pumping over prob?

[syncmaster]

i have lived in the house for 20+ yrs never had prob before.

the heating system is a back boiler with the cylinder cupboard up stairs in airing cupboard there is no pump or motorised valve in the cylinder cupboard. the cold water storage tank is also in the airing cupboard with the header tank in the loft.

was heating the hot water up via the controls from the back boiler( not immerson) and the header tank in the loft after bout 45 min started to pump over via the vent. any help? many thanks

 

[Agile]

There are lots of postings about pumping over on this site including a current one. Also see the FAQ !

Its most likely to be as a result of a blockage in the system.

Is the water like black treacle?

Tony

 

[syncmaster]

it was brown

 

[namsag]

By pumping over after 45 mins do you mean water shoots out of open vent every once in a while as opposed to a steady stream if so it is probably your boiler stat that has gone if accompanied by thumping and rumbling sound