Noisy central heating

[chard]

Hi Ive noticed an increase of noise over the last few days.

The system is quite old (30-40 yrs at a guess) gas fired. Two radiators in the attic conversion are microbore the rest is conventional.

I noticed one of the attic rads was not getting hot so have tried to bleed it. A lot of air came out (hissing) and now it's getting warm but even with the bleed screw removed no water coming out of the hole. Tried the other attic rad this ones also warm (not hot) same thing no water coming out with the bleed screw removed.

The header tank is about 18 inchs above the top of the attic rads.

Could the increased noise be air in the system or am I on the wrong track. The noise sounds a bit like the pump (this was replaced 5 years ago)

Edited by chard on Monday 24th January 07:31

[dirkgently]

At a guess if there is water in the cistern you have a blocked cold feed from the f/e cistern to the boiler and the water level is getting low.Unfortunately it is a PITA to fix as it usually entails cutting the pipe at low level, cleaning our and rejoining pipe.

[chard]

Thanks. I've bled the air out now (system turned off)seems a bit better.

[sherman]

Have you ever flushed out your system. It is probably pretty full of gunk.

[chard]

This thought had occurred to me. Messy job, kinda putting it off.

[sherman]

It is messy but find out where your central heating outlet pipe comes out of the house. It may be in an area of the garden that you can let get covered in mucky water and then either a quick brush or hose down will clean it all up.

[Globs]

sherman said:

It is messy but find out where your central heating outlet pipe comes out of the house. It may be in an area of the garden that you can let get covered in mucky water and then either a quick brush or hose down will clean it all up.

Never heard of this.

I did however modify my central heating when I found that despite fernox that my tank feed had silted up and could not flush the system. I put a stop-tap between the water mains and the CH header tank, and a gate valve to the header tank. Now I can flush the system with full pressure mains water by turning two taps

I still have to connect a hose to a drain-off point and into the garden however.

[sherman]

There is an outlet near the ground on my house. Looks like a hose pipe tap with no handle on top. Its on the 3rd or 4th course of brick up from the ground.

[Ricky_M]

A power flush can totally transform a heating system. Its a pricey job, but you'll stuggle to match the results by draining and refilling a few times.

I did one today on a 30 year old heating system, each radiator was too hot to touch and the boiler had stopped kettling.

If you are pretty handy at DIY, you can rent the machines for around £60 a day. Sludge remover and inhibitor are probably around £30-£40.

A power flush will not unblock a blocked pipe though, so if the feed pipe is blocked, you'll need to get that sorted first.