Problem with ballcock in cold water tank

kevandkeira

Hi, hope someone can help.....

We have an old back boiler system, today whilst the heating was on the overflow from the cold water tank in the loft starting throwing alot of water out, I turned the heating straight off & that seems to have stopped the flow of water.
OH is at work but usually he would go in the loft & wriggle the ballcock around as a temporary fix, he'd then purchase & fit a new float arm & that would fix the problem.

But.........

This is happening yearly, is it normal that they would need replacing so often??

southcoastrgi

When the system isn't working the water level should be about 1 inch above the outlet at the bottom, if from that level it still overflows then you have another problem, but try lowering the water level first

alumende27

kevandkeira wrote: »

This is happening yearly, is it normal that they would need replacing so often??

I can't answer the other part of your question but no. They should last for years if correctly fitted.

Wookey

If this is the small feed and expansion cistern then there are a number of possible causes, as southcoasts says to high a storage level in the tank, rapid expansion caused my boiling water within the system most likely caused by to big a fire at the back boiler and not enough heat dissapation to use up the excess hot water being produced, the hot water pump pumping over due to to many radiators being turned of combined with hot water expansion.

If the float is needing replaced regularly then it is either leaking and allowing water into itself thereby decreasing its ability to float, if its the arm he is replacing then a lot of modern ballcocks are made with alloy and not brass which is not as easily bent to adjust the water level height and tends to snap when bent. Look for a ballcock that has an adjustable end on it which allows the float to be adjusted easily.

kevandkeira

Wookey wrote: »

If this is the small feed and expansion cistern then there are a number of possible causes, as southcoasts says to high a storage level in the tank, rapid expansion caused my boiling water within the system most likely caused by to big a fire at the back boiler and not enough heat dissapation to use up the excess hot water being produced, the hot water pump pumping over due to to many radiators being turned of combined with hot water expansion.

If the float is needing replaced regularly then it is either leaking and allowing water into itself thereby decreasing its ability to float, if its the arm he is replacing then a lot of modern ballcocks are made with alloy and not brass which is not as easily bent to adjust the water level height and tends to snap when bent. Look for a ballcock that has an adjustable end on it which allows the float to be adjusted easily.

Thank you for the replies, surely all of the mentioned possible causes would be ongoing problems though & not fixed just by changing the arm??

I can't remember exactly which arm he buys, could be either of these....
http://www.screwfix.com/p/float-valve-part-2/92516 or http://www.screwfix.com/p/pegler-float-valve-part-2/27627

southcoastrgi

What the height of the water in the tank ?

kevandkeira

OH didn't go up in the loft tonight, got in from work pretty late. I've just left the heating/hot water off for now, luckily its not too cold!!
I'll let you know as soon as he's been up there.
Thank you

kevandkeira

I would check myself but once I'm up there I cant get back down again :rotfl:

Apodemus

If you are repeatedly replacing the ball valve fittings, one possibility is that the header tank is getting very hot from the expansion flow from your back boiler. In some situations this can cause early failure of one or other of the valve components. Even if the whole tank is not getting hot, it could be that the expansion inflow is positioned in such a way that the boiling water is in contact with some of the ball-valve components.

HHarry

Following on from Wookey's idea....

If the float is faulty it could be filling up with water. Change the valve, re-use the float (whch empties when it is removed) and a year later the float is full again.
Try a new valve and flat?