Lesson 6
Combi, System or Regular?
Tell which kind of heating system you have from three clues, and see why height makes the pressure in an open-vented one.
Three homes, three systems
Ana’s flat has a combi boiler: one box on the kitchen wall with a pressure gauge on its front, no hot-water cylinder and nothing in the loft. It heats tap water the moment a tap opens.
Ben’s house has a system boiler: a boiler with a gauge, plus a hot-water cylinder in the airing cupboard, and an empty loft. Owen’s 1930s semi has a regular (heat-only) boiler: a cylinder in the airing cupboard and two tanks in the loft, a big one for cold water and a small feed-and-expansion tank for the heating. His heating is open-vented.
Three clues tell you which you have. A pressure gauge on the boiler means the heating is sealed. A cylinder means stored hot water. Tanks in the loft mean water fed by gravity. Systems do get altered over the years, so treat the clues as a strong start; the installation paperwork or a heating engineer can confirm.