The principal cause of heat loss in swimming pools is through evaporation and if the temperature of the pool is to be maximized by installing a heater then steps must also be taken to reduce heat loss. This can be achieved by fitting an impermeable floating cover and owners who want to heat their pools are strongly recommended to fit one. There are various types of heater available details of which are given below:
Solar Panels
There are various types of solar heating designs, though all use the principle of pumping water through a collector, which absorbs heat from the sun. Some designs are enclosed in panels and there are exposed pipes connected to the manifold. Modern panels are made from flexible PVC and typically measure 3.0 m x 1.2 m. For effective heating the panel area required is between 60% and 70% of the surface area of the pool. The solar panels must be positioned so that they receive the maximum amount of heating during the hottest hours of the day. Careful consideration must also be given to the aesthetics of the installation. The system works on a by-pass system with three valves.
Electric Heaters
Electric heaters are designed to combine simple operation with high thermal efficiency. The heater consists of a series of immersion heaters arranged in banks of 9 kW, each bank being controlled so that heat output can be adjusted according to the requirement. The heater is installed after the filter and all the water returning to the pool is pumped through the heater. This in-line arrangement ensures that heat loss is minimized and all the heat energy is transferred to the water. The heater is installed complete with a control panel, which incorporates an electrical interlock so that the heater will not work unless the pump is switched on. The panel also has switches to isolate the mains power, a timer switch for automatic operation and switches for the individual banks of heater elements. Note that MCB protection is provided inside the panel on all circuits. If for any reason the pump or heater will not work, check that all the MCBs are "ON". If they are "ON" and the equipment will not work or if after resetting they immediately re-trip, a qualified electrician should be called to check the installation. As a result of their high power ratings, most electric pool heaters operate on three-phase power.
Heat Pumps
Heat pumps work by moving heat from one place to another; in this case from the air to the pool water. Imagine a refrigerator in reverse. Whereas a fridge expels air from an enclosed space to the surrounding atmosphere, a heat pump sucks heat from the ambient air and transfers it to the pool water. In general, a heat pump will transfer 5 or 6 units of heat for every unit of unit of energy consumed. Although the initial cost is more than other heating methods, the running costs are considerably lower solar panels excepted).
To heat the pool, the heat pump may initially have to left on for 24 – 48 hours but thereafter (as long as the pool is covered at night) it will keep the pool at the desired temperature operating for 2 – 3 hours daily.
Heat pumps are installed on a by-pass arrangement on the delivery line to the pool and so can be fitted retroactively.
Under Surround Heating
Under-surround heating works by diverting the water being returned from the filter through a series of pipes built into the pool surround. On a hot day the pool surround is warmer than the water in the pool and as the water flows through the pipes it absorbs heat. The warmer water is then returned to the pool via the inlets. The system is also operated on a by-pass system. For optimal heating effect, the under surround system should be operated during the hottest hour of the day (10.00 am to 4.00 pm). Effective heating will only be obtained when there is direct sunlight on the surround and the system will be ineffective when shaded either by cloud or trees. As this system only works when the surround is hotter than the pool water it will cool the pool if left on overnight.