Mains water inlet valve

[Mr-H]

My mains water inlet valve (tap under the sink as opposed to stopcock in the street) is stuck, presumably with limescale 'cos we live in a vary hard water area. Brute force could break the tap, any ideas what I can use?

[ELVIS68]

Spray it with WD-40 and leave it for an hour

[Clanad]

Before applying the WD-40 ala Elvis.. do this: Take a Zip-top storage bag big enough to fit over the handle in question. Using some typical duct type tape secure the bag and then pour common white vinegar into the bag. The vinegar should cover the valve... especially the stem from the handle through the bonnet nut on top of the valve. Leave it in that condition for a couple of days, remove the bag and vinegar, then apply some WD-40 and a little force with a pair of what we call Water Pump pliers here in the U.S. They look like this: http://img2.timeinc.net/toh/i/a/tools/pliers-0 2.jpg

Now, very gently begin to move the handle... wiggling it back and forth in order to break loose the scale holding the shaft.

Here in the U.S. most shut=off valves look like the ones in this discussion link: http://www.askmehelpdesk.com/plumbing/replacin g-shutoff-valve-under-bathroom-sink-200523.htm l

Notice the nut under the handle on the shaft. Here, it's called the bonnet nut. If you absolutely can't loosen the shaft, then try loosening this nut slightly and then turning the handle. In any of these attempts, be sure you know where the main shut=off valve is for the whole house coming from the street and that its moveable... Best of luck!

[Malagabob333]

If a British standard S/V and If above fails, locate packing gland nut.situated around shaft.Loosen 1or 2 turns(anticlockwise)and as above gently rock shaft back and forth with grips.If this fails and you are confident and you have access to a plumbers torch(after moving all flammable items from under sink and protecting nearbye surfaces) gently warm the body of the S/V for 20-30 seconds.Repeat process,warming and gently rocking.

[gazzawazza]

The answers above may be difficult to try if your is in a difficult position like mine is, (at arms length below and behind kitchen units!)
If so, you could try a simpler method first which I had to use once. Just soak a cloth in hot water, (the hotter the better, but not so you're going to scald yourself) and then lightly wring the cloth out and quickly wrap it round the stopcock body and leave it for a few minutes. Gently try the valve and it may turn, at least it did in my case!

[danchip]

i used cillit bang on mine with great results