Filling the header tank makes a foghorn noise

BillyWillySilly

BillyWillySilly

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I have previously isolated the feed to the header tank in the past when working on the system, rather than isolating it in the header tank itself. I just noticed after draining some water via the magnetic cleaner that the feed makes an almighty foghorn noise. The vibration is fairly extreme to the point where the isolation valve appears wet afterwards.

My plan has been to switch off the boiler and then isolate the feed itself. In this case I wanted to reassure myself that the header feed was indeed the header feed so after a couple of jugs of dirty system water, I turned the isolation valve back on and the foghorn began. It continued for about 10 seconds before tapering off.

I'm about to do a lot of work on the system and wondered if this isolation valve is a point of failure, or even whether I'm doing this right?
 
It is a very common problem, you could replace the washer but as the cost is minimal we always just replace the complete fitting.

Andy
 
It is quickest and easiest to swap the entire valve.

having done that, however, if you enjoy tinkering, you can repair the old valve with a new washer, and perhaps cone, split-pin and other wearing parts. You can do it on the kitchen table with plenty of light, no time pressure, and all your tools readily to hand. This is much easier than working in a loft, bent double round the roofing timbers, with freezing fingers and inadequate lighting. You can then give it a clean, put it in a plastic bag, and hang it up next to the cistern where it will be easy to swap back next time the valve gets noisy.

I don't know how long a brass ballcock lasts, if you re-washer it every ten or twenty years. At least 50 years, I think.
 
This isolation valve.....is it a stopcock brass type or is it a screwdriver turned Balofix one?
If its the former, replace the washer in there - although they are usually quiet when fully on.
John :)
 
Burnerman said:
This isolation valve.....is it a stopcock brass type or is it a screwdriver turned Balofix one?
If its the former, replace the washer in there - although they are usually quiet when fully on.
John :)
Click to expand...
Should I really replace this with a gate valve / new isolation valve? Been reading that the high pressure may be a problem for the stop cock?
 
Definitely not a gate valve - these belong in the days of steam where a rubber washer would vaporise :p however an in line full bore lever type valve would be fine.
Easier to replace the washer in the stopcock though, there wouldn't be any issues with pressure.
John :)
 
Stopcock came out manky covered in black nonsense. The washer seemed ok but I decided to replace the tap part completely. The compression fittings were not moving and I don't think it was worth it for me to be hitting them with hammers to free it up if the tap and washers change worked and it appeared to do so. Real test will be when I drain the system down later for a rad removal...

Thank for the advice!
 
BillyWillySilly said:
For educational purposes, what's the issue with a gate valve? Just picked up a replacement stopcock from screwfix. Let the mayhem begin...
Click to expand...
The gate valve works on a sluice principle.....when you turn the valve off, a gate descends down a guide until the water supply is fully blocked. In reality, the gate valve will still pass water if there is a blockage preventing the gate from fully descending or the gate is a loose fit in its guide. The benefits is that there is no rubber washer to wear or split, and when fully on the supply runs full bore. Often oil tanks had a gate valve to turn them off as a rubber washer would be destroyed.
The lever arm valves use a nylon seal around a stainless steel ball which are generally fairly fool proof so long as you fit them the right way round.
John :)
 
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