Most people have a swimming pool to cool off in the hot summer. This is true, but you may find that most people who use this as a reason to have a pool, only use the pool a few times a year.

Many people swim for enjoyment, exercise, and for social occasions.

Having a pool that is not too cold, or too hot is a very attractive option.

Would you like to have a pool heating system that controls the temperature of the water, and keeps it at a comfortable level for the whole swimming season?.

If you do, consider your pool heating options.

 

Some basics:

 

Heat gain.

To heat the pool, we talk about heat gain. The heat gain is simply the amount of energy required to heat the pool to a desired temperature. The amount of energy required to heat the pool must take into account the heat losses. Heat losses for a swimming pool are huge.

 

Heat Losses.

Once we have the pool at desired temperature, how do we effectively keep the heat in the water.

The only answer is to use a pool blanket. Remember, the pool blanket is thin piece of plastic or closed cell mat. This is only a few millimetres thick. Most pools have little or no insulation through the walls of the pool. Compare this insulation to your hot water cylinder that is wrapped in thick glass fibre insulation, with silver reflective foil on the outside.

Your domestic hot water bill is one of the bigger utility bills, even though you are only heating a tank of around 150 litres of water.

Your pool may have many thousands of litres of water.

 

Heating Options:

 

Pool Blanket Only:

 A pool blanket is really designed to slow down the evaporation heat loss through the surface of the water. This is the main form of heat loss. This also means it slows down the water loss through evaporation.

If your pool is in direct sunlight, you will benefit from the radiated heat of the sun passing through the blanket and warming the pool. This is especially true in the warmer months of the year.

There are a few issues you need to be aware of with a pool blanket.

If we have some warm sunny days, and you lift the corner of the blanket, you will feel the water is nice and warm. Take a dive into the pool and you will be suddenly shocked at the cold water about 400mm below the surface of the water.

You need a way to try and mix this hot water on the surface with the cold water underneath.

If the weather becomes very hot, the pool water starts to get very hot.

It really is not fun when you come home from work on a stinking hot day and want to cool off in the pool, only to find the pool temperature is at 36 degrees.

You will need to constantly monitor the pool temperature and remove the blanket in hot weather, or replace the blanket when the weather is about to turn cold.

Forgetting to put the pool blanket on the pool before a cold windy night, will seriously shorten your swimming season.

The use of a pool blanket only, is fine, but it does not really extend your swimming season, it just makes the water a bit warmer in the warmer months.

If your pool is shaded in any way, the warming of the water will be very limited.

 

Solar Pool Heating:

 

Solar pool heating is dependent on the weather. If the sun doesn’t shine, the system does not work.

Fortunately, this is not a major problem with our abundant sunshine here in Australia.

A good quality, properly sized solar system can, on a 27 – 30 degree day, heat the swimming pool by 1 degree per hour. That is without the pool blanket, providing the pool is relatively sheltered from the wind.

The equivalent power output of a pool solar heating system on a warm day is off the scale when compared to any other form of artificial pool heating.

The coefficient of performance (input power vs output power) is huge, and can only be dreamed of using alternative options.

Not bad for old, and very basic technology.

 

The new technology is in the manufacture of the products. The quality of solar material these days is far superior to the older solar systems.

The best quality solar systems in the world are made right here in Australia.

Most customers who have a solar system, do not bother with a pool blanket.

The only running costs of the solar, are for the cost of the power to run the pump that circulates the water through the solar system. This should, in most instances, cost around $300.00 for the whole swimming season. The running costs would be zero if you had solar PV panels, as the solar pump only runs when the sun shines.

The solar controller will switch the pump off when the pool reaches desired temperature.

 

The cost to install a pool solar system is generally cheaper than any other form of heating. It will be cheaper to run, and if you install a good quality system, will generally last a lot longer.

It will also be cheaper to maintain than any other form of pool heating.

Solar pool heating, without a pool blanket, will give you around a 6 month swimming season – depending on the weather.

Some customers often install a pool blanket, in addition to the solar, to reduce the water evaporation, and save some money on pool chemicals. The blanket, of course, dramatically reduces the heat loss through the water surface.

This may add another 2 months to your swimming season, depending on the weather.

The solar puts the heat into the water, and the blanket keeps it in.

 

In the winter months, the solar will still add a few degrees to the pool temperature. For some this is enough, and they may use the pool all year round.

The temperature of the water very much depends on the weather. There is no guarantee of what the temperature of the pool will be in the winter.

For most backyard pools, this is fine. A heated swimming pool in the summer months that is cheap to run, cheap to maintain and will last for many years.

Most customers switch off the solar systems, or are set to a “winter” mode for the winter months.

 

Heat pumps:

 

Definition – A heat pump is not a pump.

A heat pump is a heat exchange system, based on an air conditioning system running in reverse cycle. The unit takes the heat from the surrounding air and transfers this heat to the heat exchanger. The heat exchanger coils are encased in a container with the pool water being pumped through. The heat in the coils is transferred into the pool water. Air to water heat pump.

This heat exchanger is generally made of titanium, to be able to withstand the corrosive nature of swimming pool water. A heat pump still requires a water pump to circulate the pool water through the heat pump.

