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Brrrr… that’s cold.

If you’re familiar with this, just want to get an early start on pool season, or simply prefer warm pool water, you should look into heating your pool.

Often, concerns about running costs come up with this topic. For this reason, we will focus here on more affordable options that keep running costs and the time and effort required to set up and operate the system within reasonable limits.

In this article we present a number of proven methods. Some of the methods presented can be implemented for any swimming pool, while others are not universally applicable.

Method #1: Solar pool heater

Essentially, there is no cost to operate a solar heater. The only cost incurred is the minimally higher operating cost of the pool pump to additionally pump the pool water through the solar panels.

Solar heaters have their own solar panels that capture heat energy from the sun and transfer it to the pool water. For solar heaters, we have coined the 80% rule. The rule states that the total area of the solar collectors should cover 80% of the pool area. For pools used year-round, you should have an equal or even larger area of solar collectors.

The disadvantages of solar heaters are that, on the one hand, you need the space for the solar collectors and depend on the sun always shining

On the other hand, solar pool heaters are a very economical solution due to their low manufacturing costs and quasi-free operation.

SunHeater S120U Universal Solar
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What’s exciting about solar pool heaters is that you can also use them to cool a pool. To do this, simply run the pool water through the system at night or when outside temperatures are low.

Method #2: Heat Pump

The best types of heat pumps are the so-called air source heat pumps. These units are quick to install, as you simply place them on the ground and connect them to the pool using only an inlet nozzle.

Air-source heat pumps draw in outside air, heat it, and then pass it on to the pool. This type of pool heating is environmentally friendly because it does not use fuels such as oil, wood or coal. How environmentally friendly it is to use, however, depends on the exact mix of electricity.

A heat pump is quite expensive to purchase, but provides warm pool water all year round.

Hayward W3HP21404T HeatPro 140,000
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Tip: A heat pump draws heat from the air. Consequently, the heaters should be operated when the air temperature is at its highest. So set your filtration system and pool heater to run during warm times of the day. This way, you optimize efficiency and can reduce electricity costs.

Method #3: Pool covers

Swimming pools lose heat primarily through evaporation. More than 75% of heat loss is due to evaporation. For this reason, significant savings can be achieved by keeping pool water evaporation to a minimum. Controlling evaporation is therefore a key to reducing heating costs, and the most efficient method is to use a pool cover.

The pool is completely enclosed by the cover, so the water cannot escape. Along the way, you also reduce your need for chemicals because they are also lost through evaporation. Essentially, there are two different types of pool covers: Automatic pool covers and pool cover tarps.

Automatic pool covers are permanently installed devices that can often be retracted and extended by timer or remote control. In this process, slats are slid along tracks onto the pool, much like a louver.

More expensive models often involve a single panel that is moved by a motor and can usually be walked on. In this way, a swimming pool can be wonderfully integrated even into smaller gardens, because the electric motors are powerful enough to move even whole sets of furniture with couches or, for example, a beach chair including hammocks.

Besides the fact that evaporation is close to zero, the automatic covers also protect against insects, wild animals and are the best safety measure to prevent small children from accidentally falling into the pool.

A much less expensive alternative to automatic solutions are pool cover tarps. The tarps are usually made of vinyl sheeting and likewise avoids evaporation and in this way helps to reduce heat loss and keep the pool warmer for longer. However, the safety risk of small children falling into the pool still exists here.

Blue Wave Bronze 8-Year 24-ft Round
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Method #4: Solar hose

A solar hose is the cheapest way to heat the water in your pool. The principle here is simple: the pool water is passed through a black garden hose, which naturally heats up due to its color.

This method lends itself both as a temporary solution for pools that are only set up in the summer, or as a permanent installation. Similar to a solar pool heater, such a solar hose can be placed on the roof of a shed or on the roof of a house. It is best to place the hose rolled up in the shape of a coil in your garden or on a roof.

A solar hose is, of course, less efficient than the other methods when it comes to heating pool water. On the other hand, a solar hose is free to operate and it’s easy to simply replace your existing garden hoses with solar hoses.

