Making my system quieter - corroded cylinder?

15 Apr 2005
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United Kingdom
How can I make my central heating quieter? Recently had to drain it down a couple of times, and now everytime I have the hot water or heating running, theres a loud whooshing and gurgling sound, like water is trapped in the system and being circulated.

The system comprises a system boiler at front of house in bedroom cupboard, cylinder in back bedroom - linked via pipes through loft. The pump and 3 way valve is adjacent to the cylinder. From the cylinder cupboard, the central heating pipes go down and horizontally under the floor. Above the cylinder is the header cistern.

How can I stop this noise?

And would a maintenance agreement with e.on cover 3 way valves? The rads near the cylinder get hot when the hot water is on. Or could this be causing the gurgling? All the rads have been bled.

The system is 20+ years old, when I next drain it down should I throw some inhibitor in the cistern while its filling?
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Cheers Kev. I've "bled" the pump - what should happen when I turn that screw? I got a bit of water from it. Then tightened it back up. Is the idea to remove water? Or to remove air?

I'm running it now with heating and HW on (for a test) and it seems a lot quieter and smoother - with the odd air pocket coming through. Does bleeding the pump really make this much difference? Or is it just behaving itself for the time being? Its certainly not making swooshing noises like before.

There is what looks like a drain cock in the loft, above the cylinder, but cant remember which pipe its on. Its not a bleed valve, its a drain cock, pointing upwards. Its below the cistern and abov the cylinder. I can only asume this is instead of a bleed? But why here, surely the cistern does the job of bleeding the head of the system?

update: 20 mins later and I have turned off the HW and running just the CH. There is NO air noise. Air noise only exists with HW ON. The noise appears to be coming in the main from the cylinder outlet at the bottom.

So what is causing this noise? I have bled everything I can find. Could it be an imbalance between the cylinder and the rads? There is a gate valve on the cylinder outlet.

The cylinder is an "albion supalag green 900x400 indirect (ref2)" apparently. It is showing signs of corrosion, and has leaked at the inlet and outlet holes for the heat coil, but a plumber said he wouldnt touch it with a bargepole in case he tears the cylinder. And I cant afford a new cylinder. But could this be the problem? A slightly corroded cylinder?

Pictures attached.

Cyl outlet:
Cyl inlet:
Junction at bottom of cylinder:
3 way valve:
The whole lot:

no, that isn`t the problem - or much of one either ;)
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Judging by the picture of your motorised valve, it would seem there is no vent on the h/water flow. Personally, I crack the nut going in the cylinder and release it that way.

Yours has leaked and sealed itself but any plumber worth his salt would never worry about tearing the cylinder. Worst that can happen is the washer sealing the domestic water can get dislodged and then its a PITA job. :mad:
Judging by the picture of your motorised valve, it would seem there is no vent on the h/water flow.
Ok, a couple of questions, what would this vent do? release air from the cylinder coil? Is this my problem? I realise there is no way for air to release from the cylinder at the moment because all pipes from the motorised valve go down. Is it a similar principle to a radiator bleed valve?

I would open the gate valve a bit more, its may be restricting the flow a bit to much.

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