Header Tank Overflow 2

[All Mod Cons]

Hi,

Can anyone tell me, if, other than the ballcock valve in the header tank, there is any other way that water can come into the system?

In investigating a problem with my header tank constantly overflowing (see other recent thread), I have tied up the ballcock and even placed a container underneath it in the header tank - so I can be doubly sure that no water is getting in this way.
Yet, when I checked the tank after the heating went off last night it was well below the overflow pipe. I even empited some more water out to take the level to just a couple of inces above the normal outlet pipe.....

... when I came in form work this afternoon (note that boiler and pump have been off all day) and checked the level, it was back up to the overflow pipe and pouring out of the overflow.
It had not come out of the ballcock valve and the container I placed under this was bone dry.
I've empited bucketloads of water out this tank over the last few days, yet still it keeps filling up from somewhere.

I'm confused as to where this water comes into the system as I thought the header tank was always the starting point. Could it come in from anywhere else?
Thanks,
Richard.

 

[ProffesorPlumb]

Its obviuosly coming back up from your HWC cold feed. Is there any other connection to this feed pipe? Or a mains cold teed into your hot water distribution pipe somewhere? Silly as it may sound......

 

[All Mod Cons]

I don't think so but i'll have to check the pipework. Is this a liklely possibility?.
Maybe I need to callout a local plumber to check into this.
I was just tryting to rule out all the obvious stuff first - but it's a really confusing problem.

 

[kes36]

Do you have a feed and expansion tank for your heating? if so, is the tank sited above your storage cistern?, if it is it could possibly be a slit or pinhole in your coil.
Do you have a shower mixer with mains cold water and tank hot water?

 

[All Mod Cons]

I don't have a feed and expansion tank, however i do have shower mixer that takes water from the hot water tank, however I think the cold comes from the cold water tank rather than the mains supply. Do you think the problem could be there?

I wondered if the coil inside the hot water tank could be perforated and then water inside the tank could be feeding (under pressure) back into the hot water system pipes. Do you think this is a possibility?
thanks.

 

[cabbadge]

Firstly do you have gas fired central heating? if not then your cylinder is unlikely to have a coil. if so then you must have an f&e tank. unless you have an unvented system then in which case the tank you can see is your f&e tank or do you have a combi in which case you dont have a cylinder i will be able to answer your question better if i know which system you have.

Just To Correct Myself That It Is Possible To Have A Coil Without Gas Fired Central Heating

 

[All Mod Cons]

Yes, it's a gas fired boiler with a hot water tank containing a coil. Yes I do have an F+E tank which has a vent pipe above it.

Thanks,
Richard

 

[cabbadge]

Then it seems that the coil must be split therefore pushing the water from the f&e tank into the cold water storage cistern through gravity to test this and be absolouty sure turn off the water supply to the f&e tank to see if the water disapears from the f&e tank. If so then im affraid a new hot water cylinder is needed.

if the cold water storage tank is lower than the f&e the stop the supply to that tank instead to see if that water disapears.

*sorry If The Cold Water Tank Is Higher

 

[All Mod Cons]

Thanks,
Yes, that's what isuspected after reading various forums etc.
I've bought a new H/W tank and am going to fit it today. The system is draining down as i type. Will let you know if this fixes it. Fingers crossed as the tank, new fittings & immersion cost me £200.

 

[All Mod Cons]

Hi - here's the update to anyone who may have similar symptoms.....

I changed the hot water tank and the problem is solved !!! Hoorah !!

Yes, I guess as I thought and some people suggested, the coil must have had a split causiing a leak between the two systems. When I took the old tank out it had loads of limescale, some of the bigger chunks were pipe shaped - as if they had formed on the coil and then dropped off. Some were quite thick.

I hope this information helps others with similar problems. Thanks again to all who posted replies.
Richard