Central Heating header Tank - Overflow of water

janwalkowiak · 13 Dec 2005

Hi,
Help please,
Since I have had a water meter fitted the CH header tank continues to fill with water until it overfows. Water feels warm.
Fitted a new ball valve etc, seemed OK for a short time - a few weeks but now back.
Tried to turn down the water pressure at the meter but no change.
The ball valve seems dry on inspection so completely perplexed.
Seems to produce watr out of thin air.
One last thing of note the pipework seems a bit noisier than usual though this started before the water meter was fitted and no problems then.
Have to remove water manually from HT to prevent overflow, done this 3 time now.

Any advice very much appreciated.
(Fully pumped system with hot water tank).

JW

ChrisR · 13 Dec 2005

Water meter is coincidental - it doesn't affect the standing pressure, and neither can you by turning the stop cock.

Problem is almost certainly a leak between the tap water and CH water circuits, which will be in the HW cylinder coil. You'll need a new cylinder.
Presumably the level of the water in the big cistern is higher than that in the CH header one?

janwalkowiak · 13 Dec 2005

Chris,
Yes the other tank is fitted 3' above the header anyway.
If I put a food dye in the water tank will that prove it, or is there a more technical way?
Thanks it was one of the things that I suspected anyway but the water meter threw me off.

John

weareleeds · 13 Dec 2005

Before changing cylinder make sure system isn't pumping over (go into loft & get someone to turn c/htg only on then dhw only then both together for a couple of mins at a time while you check expansion pipe to see if pumping over is so may be blockage in "h"

janwalkowiak · 13 Dec 2005

Sorry Wearleeds - what do you mean by 'H' and how do I unblock if so.

I have seen the overflow running into tank when CH on thought this was OK!!

Thanks.

JW

weareleeds · 13 Dec 2005

The "h" is term used to describe the arrangement of how cold feed & expansion pipes are configured.You may not have one but there are thousands of homes that have. If you have what will be happening is the pipe from the boiler is pumped up & instead of crossing the "h" (as it is blocked) it goes up into the f&e tank from then the pump pulls water through the cold feed so in effect the tank acts as a radiator.To check try attaching a strong magnet to your copper pipes in airing cupboard on pump inlet & if it sticks you have a serious problem

bathjobby · 14 Dec 2005

What level do you keep the water in the F&E tank at ? The expansion pipe that has water coming out of it, what is the rate of flow approximately and how high above the normal level of the water in the F&E tank is the top bend in that pipe ? Have you changed the pump speed ?

bathjobby · 14 Dec 2005

What level do you keep the water in the F&E tank at ? The expansion pipe that has water coming out of it, what is the rate of flow approximately and how high above the normal level of the water in the F&E tank is the top bend in that pipe ? Have you changed the pump speed ?

janwalkowiak · 17 Dec 2005

Hi Everyone,
Bit more info over the last few days.
1. The water steadily flows/fast dribbles from the overflow. Not a drip but not a full flow by any means.
2. I can finally say it only does it when the heating is on. Does not happen when on hot water only.
3. I try to keep the level where the ballcock is just off, probably a few inches from the bottom of the tank.
4. The top bend of the overflow is about 12-14" above the CH expansion tank water level and about 24" below the bottom of the raised cold water tank.
5. No changes to the pump pressure made by me unless a fault.
6. Unless the excess watercomes through the cylinder coil as suggested by someone earlier where does it come from? It is very clean and I must have removed 6-8 gallons of it so far.

When the water meter was changed we were clearing out the loft in this area could something have been altered then.

Lastly would turning down the pump pressure have any effect?
Any help much appreciated.

Happy Christmas and New Year to All.

John W

JohnD · 17 Dec 2005

Are you sure the water is not being fed through the ballcock? When you said it started after having a water meter fitted I wondered about debris from the old pipes lodging in the valve.

You might be able to test this by putting a large jar under the feed and seeing if it fills up and overflows.

If i understand you correctly there is no sign that water is coming from the vent pipe which curves over the top of the tank.

Also - is there any gas in the radiators? When you get gas it displaces the water into the expansion tank.

chrishutt · 17 Dec 2005

JohnD said:
is there any gas in the radiators? When you get gas it displaces the water into the expansion tank.

What? I think your feverish imagination is getting the better of you.

Stoday · 18 Dec 2005

chrishutt said:
What? I think your feverish imagination is getting the better of you.

He means hydrogen gas, not mains gas.

If fresh water is being drawn into the heating system, it will bring dissolved oxygen with it. The oxygen corrodes the steel radiators producing iron oxide and hydrogen gas.

http://www.plumbingpages.com/featurepages/WaterProblem.cfm

JohnD · 18 Dec 2005

chrishutt said:
What? I think your feverish imagination is getting the better of you.

my imagination thinks up much better ideas than that

janwalkowiak · 6 Apr 2006

Hi all those who replied, and thanks.

In the end it proved to be the heating coil in the hot water cylinder.

Went downhill quite rapidly in the end and so replaced cylinder - and now all OK. Price of Copper must be a bit steep at moment.

Anway thanks again - no more removing water, no pumping over, and system overall much quieter.

JW

Nige F · 6 Apr 2006

janwalkowiak said:
Hi all those who replied, and thanks.

. Price of Copper must be a bit steep at moment.

JW

What, You mean you got more than £5.00 @ the scrapper for the old one

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Central Heating header Tank - Overflow of water

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