CH header tank overflowing when system is cold

lesalanos

I had the same problem last year when I started the heating again. The problem was as above, the ball valve was leaking

jpscloud

OK guys... in the night I got up to go to the loo but had left the loft hatch open. I could hear water trickling so when I got up I went and had a look - it is trickling from the cold water tank pipe that goes into the CH header tank.

It stops as soon as I run water and as long as water is being run through the day, it doesn't start again (I was out a lot yesterday so no water being run).

I'd be really grateful if anyone can give me a rough idea of the possible horrors that await in expenses to sort that out?

Is your hat safe Keystone?

jpscloud

lesalanos wrote: »

I had the same problem last year when I started the heating again. The problem was as above, the ball valve was leaking

I found out this morning the water is overflowing from the cold water storage tank, next to the CH header tank. It is coming from the ball valve outlet on the cold water storage tank, but I am not sure if it is the valve that is faulty because it stops when water is run. To be fair, the ball valve system on the cold water storage tank is very creaky and old, though.

It also stops when the central heating/hot water gas boiler is put on.

I don't understand why it's happening but here is a summary of the events which seem to have caused it:

I turned off the gas CH/hot water a few weeks ago. I started to use the immersion heater (only ever used once in a blue moon before, used maybe once or twice a week now).

The water started to overflow from the cold water tank overnight, when everything was cold.

It starts again if I don't run water. It has increased from a slow drip to a fast drip to a trickle.

I think I might have to try putting the gas boiler on again twice a day to see if that stops the problem altogether. If it does, what could that mean? (Apart from not as much money saving as I would like!)

Grateful as ever for advice!

southcoastrgi

Well first (& cheapest) get the ballvalve changed hopefully this will sort it, where are the two tanks positioned with regard to each other ie are they both sat on the same piece of wood or is the smaller tank higher ?

jpscloud

The two tanks are at the same height. If it was the ballvalve, wouldn't it run constantly though?

I'm most worried about the hot water tank needing to be replaced and hoping that isn't the case, as even the call out charge to replace a ballvalve is beyond me at the moment.

southcoastrgi

Ok if the coil in the cylinder had started leaking then the water in the two tanks would try to find their own level, eg the top of the big tank is higher than the header tank so with nothing running & no water going into them via the ballvalve the header tank would overflow as the water tries to get to the height of the water in the storage tank so if that is not happening then it's not a leaking coil, yes sometimes the ballvalves will leak it will be worse at nite as the incoming pressure increases due to not many people using the supply, try & find a plumber with no call out charge or at least one that inc the first hr within it, a part 2 ballvalve should cost you no more than £10 & a plumber no more than £40 to do it, like I have said it is a diy job as long as you turn the mains off, I know you can't do it yourself but do you not know any friendly neighbours or friends that could help you out if money is tight.

keystone

jpscloud wrote: »

it is trickling from the cold water tank pipe that goes into the CH header tank.

Are you saying the the CWST overflow discharges into the F&E tank?

It stops as soon as I run water and as long as water is being run through the day, it doesn't start again (I was out a lot yesterday so no water being run).

As you draw water from the CSWT the level drops. The valve opens to allow more water in to refresh the level in the tank. There comes a point when the valve should shut off. If its passing only a little bit some time will elapse before the water level reaches the overflow and then (if I've read it properly) discharges into the F&E tank which then also slowly fills up until it overflows. That would account for the time lag.

Is your hat safe Keystone?

At the moment yes I think it is. Inlet (ball) valve on the Cold Water Storage (CWST) tank is the first port of call.

Cheers

keystone

jpscloud wrote: »

It also stops when the central heating/hot water gas boiler is put on.

The purpose of the Feed and Expansion (F&E) tank (or CH Header Tank if you will) is to provide feedwater for the heating system and primary circuit (the pipework that goes from the boiler through the coill in the HW cylinder and then back to the boiler). It keeps the heating system topped up. There will be losses in a system of your age and the level will drop in that tank as the heating is on. It stops dripping because the level in the tank will fall. If the ball valve for the F&E tank is sound which it is by all accounts when that operates to refill the F&E tank it only fills it to a certain level before it shuts off. From what you have described then when you stop drawing water from the CWST the cycle repeats itself. CWST overflows into the F&E tank and the drip starts again.

I turned off the gas CH/hot water a few weeks ago. I started to use the immersion heater (only ever used once in a blue moon before, used maybe once or twice a week now).

The water started to overflow from the cold water tank overnight, when everything was cold.

It starts again if I don't run water. It has increased from a slow drip to a fast drip to a trickle.

I hope my explanation above helps.

Cheers

keystone

jpscloud wrote: »

The two tanks are at the same height. If it was the ballvalve, wouldn't it run constantly though?

Not in my 'umble opinion. See above. If the CWST valve as passing at a prodigious rate then yes it would though.

I'm most worried about the hot water tank needing to be replaced and hoping that isn't the case, as even the call out charge to replace a ballvalve is beyond me at the moment.

Please see my contribution yesterday earlier up the thread.

There are two other ways that water gets into either tank.

Both have a vent pipe (U shaped piece of copper pipe 22mm or 3/4 inch depensing on how old your system is.) pointing down into their respective tanks.

These allow for expansion of water in the system. If the vent pipe over the F&E tank is producing steam or hot water when the heating is on then the system is doing what is called "pumping over". Thats an entirely different issue to your inlet valve problem.

If the vent pipe over the CWST is producing steam or even hot water when the DHW system is in operation there are two causes. First the coil in the HW cylinder is perforated/ruptured and hot water from the boiler is being pumped into the cylinder, up the vent and into the CWST. If this is not occuring then your cylinder is fine and you should stop worrying about it. The other time it can happen is if the thermostat in the immersion heater has failed in which case the contents of the cylinder get heated to boiling point, the hot water steam expands up the venyt an over into the CWST. If this is not happening when you have DHW in operation then there is no problem.

I still don't have to buy a new hat yet. Inlet valve on the CWST remains my favourite cause.

Cheers

jpscloud

southcoastrgi wrote: »

Ok if the coil in the cylinder had started leaking then the water in the two tanks would try to find their own level, eg the top of the big tank is higher than the header tank so with nothing running & no water going into them via the ballvalve the header tank would overflow as the water tries to get to the height of the water in the storage tank so if that is not happening then it's not a leaking coil, yes sometimes the ballvalves will leak it will be worse at nite as the incoming pressure increases due to not many people using the supply, try & find a plumber with no call out charge or at least one that inc the first hr within it, a part 2 ballvalve should cost you no more than £10 & a plumber no more than £40 to do it, like I have said it is a diy job as long as you turn the mains off, I know you can't do it yourself but do you not know any friendly neighbours or friends that could help you out if money is tight.

I wish there was a double, huge, love-you-forever thanks for the both of you! I have the sort of brain that loses the ability to function when confronted with words like "vent", "Pipe", "valve" in any sentence involving physics. Thank you for the really helpful explanations. :T

keystone wrote: »

I still don't have to buy a new hat yet. Inlet valve on the CWST remains my favourite cause.
Cheers

I can't quote all the really helpful stuff you've written because it would make this post too long, but thank you thank you thank you for your patience and perseverence with my blithering. Even if you turned out to be wrong (very unlikely) I would buy you a new hat just for putting up with me!

You are both :A :A

:T:T:T