What is causing the water in my heating header tank to boil so much?

This happened at my parents' house when they took out a couple of radiators - the system was then too small for the powerful boiler. In the end they didn't want to replace it with a smaller one, so they just had it on the lowest setting for very short periods. This works because they bought a new timer with multi setting capability and was cheaper than a new boiler.

Zoe
November 2006

your system is pumping over. which is where the boiler heats the water and rising up the vent pipe into the header tank. check your pump is working . check the speed of your pump. or most common you have a block in the pipe feeding the system from the header tank. it useally blocks where the pipe from header tank tees into the system pipe work corrosion clogs and blocks the pipe .if its that bad you can sometimes find the block by running a magnet down the pipe where it joins the system and see if it sticks. if it stick thats where the rust blockage is. or drain your system down and see if the header tank ballvalve starts to refill if it don't you no the water in not getting through the block. also see if the tank is got alot of silt in the bottom.

hi-spec plumbing
October 2006

just the same problem my son had with his if i remember it was his water pump stuck (there is a little plate you can take off the pump to check that) and also the thermostat that controls the heater was u/s

peter bainbridge
October 2006