Central heating noise

[disco_monkey79]

Apologies for the probably vague posting, but central heating maintenance is a new field for me...

We've had the heating on a lot recently (no explanation for that needed!), and we've started getting what I believe is noise from the pump. However, it's not constant. It'll rattle away, and then the noise will stop, and it'll do its thing nice and quietly. And then, with seemingly no reason, start groaning again.

If it was constant, I'd assume an airlock, or a worn pump, but I can't understand it being intermitent.

Any thoughts, anyone?

Thanks!

p.s. the noise starting and stopping doesn't coincide with the heating being turned on and off... ;-)

 

[RogerS]

Not an expert but suspect you have some trapped air in the system which gets moved around the system and then when it gets to your pump, a bit of cavitation occurs which is the noise you hear.

Either that or your pump bearing is knackered and on its' way out!

 

[disco_monkey79]

Thanks for the reply. If the air's moving round the system, then presumably I need to bleed it when it's hammering through the pump (so I know where it is). Is there generally a bleed valve at the pump?

Thanks

 

[RogerS]

I don't think it's as simple as that. You can bleed the pump if there is an airlock in it ie the water is not able to circulate at all but in your case, it sounds like the water is circulating.

This is a bit outside my area now. Why not post on AskTheTrades?

 

[laird]

Have you tried bleeding the highest radiator when the system's been off for a few hours?
Or, even better, bleed every radiator when the system's been off. This gives the air time to rise to the bleed screws - which it can't do when the pump's running.
remember you may then have to top the pressure up (if it's a closed pressure system).