How do I replace the gate valve (without flooding my attic)?

[gutt3d]

I've recently bought a new house, and trying to get to grips with the plumbing and heating. I've got 3 header tanks in the attic - a small one which I guess is for the CH, and 2 much larger ones which both drain to the same place - they drain to the hot water tank in the airing cupboard.

The large header tanks are both fed from the mains cold feed (although the pressure is very low, it seems), and are both more or less directly above the hot water tank. Each of these 2 large tanks has a gate valve.

We discovered this evening that one of the gate valves is stuck closed. One header tank had drained completely, while the other one is completely full - I tried to open the gate valve on the full tank, but the wheel and spindle just turn without doing anything.

I guess I need to repair the valve, but the problem is it's currently holding a completely full header tank of water at bay. I can't drain the tank, as the valve is knackered - is there some cunning way to repair the valve without draining the tank, or do I need to use a washing up bowl to empty the "stuck" tank, and turn on the hot taps to drain the other (working) one?

Cheers,
Dan.

 

[keego]

Bung the outlet from inside the tank & change the valve, you can buy a set of bungs from any plumbers merchants or B&Q.

 

[thefloosyonthebeach]

syphon it out or bung it. simples.

 

[seco services]

you can bung the outlet in the tank to the gate valve then you can remove the gate valve complete and replace.

bq or any plumbers merchants do pipe bungs.

 

[gutt3d]

Bungs - that sounds promising... I was thinking about plugging the inside of the tank somehow, but if there's some sort of gadget that is made for the purpose, tthat would be ideal!

If I go to B&Q or a plumbers merchant and ask for "a set of bungs for my header tank" they'd know what I mean...? Is there a special name for them, or are they called exactly that: a set of bungs for the header tank?

Sounds like it might be a bit easier than I thought - fantastic!

Thanks for the advice - very much appreciated!

 

[gutt3d]

you can bung the outlet in the tank to the gate valve then you can remove the gate valve complete and replace.

bq or any plumbers merchants do pipe bungs.

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Excellent! Thank you very much - that looks to be just the job!!

I'll get to B&Q tomorrow after work!

 

[Bahco]

If both tanks are feeding the cylinder ensure that water enters through 1 tank and exits the other. You will get stagnation otherwise.

Shouldn't need 2 tanks anyway!

 

[seco services]

If both tanks are feeding the cylinder ensure that water enters through 1 tank and exits the other. You will get stagnation otherwise.

not if they are both fed by their own ball valve.

Shouldn't need 2 tanks anyway!

depends how large they are and what else the tanks supply.

 

[Razor900]

I'd stick my finger inside the outlet first to make sure it's smooth and theres no splines inside or bungs won't work in which case turn the mains off and drain it into the bath using a hosepipe.

Even if you can bung it it's gonna need flushing through if the waters been in there for a while time to get a chlorination kit methinks

 

[gutt3d]

Sorted - thanks again for everyone for the help. The bungs made the job possible, but didn't completely seal the outlet pipe... I had to force the bung in place, and hold it there while I swapped the gate valve over - I only lost about a quarter of a washing-up bowl from the tank. But without the bung, I'd never had been able to do it - everything would have gotten soaked!

Undoing the nuts was hard work though, and in the event I must have dislodged a seal at the bottom of the header tank. When I put it all back together, the PTFE either side of my new gate valve was dry as a bone - but there was a steady drip from the bottom of the tank. Had to drain it, after all, to re-seal the outlet pipe.

Meantime - the reason why there are 2 tanks, I think, is because the mains pressure is so low: we have a pump to give us decent pressure at the taps and shower, but a single tank can't refill quick enough. We've got 2 tanks so that there's enough water for at least 2 showers (back to back) without running empty. We actually found out that the gate valve was blocked when we had 2 showers and the pump shut down part way through the second shower...

Each tanks has its own ball valve. There's a gate valve on each tank, and the 2 gates valves share a common pipe between the 2 tanks - with both valves open, I guess the levels in each tank should be equalised. (Then there's a second outlet on one of the tanks to fill the hot water tank).

Anyway - gate valve replaced, all stagnant water drained so I could fix the leak, and leak now fixed. Job's a good 'un.

Thanks all!