Banging pipes and a noisy pump!

[saintgeorge]

Can anyone help? My CH/HW system seems to be playing up. When it comes on, the pump in the airing cupboard makes rather more noise than it used to (a sort of gritty gurgling noise) and every so often the pipes make a pretty firm banging sound, particularly initially. The radiators don't heat up very well, if at all, and hot water is, er, not very hot. I think this is partly because the boiler seems to turn itself off within a minute or two of firing up.

Boiler, control unit, and 3 thermostats (boiler, HW tank, room) all seem to be working OK. The problem occurs when all stats are turned up to full. It also occurs irrespective of whether CH or HW is calling for heat. Control unit and thermostats call the boiler and pump OK (ie they come on when they're supposed to). Boiler last serviced May 2005, and motor on 3-way valve replaced 8 months ago.

I wondered whether the banging noise is just heat expansion, but it is more noticeable than it used to me, so I think it might be a symptom of something else.

Any ideas welcome!!!

 

[hi-spec plumbing heating]

sounds like pump on it's last legs.
check the f/e tank in the loft for water level. (small tank)

 

[doyle]

sounds like your being haunted by kirsk submarina's, i would ring kgb straight away and tell them your receiveing more code messages, they will install you a pollonium system from chenobal.

 

[saintgeorge]

Dear Hi-Spec

Thanks for that. I'd certainly thought the pump might be the suspect.

Being a novice, not sure though what f/e stands for...? And what water level should the water in the tank be at? Presumably 3/4 full wouldn't be a problem?

Any further help appreciated!

 

[hi-spec plumbing heating]

Dear Hi-Spec

Thanks for that. I'd certainly thought the pump might be the suspect.

Being a novice, not sure though what f/e stands for...? And what water level should the water in the tank be at? Presumably 3/4 full wouldn't be a problem?

Any further help appreciated!

feed / exspansion

long as the water is few inchs above the outlet.

the pump is air free i take it.

 

[Malc C]

Ours also makes a loud bang when the pump first kicks in. However I'm also experiencing issues with circulation and balancing, and in another thread the suggestions I've had indicate an air lock or blockage.

I've got a plumber coming round tonight with a view to replacing the radiator circuit as its so old

 

[saintgeorge]

Thanks both. I'll check the tank though I think it is probably OK (glanced at it a few weeks ago while messing around in the roof...)

I realise air might be a problem too though again radiators were bled last spring so not convinced this is an issue this time round.

Given that the problem is common to both HW and CH (tepid shower this morning despite 1 hour of HW control unit calling) I am rather suspecting the pump. The boiler decides to turn itself off after no more than 2-3 minutes of heating so it clearly thinks something isn't right.

 

[hi-spec plumbing heating]

sounds like the pump.
as the boiler not running for long as pump isn't pulling the hot water away.

 

[saintgeorge]

OK. I'm going to attempt a replacement of the pump - I am wondering whether the bearings inside have given up.