sealed central heating system - changing taps

[eddie5081]

Hi

I have just moved in to a new flat and need to replace the kitchen sink and taps. I have a sealed central heating system and need some advice on how i isolate the hot and cold water feeds to the taps?

 

[muggles]

Your central heating system has nothing to do with the feeds to your kitchen taps. If there are no valves on the feeds to the taps, we'll need a bit more info before we can help you.

Do you have a hot water cylinder? Or is the water heated instantly by your boiler?

To turn off the cold, just turn off the stopcock, then open the kitchen tap to let the pressure out. There will still be a bit of water in the pipes, which you can catch in an ice cream tub when you cut in. The hot side depends on whether you have a cylinder or not, but as you're in a flat i'll run on the basis that you don't for now. If you don't have a cylinder you'll be on a combi boiler, and switching the stopcock off will have also shut off the hot water, so you can repeat the process you used for the cold side. If you do have a cylinder it's slightly more involved, but only a little bit.

Once you've depressurised and cut the pipes, I'd suggest putting a couple of isolation valves on the pipework, that way you can switch the water back on to the rest of the flat and carry on working on your sink.

 

[JayJay1978]

Don't forget a full bore isolation valve on the hot side.

 

[eddie5081]

I do have a cylinder with a small balck tank above it

 

[muggles]

Is there a valve on the pipe linking the outlet at the bottom of the black tank to the inlet at the bottom of the cylinder?

 

[eddie5081]

Yes - looks like a gate valve

 

[muggles]

Yes - looks like a gate valve

Good, close that, it should switch your hot water off, then you can cut the pipe and put an isolator on it.

 

[eddie5081]

I have closed it (was tight to turn), but it still lets water through. I have turned on the hot bath tap and kitchen tap .... water does slow but continues to run

 

[muggles]

Probably old and ceased then, I wouldn't force it as you may well shear the spindle. Open it up fully again, what you'll have to do is drain out your tank by leaving the taps running (with the mains switched off). When the tank's empty, you should remove the old gate valve and install a new one ready for next time. You can put the isolator on the kitchen tap feed at the same time as you do the gate valve.

 

[eddie5081]

Thanks M I will try this weekend and let you know how i get on ...... will it take long to drain the tank?

 

[muggles]

Depends on how big it is and how many taps you have, probs 5-10 mins