Noisey & Airy Central Heating System

[MerkyG]

Here goes and I hope this all makes sense...... I have a gas fired boiler which heats the hot water and heats the house via radiators (expansion tank in the loft) and approx once or twice a day generally when the central heating is on pipes in the loft start gurgling very loudly and this then travels down to the boiler, the only way I can stop this is to bleed 1 or 2 of the radiators upstairs (with a lot of air coming out), however within half an hour it can all start again.

To complicate things even more this morning with just the boiler on heating the hot water tank (central heating off) the noises started again and I had to bleed one of the radiators 4 times (each time I'd done it the problem was solved only for it to start again!), even though the central heating was off!

I've emptied the system on a number of occasions whilst I've been diying, removing radiators etc. I've cleaned the system out then put inhibitor in. The last time I did this was about 2 weeks ago and the noises stopped for about a week, unfortunately to return. One point to note is the water tends to run pretty clean when I drain the system but when I take any radiator off the water is black and full of gunk!

I have a baby on the way in a few months and need to keep noises like this to a minimum.

Look forward to hearing from anyone who can shed some light

Regards
Mark

 

[Softus]

You might well have added inhibitor, but this won't negate a dirty system, so if you had sludge and rust then it will still be there.

One common problem with sludge in systems is that it can lead to sufficient blockage(s) to cause air to be drawn down the open vent. From the information you've given so far, this is quite likely to be happening. (FYI this can also [sometimes] happen with a clean system that's been incorrectly plumbed).

If you can keep your system limping along until the cold weather abates, then I would do that. Then you need to drain down and flush out as many radiators as you can.

A tip - before your next drain down, go into the loft with a good light, shut off the cold feed to the F&E cistern, bale out all of the water in it, then sponge it out with clean water so it's clean of all debris. If you emerge with filthy brown hands then it will have been worth doing; if clean hands then not.

Blocked cold feeds are very common, so the idea of this is to prevent further debris being drawn down the cold feed, that would prevent water from entering the system.

 

[namsag]

When it`s making this noise is there very hot water spurting into your header tank and are the rads a lot hotter to the touch than they used to be.. If so your boiler thermostat may have gone

 

[Softus]

When it`s making this noise is there very hot water spurting into your header tank and are the rads a lot hotter to the touch than they used to be.. If so your boiler thermostat may have gone

Hm, maybe, but are you saying that this is sole cause of the problems? If so, how do you account for the radiator water being "black and full of gunk"?

 

[namsag]

No not the sole problem . Just dealing with what sounds like the boiling up problem.

 

[MerkyG]

No not the sole problem . Just dealing with what sounds like the boiling up problem.

To be honest it happens so quickly that I haven't been up into the loft to see what occurs when it all 'kicks off' as its over by the time I've openened the hatch and got the ladder down and got up there. I will however leave the ladder down tonight and rush up there when it starts. How would this spurting account for 'alot' of air to be blead out of the radiator

 

[MerkyG]

You might well have added inhibitor, but this won't negate a dirty system, so if you had sludge and rust then it will still be there.

One common problem with sludge in systems is that it can lead to sufficient blockage(s) to cause air to be drawn down the open vent. From the information you've given so far, this is quite likely to be happening. (FYI this can also [sometimes] happen with a clean system that's been incorrectly plumbed).

If you can keep your system limping along until the cold weather abates, then I would do that. Then you need to drain down and flush out as many radiators as you can.

A tip - before your next drain down, go into the loft with a good light, shut off the cold feed to the F&E cistern, bale out all of the water in it, then sponge it out with clean water so it's clean of all debris. If you emerge with filthy brown hands then it will have been worth doing; if clean hands then not.

Blocked cold feeds are very common, so the idea of this is to prevent further debris being drawn down the cold feed, that would prevent water from entering the system.

Thanks for your comments, very helpful thanks. When draining down and flushing out the radiators would it be best to remove each radiator individually and flush each one out? However is the corrosion and sludge likley to be from the radiators rather than the pipes. A hose would no doubt clean out a radiator but how about the pipes?

 

[Softus]

How would this spurting account for 'alot' of air to be blead out of the radiator

A system that's pumping over, or boiling over, regularly draws water in from the F&E cistern. Because of the water exiting the vent pipe this water is freshly oxygenated, and readily leads to internal corrosion of the radiators and, if ferrous, of the boiler's heat exchanger(s).

In case you hadn't already realised, this is A Bad Thing.

When draining down and flushing out the radiators would it be best to remove each radiator individually and flush each one out?

Yes.

However is the corrosion and sludge likley to be from the radiators rather than the pipes.

Yes, unless you have iron pipes, which is rather unlikely.

A hose would no doubt clean out a radiator but how about the pipes?

You catch on quickly!

The sludge can settle in the pipes, but mostly it doesn't. Once you've cleaned out the radiators and reinstalled them, add a cleanser to the system and leave in for long enough to dissolve/dislodge any resident sludge and rust. Fernox and Sentinel both manufacture excellent cleansing products.

At this stage I should draw your attention to the risk involved here. If you clean out a system that's heavily corroded, and I'm not saying that yours is, you can expose latent leaks. If you go this route then be prepared to have to replace any radiators that spring leaks in the next few months. This is why it's best done in the spring.

 

[MerkyG]

No not the sole problem . Just dealing with what sounds like the boiling up problem.

To be honest it happens so quickly that I haven't been up into the loft to see what occurs when it all 'kicks off' as its over by the time I've openened the hatch and got the ladder down and got up there. I will however leave the ladder down tonight and rush up there when it starts. How would this spurting account for 'alot' of air to be blead out of the radiator

When the noises started again last night I raced into the loft and found mainly air plus a bit of watering spluttering into the F&E tank via the feed pipe, which I guess suggests that yes it is air in the system and I need to de-sludge each rad once it warms up a bit