This system is primarily designed to deliver hot water to the area of use. In the non-vented category, the system consists of a cold water reservoir, usually a tank, open vent pipework, heat source and a hot water storage tank. The primary feature is that the hot water reservoir is not vented: the reservoir acts as a form of a pressure vessel, and the cold water replaces any evacuated hot water. The vented system, on the other hand, includes a copper reservoir with an integrated valve for pressure release into the atmosphere.
Utilises either gas, oil or electricity to heat water in an insulated reservoir. This type is designed to keep the water at a set temperature, with heating cycles to maintain that temperature. A set of pipes then connects the tank to the points of use. A crucial inclusion is a temperature and pressure relief valve for safety. It serves to release the pressure from the accumulated steam once a pre-set limit is reached.
The tank is typically made of steel with a special lining to prevent corrosion, as well as an anode rod made from magnesium. Over time, the rod depletes, since it corrodes in place of the tank and thus has to be replaced. Other vital components include the drain cock under the tank and a hot water valve in case the hot water is not required for some time. Older versions of the system consist of the oil-fuelled heaters, which directly heats the tank at the bottom to heat the water through conduction. High risks and heating inefficiency has however seen this type being replaced by the electric heaters.
One of the key factors that determine the tank size is the recovery rate. This refers to the rate at which the unit heats water—low recovery rate heaters require bigger tanks to ensure anadequate supply of hot water. Electric heaters have a lower recovery rates and are thus used on the large tanks, especially for family use. Oil-fuelled heaters pose a higher recovery rate, so large tanks are not necessary.
This type lacks the tank: the water is heated on demand at the point of use, for example, on your Rain shower head. There are two types of the tank-less heater. The first integrates a small heater at the point of use, for example, just near the high pressure shower head. The incoming supply thus has cold water with an allocated setting for temperature control at the endpoint.
The second type has a coil, with one end in the cold water supply, and the other connecting to the hot water system that heats the house. As the water that heats the house moves around the house, it heats this coil, which in turn heats the cold water. However, some of the disadvantages include temperature control, especially for instant showers. There is a high chance of scalding since water is heated at the point of use. Secondly, especially when the source of heat is near the point of use, the rate of heating may be low in high demand times.
The choice between the two depends on the hot water demand, house design and your preferences. Most of the traditional houses features the tank systems. However, the leaning towards energy efficiency has had many people switch to the instantaneous heaters.