Hot cylinder valve only moves about a 1/4 turn, safe?

[Cheeeseman]

I changed my kitchen taps, there were no isolation valves to make my life easy, so I turned off the mains stopcock, and the red valve on the hot water cylinder before starting.

The new taps are in place and no leaks, but I notice the red valve (photographed) next to the hot water cylinder only moves about a quarter turn. I can't be 100% certain it only moved that much to close it when I started but I'm fairly sure. Is that something to worry about, is it safe? Would it make the boiler explode or what have you if it was stuck near closed


The gas central heating works, and the water out of the hot taps is hot and at the usual pressure. It's a really old boiler, with a big open tank in the loft and separate hot water clyinder. If it sounds like I'm not too clued up on these things, it's because I'm not!

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• Cheeeseman
• 10 Oct 2012
• 1

 

[Burnerman]

Thats a gate valve, and it could be a good idea to expose a bit more of that pipe work and trace where its going to.....
These things are multi turn, and can be used as a pipe isolator (likely) or even a central heating bypass. If it only moved a quarter of a turn, then I guess its stuck.
Presumably when you worked on your taps, you closed the main stopcock and then drained the loft tank down to allow work on the hot tap?
John

 

[Cheeeseman]

Oh, a reply! Dancer!

To change the taps, first I turned off the mains stopcock, then ran the cold taps till they emptied, then turned off all the electrics, then the electrical switch next to the hot water cylinder (there is also an separately switched electric hot water immerser that is never used you see) then turned the red knob that's giving me anxiety attacks, then ran the hot tap till it emptied.

Then I fitted the new taps, thanks largely to my new basin wrench, turned all the knobs back and electrics on, then started worrying about the red knob

What do you think, safety wise? Should I be worrying? I know the water you wash you hands with is not the same filthy stuff in the radiators, but I do worry about things I don't really understand, could it be starving the boiler of water to boil, or something

 

[Burnerman]

Valves like these are often used to regulate the water supply from the tanks in the loft that feed the copper hot water cylinder, for example.
They mustn't be used in such a situation that renders the system unsafe therefore I think that you are worrying needlessly because if the valve was turned off then one or more of the taps wouldn't be working now.
If this valve allows cold water into the bottom of the copper cylinder to be heated - and say you turned it off - then the hot water output would also be restricted, if you catch my drift....it wouldn't allow the copper cylinder to run dry.
If the valve is used as a central heating bypass, this allows the boiler to circulate hot water back to itself if the radiators are turned off, but you say all is well there.
As before, if you could lose some of that insulation and trace the route of the pipes concerned, that could be handy - or let someone else take a look for you.....as I said earlier, these valves need a few turns from off to fully on - a quarter of a turn would make little difference.
Try to remember just how much you turned it....my guess is that it was fully turned on, and the quarter turn you gave it was simply taking up the slack in the screw mechanism.
John

 

[Cheeeseman]

Thanks Burnerman, I really appreciate your advice.

The cylinder is wrapped in 2 layers of insulation, and the outer layer is that really nasty yellow fibreglass, so I'm going to put off checking where the red knob pipe leads till tomorrow. It's near the top of the cylinder, and leads up I guess to the loft.

If it turns out I'm worrying over nothing and making a big fool of myself, that's a relief The radiators are working properly, and all the hot water taps too. So maybe it was stuck on all the time after all? I've read horror stories about seized gate valves snapping and don't want to risk messing the thing up.

 

[Burnerman]

Here's a guess, Monsieur le Fromage......that valve (which really belongs in the Fred Dibnah era) will probably be in the pipe that leads from the tank in the loft to the bottom of the copper cylinder......in which case it should be fully open.
Worry ye not.....
John

 

[Cheeeseman]

You're the man!

I checked the valved pipe today and it does seem to lead from up the loft to the bottom of the cylinder.

I had a brainwave when I first turned the valve to close it, after I closed the cold mains stopcock, it still took 15 minutes for the hot water taps to drain off.

Taking so long, does that mean the 1/4 turned "closed" valve was probably nothing off the sort, and it took that long because the entire tank in the loft had to drain off?