Turning off mains water

slystallone

I had a look under my kitchen sink to see if there is something to turn off the water but found nothing. However this is just outside the house at the same location...could it be this could help me? Also what kind of tool would I need here to get down to it.

Shoog

https://www.boards.ie/discussion/2058361666/turning-off-mains-water

That's a stopcock. You need a stopcock tool with a square head to turn it - they are standard enough and can be got from any decent hardware store (forget the big box stores).

slystallone

https://www.boards.ie/discussion/comment/122432498#Comment_122432498

When I turn off the water with this tool, I want to change a tap in the house. Should I turn on the taps on one of the sinks inside after turning stopcock and let all the water leave the system?

Shoog

https://www.boards.ie/discussion/comment/122432537#Comment_122432537

There should be very little pressure in the line. You can turn on the main cold kitchen tap to drain the last bit.

This stopcock only isolates the the kitchen cold tap in an open system so if you are working on any other tap you will need to drain the header tank in the loft. This can be done by opening all taps in the whole of the house.

slystallone

https://www.boards.ie/discussion/comment/122432672#Comment_122432672

If I am changing a bathroom tap do I need to turn off the mains at the outside then? There appears to be no valve on the hot and cold pipe going into the sink on which I intend to change the tap

Shoog

https://www.boards.ie/discussion/comment/122432714#Comment_122432714

I would put some isolation tails into the lines, again they can be bought from a decent hardware store. This allows you to change out taps in the future simply by turning a screw rather than draining the system.

Those taps will be fed from the loft tank so the loft tank needs draining in the way I described. There are other ways of doing it but all involved getting into the loft and finding an isolation tap for the header tank or tying up the ballcock.

slystallone

https://www.boards.ie/discussion/comment/122432752#Comment_122432752

It is a mixer tap so would both taps be from the loft tank? Thought hot water be from the cylinder?

Doolittle51

Draining the whole tank in the loft is a last resort when changing a tap. Usually there are isolation valves in the hot press, and in fact it looks like there might be one under your sink? Have you tried turning that off? In the absence of isolation valves, I'd bung the outlet pipes on the tank rather than drain it down. Draining the loft tank can cause more issues, like airlocks and introduce dirt into the system.

slystallone

https://www.boards.ie/discussion/comment/122433970#Comment_122433970

Tried it but seemed to do nothing

patspost

My own experience has taught me not to do plumbing when the HW shops are closed, in case supplies are needed.

slystallone

https://www.boards.ie/discussion/comment/122433970#Comment_122433970

Here is my hot press. Can you identify the isolation valve locations?

slystallone

https://www.boards.ie/discussion/comment/122433970#Comment_122433970

What is the the best way to bung them?

Shoog

https://www.boards.ie/discussion/comment/122434082#Comment_122434082

Expect to get very wet with this approach.

Doolittle51

Red lever valve on the left looks like it might be on the supply pipe to the bottom of the hot water tank? if so, that'll isolate the hot water. Lever valve at the front could be the isolation valve for cold water, but I can't tell from just a picture of course.

You can buy rubber bungs specifically designed for the purpose In the past I've improvised using a conical plastic door stop inside the finger of a rubber glove 🤣

Doolittle51

https://www.boards.ie/discussion/comment/122434126#Comment_122434126

Why so?

Shoog

https://www.boards.ie/discussion/comment/122434146#Comment_122434146

Thats always been my personal experience whenever I have been foolish enough to try it

Doolittle51

Might be best to stay away from plumbing so. Pretty fool proof tbh:

https://www.lenehans.ie/rubber-plug-drain-down-avoidance.html?gad_source=1&gclid=Cj0KCQjwtZK1BhDuARIsAAy2Vzth3JElq-vaXUa71fx0ZoFI0WnEEbhX1dJun-cd5M_SL19hYBjsmlAaAnmNEALw_wcB

Shoog

https://www.boards.ie/discussion/comment/122434184#Comment_122434184

I plumbed most of my house so I don't think I will follow that advise.

Draining down is fairly foolproof and any airlocks are relatively straighforward to clear in a hot cold water system. Not so much in central heating.

If you manage to isolate in the hot press you still need to drain down the pipes before starting work.

slystallone

What size tap spanner should I use here?

The Continental Op

Pair of mole grips and snap it off. Nothing you can see there is going to unscrew easily. Although the threaded rod the nuts are on will probably unscrew from the monoblock itself.

I have a set of these which I'd use https://www.amazon.co.uk/Rothenberger-80000-Monoblock-Tap-Spanner/dp/B0020281RK/ although I tend to reach for these long handled mole grips first https://www.amazon.co.uk/Long-Nose-Reach-Locking-Pliers/dp/B007P606LK/

slystallone

https://www.boards.ie/discussion/comment/122434139#Comment_122434139

When I have the header tank drained, and I close the valve on the supply pipe to the bottom of the hot water tank, can I then just start disconnecting the hot water pipe going into the mixer tap back at the sink straight away or do I have to do another step first, I am thinking maybe I have to drain the hot water also?

Doolittle51

No, once there is no supply into the hot water tank, nothing can come out, so isolating the supply to the hot water tank is sufficient. Then when you open the hot tap at the sink, there will still be some water in the pipes, which will drain out. Depending on the pipework configuration, it'll probably help if you open all other hot water taps in the house too. When turning the water back on, leaving the hot taps open will help prevent airlocks. There will be a lot of spluttering, so best not to open them too much.

Did you identify any valve for isolating the cold water feed to the tap?

slystallone

https://www.boards.ie/discussion/comment/122451528#Comment_122451528

No.

Also when closing the hot water valve mentioned earlier and I open the tap, what exactly am I draining? Is it whatever remains in the cylinder? Or something else?

slystallone

What does the gate valve at bottom right hand side of cylinder do?

Doolittle51

https://www.boards.ie/discussion/comment/122453824#Comment_122453824

You're just draining the water in the pipes, there won't be much. The red gate valve is a balancing valve for the hot water coil, which is associated with your boiler & heating system. Don't adjust it, as it can unbalance your heating system.

If you're not confident about isolating the water, it might be best to get a plumber or handyman to change the tap for you. Wouldn't take them any more than 30 minutes.

slystallone

https://www.boards.ie/discussion/comment/122454128#Comment_122454128

I have the hot water tap in the kitchen running now for an age and it's still dribbling away, the upstairs bathroom hot tap is fully dry and the non electric shower downstairs has a small dribble too on the hot side. By what you said I thought it would be a few minutes max for water to drain out? Could the water in those 2 mixer taps that are still dribbling still have water coming out after 30 minutes even though that hot water valve is closed?

Doolittle51

The valve could be passing a bit, giving you a constant dribble.

slystallone

https://www.boards.ie/discussion/comment/122432752#Comment_122432752

And once I drain the header tank there will be neither hot nor cold water going to that mixer tap?

slystallone

...

Shoog

https://www.boards.ie/discussion/comment/122609845#Comment_122609845

There shouldn't be anything coming to that mixer tap.

slystallone

Once I drain the tank in the loft can I just take off the tap then or do I have to still close some valves near the cylinder before starting?

Shoog

Once the tap stops running you can simply disconnect it. There will likely be a small bit of water in the pipe which will spill but it's going to be collectable on a towel.