Noise in central heating pipes

[jonprior]

I have a gas central heating system that functions perfectly as far as heat is concerned. However, the two radiators at the back of the house (ground and first floor) cause a loud humming to come from the pipes nearby when they are turned on. If I reduce the flow through the radiators, the noise decreases proportionally. The only way to get no noise at all is to close the valves on both radiators.

I have bled the radiators and tried all sorts of combinations of on/off/partially open valves on these radiators. I thought it might be the pump, but this is on its lowest setting.

I have just moved into the house, and the noise wakes me up too early in the morning! The only alternative is a freezing cold bathroom; does anyone have any ideas?

 

[awilkins]

No help but plenty of sympathy - I have an almost identical problem except that my radiators click.
I'm pretty sure it is not expansion because this happens well before any tangible heating up occurs.
I also tried bleeding them to no effect.
All I can add is that if I try moving the balancing valve it starts leaking water after half a turn.
So it's a wake up call at 05:30 or a cold bedroom.
Good luck !

 

[AnonymousImport]

Look for a by-pass valve near the pump. If there is a manual one, it's probably closed to much. If it's an automatic one, the pressure setting needs to be lowered. If not fitted at all you can add one in if you're handy with plumbing. Honeywell make a good automatic one - type DU145, available from plumbers merchants. They work by maintaining a constant pressure at the radiators, regardless of how many radiators or on at the time. They are almost obligatory if you have thermostaic radiator valves (TRVs on your radiators.

See link below for more info:

http://content.honeywell.com/uk/homes/files/pag102.pdf

 

[jonprior]

Thanks; have confirmed there is no bypass valve, but also no trv's at all. I have lifted floorboards and checked all piping is secure; any further ideas?

 

[awilkins]

I've not looked for a bypass valve yet but I now think that it is down to expansion noise afterall.
Some previous occupant has plastered a lot of the pipes into the walls nice & tight and there are some pipes rubbing against each other.

Thanks for the bypass valve idea

 

[mark]

what is a bypass valve,please?

 

[breezer]

in this case it is a valve that automatically by passes the pump,as the author said "They work by maintaining a constant pressure at the radiators, regardless of how many radiators or on at the time"

I found this on search engine but you will need acrobat reader