Storage hot water heaters (also known as storage tanks, hot water tank, hot water cylinder) is a tank that is used for storing and heating hot water. The tanks are typically heavily insulated to minimise heat loss and energy consumption and can retain heat for days. Hot Water tanks may have built in gas burners, electric immersion elements, may use an external heat exchanger to heat water from another energy source prior to storing it in the tank or may even be coupled with a solar system.
Storage tanks typically work on mains water pressure. Mains water is connected to the base of the hot water tank via a series of connections and valves. The tank becomes pressurised once the tank and all associated pipework is full and up to the mains pressure.
Built in thermostats sense the temperature of the water in the tank then begins heating the water up to the selected temperature on the thermostat. Time taken to heat the stored water will vary depending on the fuel source (e.g. gas, electricity, solar…ETC), time of day and outside temperature. Once the water is heated to the desired temperature, inbuilt thermostats will automatically cut out and begin maintaining the temperature as required. Storage tank insulation retains a lot of the tanks heat, therefore minimises the amount of energy required to maintain temperature.
When hot water taps or fixtures demand hot water, the taps or valves are opened allowing hot water to flow. This is achieved by mains pressure cold water displacing the hot water being drawn from the tank, in turn forcing the hot water out of the open taps and valves. The cold water entering the tank mixes with the stored hot water and reduces the overall temperature of the tank. When the temperature drops below the thermostat setting, the thermostat will engage and activate the energy source to begin reheating the stored water to the thermostats temperature setting. Gas storage hot water heaters heat up the stored water throughout the day and night as necessary, however electric storage hot water heaters work slightly differently.