Central Heating Header Tank


Just woke up to a leak in the bathroom ceiling not what you want over the Holiday. The Header Tank in the loft for the Central Heating is the culprit and I have located the source. The problem I have appears to be with the Expansion pipe from the cylinder in the bathroom cupboard. When the Temperature of the water falls and it calls for the boiler to fire up the expansion pipe starts to empty water into the header tank. The water temperature is not excessive and by no means to hot. My system is the standard type with main tank in loft and header tank for heating. Why is the hot water rising in to the header tank from the hot water cylinder ? which is about five years old.
Any help appreciated no plumbers Polish or otherwise available over the Holiday. JD
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Well, something sounds although it is too hot. The expansion pipe is doing it's job. Are you sure the cylinder stat is not stuck or faulty?
ken
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fire
water
You seem to be implying that the expansion pipe from the hot water cylinder discharges into the boiler feed/expansion tank (the smaller of the two tanks). Is this correct?
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I have spoken to a plumber who advised to turn the pump down if possible and to try to elevate the expansion pipe higher. Evidently this is not unique to me. Will post when I have tried the advice. Thanks JD
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Looks to me as if your CH header tank was fitted by a cowboy. It should have an overflow.
| >> Just woke up to a leak in the bathroom ceiling not what you want over the | >> Holiday. | >> The Header Tank in the loft for the Central Heating is the culprit and I | >> have located the source. | >> The problem I have appears to be with the Expansion pipe from the | >> cylinder | >> in the bathroom cupboard. | >> When the Temperature of the water falls and it calls for the boiler to | > fire | >> up the expansion pipe starts to empty water into the header tank. The | > water | >> temperature is not excessive and by no means to hot. | >> My system is the standard type with main tank in loft and header tank for | >> heating. | >> Why is the hot water rising in to the header tank from the hot water | >> cylinder ? which is about five years old. | >> | >> Any help appreciated no plumbers Polish or otherwise available over the | >> Holiday. | >> JD | >> | >> | > | > You seem to be implying that the expansion pipe from the hot water | > cylinder | > discharges into the boiler feed/expansion tank (the smaller of the two | > tanks). | > Is this correct? | > | >Yes, | I have spoken to a plumber who advised to turn the pump down if possible and | to try to elevate the expansion pipe higher. | Evidently this is not unique to me. | Will post when I have tried the advice. | Thanks | JD | |
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I have followed advice and turned the pump down ,elevated the expansion pipe slightly and had some success in stopping the discharge into the header, as previously stated this appears to be not uncommon, maybe a plumber will respond with the technical reasons. Thanks for your replies JD
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Well, I'm not a plumber, but I had the same problem, it's called pumping over, and in my case it was caused by the vent pipe curling right over the edge of the tank. I cured it (on the advice of a plumber) by taking it about 18" above the tank before curling over. This increases the pressure on the column of water to make sure that it stays in the system, but still allows it to expand. It can also be caused by the pump setting being too high.
Steve
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for
and
I am still mystified at what you are saying, perhaps I did not make my previous question clear.
Do you mean that you have traced the route of the cylinder vent pipe and find that the open end goes into the small header tank and not into the larger cold water storage tank?
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There are two vent pipes one into the cold water tank and one into the central heating header tank. You could not vent hot water into the cold water system. Although I am sure a plumber would give you a better explaination. Somewhere on the web there must be a schematic drawing showing the layout. JD

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over
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I think I am catching up with you now JD.
The vent from the cylinder does indeed go to the cold water storage tank and expanded water would normally discharge into that tank and that tank only. If you trace the route of that pipe from the cylinder you will find this to be true.
The discharge you describe is coming up from the boiler vent. Pump over is not rare but is usually not noticed because the water is recirculated. I suspect that you have a faulty ball valve that is letting too much water into the system. Hold up the ball and empty out some water until the valve is clear of the water and see if it is still dripping. You should also sort out the overflow for this tank.
Hope this helps.
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Sorry, I misread your 1st post. You said header tank. You have a cold water cistern and a header tank. The header tank is for the heating or boiler to top up. The cold water cistern is to supply the hot water cylinder and for the vent pipe from the same.
ken
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water
After reading Ken's last post I wonder if I still understand the source of your problem.
Is the small tank or the large tank overflowing?
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Both tanks are fitted with overflows and function as and when required. (See Shazzbats reply) Thanks for the help and interest to all that replied JD
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It seems as if you've got a badly designed system. It all depends on where the supply or feed from the header tank is with respect to the vent pipe. If they are close together as they should be, you'll get very little pressure difference when the pump is running making the possibility of pumping over unlikely. If they are say fitted such as one is in the flow and the other's in the return then you'll get a higher pressure differential either meaning that it'll pump over with positive pressure, or suck air in with negative pressure. Either is bad for the system. If you suck air in, it's the oxygen that'll corrode the system. If you pump over, for a start you're wasting money by heating up a tank of water and depending on the water level and position of the overflow you can get a situation where water will discharge through the overflow pipe when the system is running and when it turns off the water level goes back down and then tops up through the cistern. Anyway, as others have said, turn down the pump speed and/or raise the vent pipe up. If neither of these work you'll have to modify the system. There is a device available for eliminating air, which you plumb the feed and expansion in together. Have a look at: http://www.screwfix.com/app/sfd/cat/pro.jsp?cId 0126&ts&569&id641

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