Except for perhaps three to four short months of hot weather in summer (if we’re lucky!), the UK is certainly far from being a place to enjoy a warm climate. Thus you’ll probably want to ensure your swimming pool has heating in order to enjoy it for longer periods of the year.
The following guide will explain how heat is lost from pools and how you can avoid this – amounting to a substantial saving in your energy bills. It will also outline your options for swimming pool heating, so you can make the best choice possible for your needs.
Swimming Pool Heat Loss and Prevention
In a nutshell, heat is lost from the floor, walls and of course the water surface of your swimming pool. This heat loss is at a maximum when the cover is removed and the pool is in use, mainly because of the effect of evaporation, which accounts for 70% of heat loss.
The rate of evaporation from the water surface of a pool is dependent on the initial pool temperature, surrounding air temperature and humidity, plus wind speed. This amounts to the fact that the higher a pool’s temperature and wind speed and the lower the humidity, the greater the evaporation. While counter measures such as planting trees, shrubs or a fence as a windbreak can reduce this evaporation, they will also shade the pool from the natural heating effect of the sun.
If you use your swimming pool for only 4 hours a day for 5 days a week on average and use a pool cover which acts as an effective evaporation barrier the rest of the time, this heat loss from the pool surface will only account for 12%. In fact, a solar cover can reduce evaporation water loss by up to 95%.
The rest of the heat loss will thus only occur from the floor and walls of the pool – this is a continuous dissipation into the surrounding soil and will depend on three main factors. These are the size of the pool (including depth), the heat conducting properties that the wall and floor is constructed with (i.e. if the water table is high and the swimming pool construction materials become saturated, this will result in a reduction of thermal efficiency), as well as the difference in temperature between the soil and the pool water.
The good news is that this type of heat loss can be reduced by over 90% using the right measures, such as if the external surface of the pool in contact with the soil is polystyrene. Because this material consists essentially of air bubbles encapsulated by a thin layer of hydrocarbons, it results in a ‘thermo flask’ seal which dramatically reduces heat extraction into the ground.
Another factor which will encourage heat loss is convection – if there is static water under the floor of the swimming pool then the water retains heat like an insulator. If the ground water is flowing however, then heat is lost at an alarming rate. Solutions such as permanent pumped drainage will increase water temperature significantly even for pools that don’t have artificial heating.
Main Types of Pool Heating Systems
Even if you have an existing swimming pool, you can easily add a heating system to extend your swimming season at home by an extra 2 – 3 months per year. These are your main options when looking into swimming pool heating:
Heat Pumps
Heat pumps that use the air as a heat sink will generally cost slightly less than a pound per day in power (depending on your pool size and required water temperature). As well as being soundly reliable, they normally last at least 5 – 7 years before needing to be replaced.
There are other types of heat pump available on the marketplace, but while these will be economical to run they will be much more costly to install.
Heat Exchangers and Direct Electric Heaters
These types of swimming pool heating systems are also reliable and cheap to maintain. They will only cost around 30% of the price of a heat pump, but the downside is they can use 10 times more electricity, which will bump up your fuel costs. Generally they will cost approximately ?12 per day to run.
Solar
While solar powered heating sounds like a great idea, the fact is that unless it’s a high-end system, it can be more bother than it’s worth in terms of maintenance and cost. What often happens is that after a few years of frost, even the best solar system will start to leak and require emptying. The best way to take advantage of the solar power of the sun is to insulate your pool floor and walls plus use an energy absorbing summer solar pool cover.
Conclusion
Since we here in the UK are not blessed with Mediterranean weather, Swimming Pool Heating is crucial if you want to have a dip more than a few times per year. It’s wise to take your time researching what’s available so you can not only find the best deal, but the right fit for your particular swimming pool.
John Williams is a retailer of Swimming Pool Heating products.