cold water header tank overflowing

[litody]

This has happened on and off for years. It only happens sometimes after I use the shower which has a direct cold water gravity feed to power shower pump from the header tank. Running hot and cold taps for short time usually stops the overflow and normality is resumed. but its a pain that it happens sometimes(and expensive if I'm not in and it runs for hours).
So I figured new ballcock. Replaced it twice and it still happens. The ballcock in the loo never over runs but that valve is a diaphragm valve whereas the header tank ballcock is not. We have very high external water pressure but I have turned house stopcock right down to reduce pressure (I think, certainly flow rate reduced)

So question is, which is the optimum type of valve to use in cold water header tank. I saw some described as high pressure but they are all ballcock so look the same. Is a diaphragm type valve better?

Thanks

 

[nickelarsed]

can you actually see water passing the ball valve when it's meant to be closed?

 

[litody]

can you actually see water passing the ball valve when it's meant to be closed?

I haven't actually been up there whilst its overflowing. Am I making a wrong assumption? There is an overflow going into tank which I guess comes from hot water system. ( Economy 7 immersion tank). No central heating. And there is the outflow to immersion tank. So I guess if that overflow was running it could cause problem. Maybe I should get up there next time its overflowing.

 

[Whn1]

Definately the could be one of many things.

 

[litody]

if it was the overflow from hot water system what would cause that to overflow?

 

[Whn1]

Could be a faulty stat/immersion

 

[Whn1]

You need to get someone in really as cylinders that boil over are very dangerous.
If that is the problem.

 

[litody]

don't think its boiling over since it wasn't on. i.e. only heats during the night when economy 7 kicks in and not in morning when I take a shower. Its after shower that the overflow happens so its something to do with refill of ho****er tank and/or header tank.

 

[nickelarsed]

there are a few possibilities. Really the thing to know is whether the water is passing by the ball valve, coming back up the distribution pipe which can happen with a split coil or mixer or is it coming out of the vent from the hw cylinder. Tough to know what's up without that information. You are probably better off getting someone in because I would bet it's not the ball valve and you'll need a plumber for most of the other situations.

And as said if it is boiling over it's dangerous

 

[Whn1]

You need to get up there when it happens.

 

[Whn1]

No coil.

 

[nickelarsed]

No coil.

oopps.

 

[litody]

thanks all. I'll report back next time it happens. Probably in the morning. I have ladder in place ready to shin up there and check it.

 

[Mike Jackson]

You need to be up there when the shower is running to see what's occurring.

 

[litody]

OK its definitely the ballcock valve not closing. So back to original question. Are diaphragm valves better at closing off than the usual ballcock type valve?

 

[Dotty]

No. You need the correct WRAS ballvalve for your tank. You may need a pressure reducing valve fitted.

Can you post a picture of the ballvalve?

 

[PlumbBobBob]

has the ballcock got a straight arm or a bent one?

 

[litody]

no photo. Arm is slightly bent. Done by me the last time I tried to fix this. Ball cock was bought for purpose from local builders merchant so should have been the correct item for the job.
Anyhow, I think I'll just get a new high pressure one, fit it and see where we are this time.

 

[wigz]

you will need a brass portsmouth ball valve bs1212, make sure you change the float aswell. cant use plastic valve on cwsc tank.

 

[litody]

reading up a bit it seems that a part2 valve is required. What is on there currently looks like a part1 valve.