Been away for 4 days heating was left on low, hot water was off.
Came back today the heating had been on roughly 30mins and there is a load of water on the patio from the overflow pipe from the water tank in the loft.
Anyone got any suggestions as to what may have caused it? as it has done this before (its not a regular thing).

Cistern ball valve needs some tender loving care.

If it’s all limescaled up it will leak and your overflow will end up doing it’s job.

Either isolate the mains water supply, remove the ball valve, service and refit or just get a replacement.

Yep, ball valve. Check there no debris in the valve seat (preventing the valve from closing fully).

ours was dripping for months, worse when the heating was on as obviously water expanded.

I wouldn;t leave it – turned out the overflow outlet on ours wasn’t quite low enough and water was seeping out past a ‘not done up quite tight enough’ ball valve hole in the tank.

A wine cork jammed in should keep your patio nice and dry. 👿

Replace the washer inside the valve. You can get a ‘service kit’ for a couple of quid with the fibre washer, rubber/plastic slidey bit (technical term), and the nozzley thing.

How long should they last? As we had a new tank fitted 3 years ago.

Depends what your water’s like and how good a ball cock was installed. Our last one was cheap and didn’t last long in our very hard scaley water.

There could be more to it than the tank filler valve. If your heating system has overheating or pressure/blockage issues you could conceivably get water making it’s way back up into the tank. Best to catch it while it’s doing it and go have a look to see what’s going on. If the water on the patio or in the tank looks mucky like when you drain the system you either have this or have had it in the past leaving contamination in the tank.

Nah the water in the tank is clear. Our water is hard here, so I will get one of those service kits and see what that does.

don’t bother with a service pack – a new ball valve cost less when i fixed mine

Or a good poke might free some of the limescale and sort things. I used to live in a very hard water area and every year or two the toilet ball valve would start leaking – it was just a build up of limescale and usually cleared with a decent clean. Take it off, soak in some diluted vinegar for a bit should loosen and hard to get at limescale. Or just buy a new one – they’re only a few quid 😀

Buy 2 new ones, keep one in the loft as a spare. Cheap as chips. Dont bother trying to change the washer. Remember to get a new washer on the valve to the the pipe fitting. Its a 1/2 inch thin washer. Buy it in a pack of 10 usually, as they disintegrate when you remove it.

Cougar – Moderator Obviously not a plumber by trade

Replace the washer inside the valve. You can get a ‘service kit’ for a couple of quid with the fibre washer, rubber/plastic slidey bit (technical term), and the nozzley thing.