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Method #5: Solar rings

Solar rings are an alternative to pool covers. Solar rings are placed on the surface of the pool to collect solar heat and use it to warm the pool. They are circular rings that have air enclosed in them. The sun heats the air cushions and they transfer the heat to the pool water.

Get enough solar rings to cover most of the water surface. Some models have ways to connect multiple rings together. A common solution for this is small magnets attached to the sides.

In general, solar covers are a better choice when compared directly to solar rings. Heat utilization is better, and in terms of purchase, a single pool cover is cheaper than a number of solar rings.

In return, the solar rings have the convenience of getting a few and simply reordering more as needed, while the pool cover liner should fit the exact dimensions of the pool and may need to be cut to fit.

Pool heating costs: what are the operating costs?

A warm pool is a great thing to have. Especially for children, who in our experience are usually a bit more sensitive than adults to cold pool water, the methods presented for heating the pool water are a great thing.

Unfortunately, many pool owners underestimate the ongoing cost of a pool heater. Running costs are not to be neglected when deciding whether or not to use a particular type of pool heater, as you will likely want to use your pool for many years to come and heat it for a long time.

For this reason, we have compiled below how the operating costs are composed:

  1. Initial heating: shortly after the pool is put into service to start the pool season or after the pool water has been replaced, the pool water must first be brought back to operating temperature. Initial heating of the pool water takes time and consumes a lot of energy.
  2. Continuous operation: In the absolute height of summer with many hours of sunshine per day, the pool water heats up by itself. Outside the really hot months and on cloudy days, the pool water cools down steadily. In an outdoor pool, the water cools by 1° Celsius to 2.5° Celsius every day. The exact temperature loss depends on the air temperature, the current water temperature and many other factors. The pool heater must work against the constant heat loss. And that produces costs.
  3. Care & Maintenance: In addition to electricity and energy costs, any type of heater needs regular care and maintenance. This also costs money and is reflected in the operating costs.

Total costs of different types of heating

The cost to purchase and operate varies for different types of pool heaters:

  • Cost of a Solar Absorber Pool Heater: A solar pool heater is very inexpensive to purchase and operate. With a little craftsmanship, a solar heater can be built with some materials from the hardware store itself. The only operating costs are the electricity costs for the circulation pump.
    With a single solar heater, however, it is usually not done. Either many solar elements must be combined with each other or other methods must be used to heat the pool water.
    Prices for high quality solar heaters start in the low triple digits. Operating costs result from the additional load on the circulator. Exact running costs are difficult to determine, but are in the range of a few Euros per month for most pools.
  • Costs of a heat exchanger: A heat exchanger uses an already existing gas or oil heating system. The pool water is heated with this energy. Most heat exchanger systems operate at a temperature of 80°C and can therefore heat the pool water effectively. However, the additional energy consumption is of course reflected in the cost of operating the heating system.
    The purchase cost of a heat exchanger is about 1.000 to 1.500€. The operating costs are lower than for electric pool heaters, but higher than those for operating a heat pump.
    Depending on the price of oil and gas and how they develop over the years, the running costs of a heat exchanger can rise or fall. For heating a small pool during the summer months, however, heating costs of € 1,200 should be planned. For a large pool, the cost will be double or more.
  • Cost of an electric pool heater: If you want to swim in your pool in all weathers and you can’t fall back on an existing heating system, you can opt for an electric pool heater. These are very easy to integrate into any pool system. In terms of operation, electric heaters for pools resemble normal instantaneous water heaters from the bathroom.
    The water passes through a heating coil and is heated as it flows through. The power consumption is correspondingly high. The electric heaters are the example that not only the initial cost should be considered. In fact, compared to the initial cost, the electric pool heaters are the cheapest.
    Especially the cheap electric heaters usually work less energy efficient and therefore cost you a lot of money over the long time. The advantage of pool electric heaters is that the operating costs are not dependent on the weather or prices for oil or gas.
    The initial cost of such a system is usually only 500 to 800€, but the running costs of an electric heater for small pools quickly exceed 2,500€ per pool season. For large pools, the running costs can also be two to three times as high.
  • Costs of a heat pump: Heat pumps extract heat from the ambient air and supply it to the pool water. The use of such an air-water heat pump makes sense especially for owners of garden pools. In the case of heat pumps, the cost depends primarily on the power of the heat pump. The required power is primarily determined by the size of the pool, the desired water temperature and the time of use. The greatest heat loss in (outdoor) swimming pools occurs through evaporation.
    An important parameter for heat pumps is the so-called “coefficient of performance”. The coefficient of performance indicates the ratio between the energy supplied and the energy delivered. For example, with a coefficient of performance of 4.5, one kilowatt hour of supplied electricity is converted into 4.5 kilowatt hours of thermal energy.
    However, the coefficient of performance is not fixed for individual units, but also depends on the air and water temperature. However, high-quality heat pumps usually achieve a higher coefficient of performance than very inexpensive models under the same conditions.
    For the operation of a small pool, operating costs of about 500€ must be planned. The initial cost of a heat pump is about 3,500€. The operating costs increase almost equally with the size of the pool, while the purchase costs differ comparatively little between different powerful heat pumps.

