Header Tanks

A header tank is a large cold water tank usually stored in the loft or attic; it has to be in a higher location than the cylinder which is normally stored in the airing cupboard. The storage cylinder is fed at the base by pipe work coming from the header tank. The water pressure and flow of this type of system is driven by gravity i.e. the weight of the water in the header tank has sufficient weight to pressure the water down the pipe that feeds the water storage cylinder tank and back up to any tap or shower outlet, providing it is lower than the stored water level. When the water heats it rises to the top of the cylinder tank where it is drawn off through the hot water supply, this water is then replaced in the cylinder by the header tank. Heating causes the water within the cylinder to expand, a vent pipe allows a safe route for this excess pressure, air bubbles and steam should the system overheat, this then runs back up to the header tank where its open vent is located just above the water level.