Overflow

[goo283b]

Please can you help?


I have a cold water tank in my flat from which after a period of time (8hours +) water starts to run out of the overflow. If I flush the loo or turn the tap on it stops. Surely it can’t be the ball cock because it would do this as soon as the tank was full?

It happens mostly overnight when water is not being used so I assumed that it was some kind of pressure. A few years ago the thermostat on the heater overloaded and boiled the water so a new thermostat was put in which does not heat the water over 65 degrees. I don’t think this has failed because I cannot see evidence of overheated water etc.

This doesn’t happen every day. It has happened about three times over the past 2 weeks and prior to that the last time was when we all went away overnight, which was a couple of years ago. In the past I have also seen my bathroom taps drip at night but not in the daytime.

 

[breezer]

it over flows because the tank is full.

sometimes (probably always) the overflow outlet is an inch or so above the stop point for the ball cock, but if the ballcock does not seal / stop properly it will drip, the drips take some time to fill the tank to the overflow height. you need a new ball cock assembly or a new washer.

take the lid off you loo cistern and see how high above the stop filling level the overflow outlet is , i bet is an inch or so

 

[Softus]

I have a cold water tank in my flat from which after a period of time (8hours +) water starts to run out of the overflow.

That's because there's too much water in it.

If I flush the loo or turn the tap on it stops.

That's because there's no longer too much water in it.

Surely it can't be the ball cock because it would do this as soon as the tank was full?

I don't understand your reasoning. It's either the float valve (aka ball cock) or a faulty mixer valve in your bathroom/shower.

It happens mostly overnight when water is not being used so I assumed that it was some kind of pressure.

Wrong assumption. Almost all assumptions about plumbing turn out to be wrong. I think it's because people assume things that they want to believe, rather than deduce things that are real.

A few years ago the thermostat on the heater overloaded and boiled the water so a new thermostat was put in which does not heat the water over 65 degrees. I don't think this has failed because I cannot see evidence of overheated water etc.

I don't think that's relevant to your overflowing water situation.

This doesn't happen every day. It has happened about three times over the past 2 weeks and prior to that the last time was when we all went away overnight, which was a couple of years ago.

That doesn't indicate which of the two possible causes it is.

The easiest way to diagnose it is to inspect the cistern when it's overflowing. If the water is stone cold and the float valve dripping, then replace the float valve. If the water is warm, tepid, or even hot, then you need to start the search for the faulty mixer valve.

In the past I have also seen my bathroom taps drip at night but not in the daytime.

Is that because you're at work in the daytime?

 

[goo283b]

Hi Breezer,
Yes I can see that but why would it take 8 hours and happen somedays but not others? Its also a slow run not a drip

 

[Softus]

you need a new ball cock assembly or a new washer.

Not so fast - put down that adjustable wrench and back off. You haven't diagnosed the fault yet. (Although, as you and I know, that's par for the course with you.)

take the lid off you loo cistern and see how high above the stop filling level the overflow outlet is , i bet is an inch or so

What in blue blazes are you wittering on about?

goo283b - please ignore this nincompoop. You need to get into the loft, not the bathroom.

 

[breezer]

goo283b, incase you were wondering why i said take the cistern loo lid off to look, its becuse its easier than looking in the loft to find that i am right. (about the differance between over flow outlet and stop filling water level)

8 hour differnce is becuse (probably) the water demand is less at night than during the day.

 

[goo283b]

I hope I haven't started a fight

 

[Softus]

goo283b, incase you were wondering why i said take the cistern loo lid off to look, its becuse its easier than looking in the loft to find that i am right.

Kindly stop misleading the OP with irrelevant nonsense about the toilet cistern.

 

[breezer]

goo283b, its up to you if you want to look in the loft or in the loo cistern, but the loo cistern is probably easier to look in

 

[goo283b]

Breezer,
I am confused now but I think I may have confused you both.

goo283b, incase you were wondering why i said take the cistern loo lid off to look, its becuse its easier than looking in the loft to find that i am right. (about the differance between over flow outlet and stop filling water level)

The cistern in the loo is fine. The overflow is from the cold water tank which is upwards of about 5 foot high (over the hot water tank) in the cupboard next to my bathroom. The overflow pipe comes through the wall and over the bath.

[/quote] 8 hour differnce is becuse (probably) the water demand is less at night than during the day.

Thats what I had been told but can you explain why the less water demand would do this?

 

[goo283b]

Sorry Softus,
That was meant for you too

 

[Softus]

I am confused now but I think I may have confused you both.

The only thing that's confusing me is how breezer could possibly think that he's helping.

The overflow is from the cold water tank which is upwards of about 5 foot high (over the hot water tank) in the cupboard next to my bathroom. The overflow pipe comes through the wall and over the bath.

In that case you need to look in the the cupboard rather than the loft, but you still need to do what I recommended in my first post.

...can you explain why the less water demand would do this?

If you draw water off from the cistern faster than the faulty fill rate, then it won't overflow, and vice versa. Most people don't draw off any stored water at night.

 

[breezer]

goo283b, i am not confused, you just did not follow what i meant.

i know its your loft coldwater tank that is overflowing (you said so) I merly pointed out that there is a similarity between your loo cistern and loft water tank in relation to the position of the overflow outlet (they are both about an inch (at least) above where the water should stop.

I also meant that if you lift the loo cistern lid off you will see what i am refering to.

as very little water is used at night the pressure is "slightly higher" in the pipes so the valve will leak (its only "slightly Higer" becuse people are not using water during the night, so the water that is available goes up slighly in pressure)

 

[Softus]

goo283b, i am not confused, you just did not follow what i meant.

That's because it was utterly irrelevant.

i know its your loft coldwater tank that is overflowing (you said so)

No he didn't. It isn't in the loft.

I merly pointed out that there is a similarity between your loo cistern and loft water tank in relation to the position of the overflow outlet (they are both about an inch (at least) above where the water should stop.

It's completely irrelevant.

 

[goo283b]

Yes I am begining to see what you mean.

Seeing as I live in a flat and the water must come from some type of communial mains does the use or non use of water in my neighbours flat contribute to the change in my water pressure?

Until I get this fixed will it become worse i.e. will the water flow become more rapid?

My plumbing knowledge goes as far as unblocking the u bend and putting a new loo ball cock in so I am extremely greatful for all your help.