Cold water tank emptying

[David Crook]

I'm a total novice with plumbing so need some help. My cold water tank has been on constant refill so looked up causes and saw folk recommending replacing washers in the ballcock arm. Did that but still wants to run all the time. When I switch off the water supply to the cold water tank, it's draining at about 5mm per minute. No idea where the water is going, the toilet cisterns are working ok but central heating now playing up so wondering if there's a leak somewhere underground between the house and the boiler in the garage. No visible sign of anything.
Any ideas what's going on?

 

[Newboy]

If you're losing water at that rate then there either is a leak somewhere or you have an appliance using water.

Do your toilet cisterns have internal overflows? If so then check that they are not constantly flowing into the pan.

central heating now playing up

In what way?

 

[David Crook]

We have a wood pellet boiler out in the garage. Normally the water temperature in the boiler is about 72 degress but not getting much above 60 and not providing a full batch of water. Normally enough for a couple of good long showers, currently barely enough for one.

 

[JohnD]

So you probably have a leak on a hot water pipe. Or a tap left running.

 

[bernardgreen]

but central heating now playing up

but not getting much above 60 and not providing a full batch of water.

Is the tank in the loft the tank that supplies cold water to taps and to the hot water system. or is it a header tank for the central heating water that flows around the radiators.

If it is a header tank then a leak on the central heating system ( radiators, pipes etc ) could prevent the boiler reaching its normal 72 degs with heat being taken away in the leaking water.