Cold water tank valve problem

[diydazzler]

I have a cold water tank in the bathroom.The other day I noticed water coming out of the overflow so went out and bought a new valve and float.
Bent the arm to the same angle as the old one and fitted it.
Turned the water back on and the tank filled to about 2 or 3 inches below the overflow and the valve appeared to shut off.
On saturday there was the sound of water surging and then stopping repeatedly coming form the tank as it refilled after running a bath.
This morning I see a damp patch on the ground below the overflow.Had a look in the tank and the water level is above the overflow outlet and the float is submerged completely.

Faulty valve ?

 

[jeff the gasman]

It could be a perforated coil in the hot water cylinder. Run some water off and check if the valve has a positive shut off manually.
Jeff

 

[diydazzler]

Yeh the new valve appears to be working.
The header tank for the central heating has an overflow pipe that drops into the cold tank but that appears to be dry,but then again I'm not using the heating

 

[stardanny]

Try a test you can do:

Fill the tank as normal, turn off incoming main to both cold water storage and heating tank a few hours before going to bed.

In the morning, check if the water level in cold water storage tank is same or higher and the heating level same or lower.

If the cold water storage is higher, you have a hole on coil in cylinder.

Make sure the new valve is working and not letting by.

Do you have a mixer tap in kitchen?

Daniel.

 

[diydazzler]

Try a test you can do:

Fill the tank as normal, turn off incoming main to both cold water storage and heating tank a few hours before going to bed.

In the morning, check if the water level in cold water storage tank is same or higher and the heating level same or lower.

If the cold water storage is higher, you have a hole on coil in cylinder.

Make sure the new valve is working and not letting by.

Do you have a mixer tap in kitchen?

Daniel.

Yes I do.
I don't know whether this has anything to do with it but I've had low pressure from the hot tap in the kitchen for a number of years.Upstairs taps are fine.
The central heating header tank is a bit of a bugger to access as it's in the loft

 

[diydazzler]

Pretty sure it's the central heating header tank ball valve that's the problem.
Cheers

 

[stardanny]

The header tank for the central heating has an overflow pipe that drops into the cold tank

The overflow from header tank should really go to outside like other overflow for cold water tank.
Dirty water from header tank overflowing into cold, clean water for bath, washing is not good.

Daniel.