Question from Donald Bryars, via email:
I have a 12kW Aztec water heater for my central heating and domestic hot water. I have just fitted an unvented hot water cylinder and removed a header tank for central heating and a tank for the water supply. I now have a mains direct supply connected to an unvented cylinder. Do I still need a circulation pump for my central heating?
Answer from Russell Liversidge from TR Engineering:
Yes you do still need a pump to circulate the primary water around the system.