Tips & tricks for heating the pool

  • High water temperature means high energy demand: the warmer you want the pool water to be, the more complex and expensive it will be to reach and maintain this water temperature. Sure, everyone has their own thermostat and finds a unique temperature comfortable. Who doesn’t know when one person feels comfortable at one room temperature while others are still freezing. However, the desired pool temperature also has a big impact on the energy required. When heating the pool water, an additional degree Celsius of water temperature corresponds to about 25 to 35% more energy. So warm water is nice, but it also costs more.
  • Pool environment has an impact: Wind affects the heating of the pool. Heat loss through evaporation depends on the air temperature, humidity, and surface area of the pool. If the pool is flat and calm, the surface area of the water will match the dimensions of the pool. However, if wind causes waves, the surface area of the water increases and more evaporation occurs. So create a wind-protected environment to avoid heating the pool unnecessarily.
  • One solution is good, but more is better: all the methods presented work, but you will have the best result if you combine several approaches. For example, use a solar pool heater to heat the pool and use a pool cover whenever the swimming pool is not in use.
  • Algae like warmth: Warm water also provides good conditions for algae. Therefore, use preventive algaecides to avoid algae growth.
  • Pool size matters: The water of a small children’s wading pool can be heated more easily and quickly than is the case with a larger pool. Depending on the dimensions of the pool, you will need to size the methods used accordingly. So a simple solar hose is not enough for a 15 m³ pool, but can be just right for a wading pool.
  • Heat the pool with or without a tarp: A pool tarp reduces heat loss through evaporation. Therefore, even when heating the swimming pool, such a cover should be used to speed up the process.

Warm water is a fine thing. With the methods presented and our tips, you can achieve just that and save your wallet in the process.

More questions

How much does it cost to heat your pool?

Pool heating costs can vary widely. Depending on the method and type of pool heater, costs can range from a few dollars to thousands of dollars per month.

Is a pool heater worth it?

If you have the budget needed, purchasing a pool heater is worthwhile. However, you can get efficient pool solar heaters or pool solar tarps for a small price.

Can you heat the pool using solar energy?

To use solar energy as efficiently as possible, there are special solar heaters for the pool. Solar tarps, which only need to be placed on the water surface, can also help with pool heating.

When should you heat the pool?

Heating during spring and fall is especially worthwhile. This can extend the pool season by several weeks, if not months.

Can paddling pools also be heated?

Even smaller paddling pools can be heated. However, this is not as effectively possible as with garden pools, which have appropriate connections.

Larry has been a true water rat since childhood. Pure pleasure turned into a passion. That's why he is the first point of contact for friends and acquaintances when it comes to pool-related problems. He is an integral part of the PoolHandbook editorial team.