Solar water Heating

Solar Water Heating Explained

The knowledge of using the Sun's rays to heat water has been known for thousands of years and is easy to understand. A hosepipe lying on a lawn will absorb solar energy and heat any water inside it. This is the basic principle of all modern solar collectors, the major difference being their ability to concentrate the energy reaching the liquid and their ability to massively reduce heat loss.

Types of Collector

There are basically 3 different types of collectors to cater for individual needs and situations

1. Vacuum 'Tank & Tube' Integrated Units

An economic introduction to the highest efficiency solar collectors with no external energy requirement The thermosiphon system is an array consisting of 15 to 20 vacuum tubes and a store of hot water above. The array is secured on a stainless steel frame supporting an insulated cylinder of up to 150 litres and is ideal for both flat and pitched roof installation.

This system works on the thermosiphon principle that when the water is heated by the sun inside the evacuated tube, it rises, being replaced by cooler, {more dense} water under the influence of gravity. Therefore no electricity is needed:- all that is required is a water source that is able to fill the tank, making it the most suitable for low impact dwellings. This water source may be from a tank or mains supply and the desired flow can be achieved either by a natural head, i.e. gravity fed from above, or by the use of a pressure pump, 12v DC or 220v AC.

Key Benefits

solar heating unit2. Pressurised Tanks

The SPP is a an advanced design which offers the user greater flexibility with regards to unit situation and offers the benefit off mains pressure hot water which is of the same quality as that which is supplied. If mains water is inputted to the system, hot water will be supplied at the taps enabling its use for cooking, pre-heating kettles etc. further reducing energy consumption.

Also, the fixed thermal store of water eliminates problems of lime scale buildup, therefore prolonging the life of the system without the need for water treatment, itself inexpensive, but requiring the annual inspection and maintenance of the unit.

The inner tank is fabricated using imported SUS304 1.2mm stainless steel, which when used with argon arc welding technology, significantly decreases the possible corrosion and all joints are tested to 0.8Mpa pressure. Heat tubes conduct the heat energy in a single direction which has the advantage of quick operation, high heat efficiency and anti-corrosion.

This system has many advantages over conventional water tubes. Since no water is used, there is no need for the use of anti-freeze, there is no possibility of internal corrosion and / or system contamination, no water and an almost unlimited care-free operation
Obviously energy (and cost) will be conserved if the pipe runs are kept to a minimum, but also standing losses can be reduced if the integrated tank can be situated in an area of reduced exposure (wind, driving rain)

Key Benefits

3. Heat Pipe Panel Manifold

The most advanced solar collectors with tubes being installed in 20 or 30 tube arrays and the storage cylinder being separate allowing greater flexibility and use of system - UNDERFLOOR and SWIMMING POOL heating. These systems are the most advanced solar system on the market.

The heat pipe tubes as, detailed above are inserted into a small diameter header manifold which contains a reduced quantity of water (1.5 litres). This allows very efficient collection of even the smallest amount of energy which can then be stored in a well insulated tank removed from the elements and providing an airing cupboard inside. The panels can then be situated anywhere and cause the least visual impact (particularly on pitched roof installations).

Also the ease of interconnectivity means that 2 or more panels connected in series can cater for larger households or further applications including under floor heating systems, swimming pool and hot tub heating.

Solar heat pipe

The heat pipe (copper insert inside the vacuum tubes) is in itself a hollow tube, with a partial vacuum inside. In this instance the vacuum is not for insulation purposes, but to reduce the boiling temperature of the fluid inside (water and a non toxic additive). The fluid boils at approximately 30°C and the vapor rapidly rises to the bulb at the very top of the tube. It then condenses as it is cooled by the water in the tank releasing the heat energy (latent heat of evaporation) and returns to the bottom to once again repeat the process.

Key Benefits