Continually running header tank but not overflowing

[chrisneill]

Really hoping you can help.

I have just had my CH header tank replaced (in the loft) as it was very corroded and running continuously. I assumed that the ball cock was faulty and the continual flow was going out the overflow pipe. Header tank and new ball cock later and the continual filling of the h/tank continued, but not overflowing (therefore stays at the same level). When I say the water is continually flowing, it is but not with any pressure - so effectively, a continual top up (but not by water dripping in - it is flowing in). The water of course must be going somewhere, and last night, I ruled out evaporation, as this continues 24 hours a day, regardless of whether the heating is on.

I am assuming that I may have a leak under the ground floor. Everywhere else checks out ok.

I have a suspended floor throughout the downstairs.

I have no idea how long this has been going on for. I assume I could be causing considerable damage over time, if i do not sort it soon? Because of the amount the header tank is refilling, I imagine a stop leak additive will not work and the best suggestion is to start pulling up carpet and floorboards. Any suggestion in simpleton's language would be very much appreciated.

Chris

 

[dcawkwell]

Yes you have a leak.

I would suggest have a plumber come
who has compressed air empty the system and fill the system with compressed air running in from a compressor by listening
carefully with the air running in at pressure you will be able
to hear the leak. Perhaps ask them how they would
go about finding the leak if you don't get a satisfactory answer move
on to someone else.

There are commercial companies that will do this and place
microphones on radiators pipes as well as thermal imaging cameras
to pinpoint the leak. Expensive but will find it.
I am currently on a house damaged by freezing in Dec 2010 currently
on the 3rd leak and haven't even got to the central heating I expect more.

Alternative is isolating separate parts of the system until the leak stops.

Good luck.

 

[chrisneill]

Thanks very much for that. I have only been in the house for 4 months. This for all I know, could have been going on for years!! Bearing in mind the rate of flow and the fact it is potentially leaking 24 hours a day, could the damage be significant?

 

[JohnD]

do you have a hot-water cylinder? and a large cold-water tank in the loft, to feed the bathtaps?

 

[chrisneill]

Hi - yes to both questions.

 

[dcawkwell]

Thanks very much for that. I have only been in the house for 4 months. This for all I know, could have been going on for years!! Bearing in mind the rate of flow and the fact it is potentially leaking 24 hours a day, could the damage be significant?

Fresh water entering the system will greatly increase the speed of rusting
in the system.

 

[chrisneill]

Thanks. I was primarily concerned what damge the leaked water could be doing to he foundations or structue of the house. Much to worry about?

 

[JohnD]

turn off the water-main stopcock for a while, and use no water. You already know the water level in the F&E tank will drop, see how much after half an hour. Now look at the big tank. Has that dropped at all?

 

[StephenW]

I would:-
1. Check that no water was coming from the hot cylinder expansion pipe into whichever cold water tank in the loft (this would probably indicate a hole in the coil inside the HW cylinder) and could depend on the relative heights of the two loft tanks.
2. Assuming you have floorboards downstairs, remove a board near to a radiator and use a torch and small mirror to scan under the floor looking for signs of water. Repeat for other radiators.
If nothing is obvious then call the experts.

 

[chrisneill]

will do. Cannot do this until tomorrow night. What might this tell me and should I leave the ch running whilst I do this? I'm assuming not.

 

[JohnD]

you can leave the CH running until/unless the water in the F&E drops to the level of the outlet pipe in the bottom. If you are up there watching it, you can keep an eye on it.

although it would be less worrying to turn the pump off, there is a chance that the running pump is related to the loss of water.

Is it a condensing boiler, and do you know where the condensate pipe runs?

 

[chrisneill]

JohnD, now we reach the limits of my knowledge. What do you mean re condensing boiler? The flow into the ch header tank is from the mains and the flow out is from beneath, feeding the radiators. does that help? I am convinced it is a leak but asking around at work, they do not seem to be as confident as i am - hope they are right!

 

[popeye2755]

I presume you have access to the sub-floor? Take a torch and crawl around under the ground floor. If the leak is as big as it sounds, it should be easy to spot.

 

[JohnD]

I have a feeling it is not a condensing boiler - these are the more modern and efficient ones that tend to make a lot of steam from the flue on a frosty day.

make and model will help.

 

[HERTS P&D]

I suspect a leak on the ground floor, turn heating on and see what radiator needs bleeding, this might give you a clue where the leak could be.

Andy