Central heating noise query

rubyrose

Hi

My central heating is a back boiler behind a gas fire, cold water tank in loft and hot water in airing cupboard.

For the past week or so there has been a really loud gravelly noise coming from the loft for about 10 seconds (seems like longer!) when it's turned on in the morning and once in the evening. It's not every time the heating goes on, just once a day normally. My heating has been on for a few weeks now and it's only started recently, we've always had the loud banging noise from the pipes but this has now started to happen. Judging from a bit of internet research it may be kettling? How serious is this? I'm trying to find a decent plumber to come out but finding one with a good reputation takes time!

Thank you

RubyRose

cyclonebri1

rubyrose wrote: »

Hi

My central heating is a back boiler behind a gas fire, cold water tank in loft and hot water in airing cupboard.

For the past week or so there has been a really loud gravelly noise coming from the loft for about 10 seconds (seems like longer!) when it's turned on in the morning and once in the evening. It's not every time the heating goes on, just once a day normally. My heating has been on for a few weeks now and it's only started recently, we've always had the loud banging noise from the pipes but this has now started to happen. Judging from a bit of internet research it may be kettling? How serious is this? I'm trying to find a decent plumber to come out but finding one with a good reputation takes time!

Thank you

RubyRose

It's kettling:D:D

I call it cavitation or some call it air inclusion.

There is air somewhere in the system, needs bleeding out but how did it get in???, which will be the next question , ;)

"finding one with a good reputation takes time",, :eek::eek::eek::eek:;);) sorry chaps,

Mr_Ted

Its probably NOT kettling from what you say in respect of now and in the past

Kettling usually occurs when the system is warmed up or at its set temperature!

Its a common problem with Back Boilers that have a cast Iron heat exchanger that when they fire up initially and they are sludged the water due to the sludge doesnt heat very well throughout initially as it is thicker and due to this it doesnt circulate very well.

This is what causes the banging, which basically is thermal shock, and this often, due to poor initial circulation as the pump often cant cope initailly, causes the water to be unevenly heated and the water that is getting hot and expands will push either back up the cold feed or out of the open vent, which is the gravelly noise

It is possible you MAY get air in the system, but basically the system needs flushing, particularly the boiler, as the sludge will lay there as the system cools as it is a low point

ValHaller

If the noise is coming from the loft, it is probably an overflow into the header tank

plumb1_2

I would go with post No3

ValHaller

plumb1 wrote: »

I would go with post No3

Even if as OP says, the noise comes from the loft?

macman

First thing to do is get up in the loft and check the header tank. You don't need a plumber or RGI for that.
OP, if it's a boiler issue, you need a GSR RGI, not a plumber.

plumb1_2

ValHaller wrote: »

Even if as OP says, the noise comes from the loft?

Yes. as it only happens when turned on. Water being shoved up, vent/feed.
Kettling will happen all the time the boiler is on, not just the secs the OP states.

The Op needs to get in the loft, and get someone to turn the heating on, and see whats happening .