Tank Overflowing - Please help!

[Sal831]

Hi Can someone please help with some advice. Our cold water storage tank is constantly overflowing, regardless of whether the boiler is on or off. If the mains water is switched off, it doesn't overflow, but within half an hour of the mains being on, it is overflowing again.

The ball valve has been replaced.

Also the header tank (which doesn't have an overflow) seems to have hot water in it....is this normal?

Is there any easy way of testing if the coil has gone, as I know this can cause this kind of problem.

We are worrying that it may be something to do with the new bathroom that we have had fitted. But everything in the bathroom seems to be functioning normally, but have been told that it may be caused by a mixer tap being fitted incorrectly, again an ideas on how to test this theory??

Thanks

SM

 

[75pete]

New bathroom with a mixer.........Isolate the mixer tap then check the tank.

If your mixer does not have isolators then fit.

This is the first thing to do before looking to fit a new hot water cylinder.

Put in a overflow.........simple diy

 

[TonyW2]

Before panic and costs set in, that replacement ball valve may be the simple source of your problem.

Check it is working OK and that the ball arm has actually been adjusted to cut off the feed before the tank fills upto the overflow.

If that does not cure it, can we have more details of your c/h & h/w system. Is it pumped or gravity?
Is the mixer cold supply from the tank or direct from main?

 

[Sal831]

Thanks,

Will triple check the ball valve, but don't think it is due to this as it does seem to be working correctly.

The system is pumped and the cold supply to the taps is from the mains, hot water from the tank in the loft.

Cheers

Sal

 

[TonyW2]

OK.
Then can you turn off the cold supply to the mixer at any point? (If not there is a more complicated way to test it, but it will involve two people!)
Does this stop the "overflow"? If so was the mixer a "cheapo"?

 

[seco services]

as 75pete has already said its a mixer tap issue.

you've had a new ball valve fitted.
faulty ball valves don't let hot water into the cws tank.

 

[TonyW2]

The hot water is said to be entering the header (feed/expansion) tank--presumably the one for the c/h, --not the cws.

 

[seco services]

The hot water is said to be entering the header (feed/expansion) tank--presumably the one for the c/h, --not the cws.

yes i agree reading it again it would appear he has two issues.

 

[Sal831]

Thanks guys,

So you think that I have two seperate issues then? One causing the overflow and one causing the water in the header tank for the central heating to be hot?

You are right in the fact that I can turn off the mains to stop the cold water flow to the mixer and this in turn does stop the overflow. So I think we have found the problem with the overflow.

So any ideas as to why the header tank for the radiators is heating up??

-Sal

 

[TonyW2]

Yes there are seperate issues, but the fact that turning off the mains stops the overflow has not yet determined the source of the overflow problem.
You need to have the mains supply to the mixer turned off, whilst the mains supply to the store tank is on, so that the problem can be traced to either the mixer or the ball valve! If in that situation, the overflow continues, it is the ball valve. If you cannot turn off just the supply to the mixer, you need to tie-up or hold up the tank valve ball, so that the supply into it is definately stopped and then check whether it still overflows due to a supply getting in via the mixer.

Then you can go onto sort out the mixer or modify its supply, if needed.
Meanwhile the hot water in the expansion tank is not an urgent problem
It would be best to get the mixer confirmed before working on the cause of this problem.

 

[Sal831]

Brilliant, thanks for the help, we don't have a way to turn off the supply to the mixer only and so I will try tying the ball valve up and report back.

-Sal

 

[seco services]

Brilliant, thanks for the help, we don't have a way to turn off the supply to the mixer only and so I will try tying the ball valve up and report back.

-Sal

if you run the hot on the mixer so the pipe is hot, then turn it off does the hot pipe to mixer go cold quick ? if yes its passing cold to hot on that mixer.

all so is the pipe feeding the bottom of the cylinder from the cws tank hot ? that'll be where the hot water is rising up to the cws.

 

[TonyW2]

[quote
all so is the pipe feeding the bottom of the cylinder from the cws tank hot ? that'll be where the hot water is rising up to the cws.[/quote]

Can we just confirm that it is not the cold water tank that is getting hot water into it, but the central heating feed/expansion(smaller) tank

 

[seco services]

yes we can confirm that issue.

but the issue with the mixer tap cold bypassing to hot will push hot water up the cylinder supply pipe. (providing the cylinder is up to temp) to a certain extent. as in normal situation it will be stone cold.

 

[Sal831]

Hi guys,

Here's the update. This evening I turned off the boiler, hot water and c/h. Left the mains water on, tied up the ball cock in the cws tank (definately isn't leaking) and waited. The cws slowly filled, you can see a disturbance at the bottom of the tank where the water is flowing into it.

I then took a look at our mixer taps and it seems that we do have separate isolaters for the taps. We have 3 mixer taps in the house, the kitchen tap, the bathroom sink and the shower. Only two out of the three are easily accessible. So I isolated the mains supply to each of the two that I could get to, but still the tank continued to fill. The only one left is the shower, which will have to wait until another day as I will have to dismantle the bath to get to it (not a big job I know, but its late in the day).

So before I take the bathroom apart Is there anything else I should check?

Incidently, I don't think its relevant to the problem but just in case, it seems the ball cock in the c/h header tank is leaking just a small drip at a time and when we had a plumber come round he isolated the header tank by turning off the stop cock. He never turned it back on, and I hadn't realised, and so the system has been functioning for the last week like that. (It has been overflowing for the last 3 weeks).

Anymore ideas, or can I safely assume that it is the shower mixer? Another plumber that I was chatting to suggested it may be due to the divertor valve in the cylinder and yet another suggested a perforated coil, but seeing as the water continues to rise when the c/h and hot water is off, im not convinced.

Any further comments would be gratefully received as this is driving my housemate and I mad!

-Sally