Water Tank Overflowing but not ball cock

[Alex Needs Help!]

Hi,

I have a problem and would be grateful for any help. At the weekend, when filling up the bath, the overflow pipe from the roof started chucking out water.

I have one tank in the loft. I have changed the ball cock already but have realised this isn't what's causing the overflow.

When running just the cold tap or just the hot tap the tank doesn't overflow. However, if i run the cold and hot taps (mixer tap) on the bath simultaneously the tank fills and overflows. The water isn't coming from the ball cock's valve but is coming IN from the pipe at the bottom of the tank where it is meant to come out of!

Furthermore, the water is literally just dribbling out of the cold tap and is absolutely flying out of the hot tap! PS. I have a combi-boiler.

I'm presuming the hot water pressure is somehow overpowering the cold and this may be the problem? Also there is a fair amount of debris in the tank (although water is clear) that could have got into the pipework.

Any advice would be greatly appreciated.

Thanks

AL

 

[ShaunCorbs]

Are you sure you have a combi boiler ??

 

[Alex Needs Help!]

Are you sure you have a combi boiler ??

Definitely - It's a Vaillant ecotec plus 831

 

[ShaunCorbs]

Well there's your problem you shouldn't have a tank

As it's mains pressure hot I'm guessing a shower is passing and the hot water is going up the tank cold

 

[Alex Needs Help!]

Well there's your problem you shouldn't have a tank

As it's mains pressure hot I'm guessing a shower is passing and the hot water is going up the tank cold

The shower doesn't seem to impact it. We have lived here for 2 years and it has been fine up until now. I remember when it was installed he said he left it on the tank because it had better pressure?

 

[ShaunCorbs]

The shower doesn't seem to impact it. We have lived here for 2 years and it has been fine up until now. I remember when it was installed he said he left it on the tank because it had better pressure?

Easy way to tell run any mixer outlets and see if the tank water becomes warm

And unless the tank is 20m above all the outlets the main water going to win

 

[Riley]

What a load of rubbish. Love what crud some engineers spout

 

[Alex Needs Help!]

Thanks everyone. Sounds like the only resolution is going to be to get a plumber in to put he it onto the mains. Does anyone know if this is a big job? e.g. roughly how much £ should i expect to have to lay out?

Thanks

 

[Ric2013]

We are all assuming the bath filler is a mixer. Is this correct, OP?