try turning off all the downstairs rad valves, fully open all the upstairs rad valves, and just run the upstairs rads for a while in case this forces the air out. It would also be worth checking to see if there is any air in any of the rads that needs bleeding out. If this problem persists, and is due to trapped air, the cause of air entry needs to be found and fixed.

[Mark D. Smith]

Hi

i don't think its water hammer as we are not using the sink or bath upstairs when this happens. will try your suggestions

Mark

[EricP]

When you say "rattling", do you mean a metallic tapping noise, very quick?

[Mark D. Smith]

Yes and No. i used plastic pipe fixers to separate and hold down the pipes when i had the floors up and it has been quite for around 6 months, its just the last few weeks that we have seen an increase in the noise (which yes you could describe as "metallic tapping noise, very quick?"

Mark

[EricP]

Next time it happens, see if it comes from the thermostatic rad valves. The valve seat is bouncing, causing the hammering effect. The valve makes the noise but it is amplified by the radiator and sounds like it is the whole rad that is making the noise.

Could be that the warmer weather has altered the flow through the valves and caused the noise.

Come back if you can say that it is the thermostatic valves.

[Chris R]

Often it's a thermostatic valve mounted the wrong way round/on the wrong end of the rad.

Chris R