Problem with cold water header tank

[Blossom]

I wonder if someone can help me please. We have had no problems with drips from the overflow and no sign of any other problem. A couple of days ago without warning we could hear water running into the tank and then water started pouring out of the overflow pipe. Unfortunately the overflow pipe couldn't take all the water and it started coming over the top of the tank and through the kitchen ceiling. The kitchen floor was covered with water. I dread to think what would have happened if we'd been out.
We've had another ball valve fitted, and up to now we've had no problems.
I'm worried it will happen again. Can anyone explain why this would suddenly happen.

Thank you.

 

[plumben]

I wonder if someone can help me please. We have had no problems with drips from the overflow and no sign of any other problem. A couple of days ago without warning we could hear water running into the tank and then water started pouring out of the overflow pipe. Unfortunately the overflow pipe couldn't take all the water and it started coming over the top of the tank and through the kitchen ceiling. The kitchen floor was covered with water. I dread to think what would have happened if we'd been out.
We've had another ball valve fitted, and up to now we've had no problems.
I'm worried it will happen again. Can anyone explain why this would suddenly happen.

Thank you.

The valve washer most likely came to the end of its life and no longer stopped the flow of water

 

[townfanjon]

Your overflow pipe should ( in most cases ) handle it. Just check it is unobstructed and flowing downhill .

 

[gassafe]

Check it's not backfilling into the tank from a faulty mixer or shower...

Check the overflow is clear as they can block up, so it does not happen again! Fit a quality ball valve like peeler!

 

[Blossom]

Thanks for the replies. The water was gushing from the overflow pipe, so it isn't blocked.
Maybe the pipe isn't big enough? The water was pouring through the ceiling.
Blossom

 

[lame plumber]

15mm feed in should have a 22mm overflow to cope with it going out.

 

[Blossom]

Thanks for your reply. The overflow pipe is only slightly bigger than the feed pipe, so we'll get it sorted.

 

[Sparkgap]

15mm feed in should have a 22mm overflow to cope with it going out.

Depends on mains pressure. Personally, I'd be happier with 32mm at least.

 

[gassafe]

What ball valve was fitted out of interest? Old style float valves tend to run slowly but the modern side entry fill valve like a fluidmaster in a header tank can fail on full blast!!
99% percent of overflows are 22mm so I guess there only capable of a small leak, not a full mains pressure load of water!

 

[Blossom]

Thanks for your reply. It was an old style float valve.