Central heating system. Header tank overflowing ?

Question

Thanks for your previous answers but I need to give more detail.
The header tank is overflowing, the water in the tank is warm, it is not entering the header tank via the ball valve and it is not entering the tank via the expansion pipe from the hot water cylinder down stairs (ie the pipe that is bent over in a 'U' shape about 2" from the surface of the water). Checked the thermostat it is ok and adjusted to 50c. The water is entering the header tank from a copper pipe that is in the bottom of the tank. When I shine a torch through the water to the bottom of the tank I can see a 'heat haze' effect (ie the hot water entering the tank) comming from this pipe at the bottom of the tank. ? It is obviously connected to the hot water tank downstairs by why is hot water syphioning up this pipe into the header tank ?

Answer 1

Are you saying that your header tank is filling to overflowing from the cold feed pipe at the bottom of the header tank? If so, it must be getting into the heating system frome somewhere that it shouldn't be!! What kind of boiler do you have, have you had something changed recently, how long has this been happening for??

Answer 2

This sounds like a similar problem to the one i had. When i worked on the central heating system last year the outlet wheel valve became seized in the shut position even though the wheel did turn in both directions. Thus there was no cold water feed to the boiler. When i tried the system, because the out let was seized shut the boiler very quickly over heated and vented excess pressure and water from the boiler to the header tank. Hope this helps.

Answer 3

The water is the central heating water as it flows around the system. If you have thermostatic valves then as they all shut down because the weather is mild then the water in the system starts to rise and comes back through what should be the top up pipe. Also check that the boiler stat is not now turned up too high as this, in mild weather could cause these conditions to happen.

Answer 4

call a plumber or electrician.
It may be that the thermostat in the immersion heater has broken in the "ON" position ( contacts welded together ) and the water will expand upwards into the tank as you have explained.
Urgent attention needed.

Answer 5

it sounds as if the system is "pumping over". this only happens at start up or shut down of controls. on the circulation pump you will see a three speed switch. try turning the speed down. this should cure problem.