Hot Water Storage Tanks

All hot water storage tanks must be well insulated to keep the water hot during the night. Heat loss depends on many factors (ambient temperature, wind, season, etc.) and will be approximately 0.5 to 1 Centigrade per hour during the night. Experience shows that a minimum thickness of insulation of 100 mm should be maintained.

There are several different sizes of tanks available. All tanks must have connections for cold water inlet and hot water outlet as well as two connections for circulation pipes. These hot water storage tanks can easily be fitted to a stand. An electric element can be inserted, even after the installation, as there is a flange for this purpose. The flange at the bottom serves also for cleaning and maintenance of the tank.

These hot water storage tanks are made for low pressure use only. They can withstand a pressure of approx. 30 meters head. It is important to select correct connections to guarantee trouble-free functioning (as shown in the drawings).

Shape -two important factors influence the shape of a tank: -The smaller the diameter the less the tension (because of pressure from the inside) -The larger the outer surface of the tank proportion to its volume, the greater the heat losses.

Types -there are vertical and horizontal types available. For solar hot water systems with thermo-siphon circulation the vertical position is essential for proper circulation and hot water availability.

Hot water availability: A vertical hot water storage tank will provide more liters of hot water (having a

smaller volume of mixed water)

Cold inlet and hot outlet - these pipes must be welded to the hot water storage tanks by the anufacturer so that the incoming cold water will not mix with the hot water inside the storage tank (by fitting a baffle plate or by a tee on to the cold inlet). It is important to follow the rules for stallation of the hot water storage tank (as shown in the tables) so as to guarantee satisfactory hot water supply.

Sizes of hot water storage tanks -must be of adequate size to fulfill maximum requirement of hot water per day, or per heating time cycle.

Because of the intermittent availability of solar energy a large insulated storage tank is required, with a lagging of 100 mm. It is poor planning to install and undersized tank, no matter what heating medium is used: Sun, gas, oil, electricity. A well insulated storage tank keeps the water hot during the night. The storage tank and the circulation pipes must have a weatherproof cover when exposed to outside climate.

If an all-solar system is to be installed, then a tank with a capacity of between two and two-and-a-half times the daily consumption is suggested, owing to the intermittent nature of the solar energy received.

To estimate the daily usage, a figure of approximately 25 to 40 liters of hot water per person may be used.

Once the decision has been made on the type of energy-system, i. e. all-solar or solar with auxiliary boosting circulation of flat tank collector, then the tank capacity and collector area must be decided. These are determined by the daily requirement of hot water. Count approximately 50 liters of hot water per day for one collector surface of 1.m².

Quality and maintenance - corrosion of pipes and tanks is greater with hot water. The water should not be heated above 60 to 65 Centigrade. PE or PVC plastic pipes are easily damaged by hot water, and their use should be avoided. Heat, causes pipes to expand, thus increasing the length of the pipeline. It is therefore necessary to take proper precautions to allow for constant expansion and contraction due to changes in temperature.

Nowadays solar water heater systems are often made of galvanized M. S. Sheet metal, and are therefore protected from rusting. If the galvanized layer is damaged, or after several years of service, they may have to be painted with a good paint. The collectors and the hot water storage tanks require cleaning and painting before rust takes hold and causes damage.

For more info contact Ariston Solar Water Heater or call us at +971 4 252 2966