The price of the heat pumps is generally determined by:

 

  • The size of the unit.
  • The quality of the titanium heat exchanger of the heat pump.
  • The inclusion of electronic expansion valves and associated electronic software. This provides the unit with a more flexible operating range, thus being more efficient, especially in cooler weather.
  • The inclusion of sophisticated de-icing systems to allow for operation in cold weather.

 

The real good news, is that the heat pumps available today, are far superior to the heat pumps sold only a few years ago.

 

As with any form of artificial pool heating, it is very important to have a pool blanket to limit the heat losses. This, coupled with the fact that a heat pump has a very slow heat up time, means that it becomes very uneconomic to not limit the heat losses from the pool water.

 

The advantage of using the heat pump, is that you have many options in the sizing of the unit to:

 

  • You can fit solar electric panels to provide free power to run your heat pump.
  • You can choose a unit that just takes the chill of the water in the summer months.
  • Or you can choose a unit that has superior cold weather performance to heat the pool all year round.
  • You can upsize the unit to heat the pool quicker so you can maximise the running cost saving using free solar power.
  • You can choose an inverter system that is super quiet to run, and can run on the cheaper “off peak” power.

 

A heat pump, or more accurately, your heat exchange system will obviously be very efficient in warmer weather, as there is more heat to exchange. In cooler weather, with less heat to exchange, performance of the heat pump will drop off sharply.

This is the reason why it is so important to choose the correct model and size for your pool, and to meet your expectations of the heating systems performance.

 

The following chart shows recommended pool heat pump sizing for your pool size and your desired swimming season. The estimated running costs are indicative only, and will depend on how you use the pool, and the cover.

The estimated running costs do not include any offsets by solar PV panels.

The electricity price is based on a price of 26 cents per KW/H.

12 Months Swim Season

 

Surface

Volume

Minimum HP size

 Annual

Pool cover on

 Annual

Pool Size

M2

Litres

no pool cover

Running Costs

18 hours per Day

Running Costs

7m x 3m

21

29,500

18 KW

$3,250

9 KW

$830

8m x 3m

24

33,500

 18 KW

$3,700

 9 KW

$950

8m x 3.5m

28

39,000

22 KW

$4,300

 9 KW

$1,100

8m x 4m

32

45,000

 22 KW

$4,960

 12 KW

$1,270

9m x 4m

36

50,000

 26 KW

$5,500

 14 KW

$1,400

9m x 5m

45

65,000

 47 KW

$7,100

 14 KW

$1,850

10m x 5m

50

70,000

47 KW

$7,700

18 KW

$1,970

12m x 5m

60

85,000

50 KW

$9,400

18 KW

$2,400

 

Summer Autumn Spring (9 Months)

 

Surface

Volume

Minimum HP size

 Annual

Pool cover on

 Annual

Pool Size

M2

Litres

no pool cover

Running Costs

18 hours per Day

Running Costs

7m x 3m

21

29,500

14 KW

$1,970

9 KW

$500

8m x 3m

24

33,500

 14 KW

$1,140

 9 KW

$570

8m x 3.5m

28

39,000

18 KW

$2,600

9 KW

$670

8m x 4m

32

45,000

 18 KW

$3,000

 9 KW

$760

9m x 4m

36

50,000

 22 KW

$3,350

 12 KW

$850

9m x 5m

45

65,000

 26 KW

$4,350

 12 KW

$1,100

10m x 5m

50

70,000

26 7KW

$4,680

14 KW

$1,200

12m x 5m

60

85,000

47 KW

$5,680

14 KW

$1,450

 

Summer Season (6 Months) Solar Replacement

 

Surface

Volume

Minimum HP size

 Annual

Pool cover on

 Annual

Pool Size

M2

Litres

no pool cover

Running Costs

18 hours per Day

Running Costs

7m x 3m

21

29,500

9 KW

$1,160

9 KW

$400

8m x 3m

24

33,500

 14 KW

$1,317

9 KW

$450

8m x 3.5m

28

39,000

14 KW

$1,533

9 KW

$530

8m x 4m

32

45,000

 18 KW

$1,769

9 KW

$600

9m x 4m

36

50,000

 18 KW

$1,965

12 KW

$680

9m x 5m

45

65,000

 22 KW

$2,555

 12 KW

$880

10m x 5m

50

70,000

22 KW

$2,751

14 KW

$950

12m x 5m

60

85,000

26 KW

$3,341

14 KW

$1,150

 

 See the  Astral Heat Pump Calculator

 

Pool Gas Heating

Swimming pool gas heating is the ultimate pool heater.  A gas heater can guarantee you a quick heat up time, any time and any weather.

As with any form of artificial pool heating, the use of a pool blanket is highly recommended if you would like the pool to heat up quickly, and you want to limit the running costs.

A correctly sized gas heater, operating in average conditions, should raise the water temperature by about 1 degree per hour, if you keep the pool blanket on.

There are no special circumstances for gas heating. You can manually turn the system on when you want the pool warm or set the system to come on automatically.

Swimming pool gas heaters come in all sizes and configurations to suit your pool. You can have free standing or wall mounted heaters.

The newer gas heaters are designed to be far more economical than older type heaters.

A typical swimming pool gas heating system will cost about $4,000 to $6,000 to install.

The gas plumbing is an additional cost and will depend on the size of the heater, the distance from the gas meter, the route the plumbing will take and the size of the gas meter.

The running cost will depend on how you use the heater.

 

Give us a call, we can help.