Choosing A Pool Heater? What Are The Relative Performances Of Solar, Gas, Electric Pool Heaters?

Heating a pool can consume a great deal of energy and subsequently be very expensive. With pools consuming around one-third of a household’s electricity and heaters adding to this load, it’s worth being as efficient as possible. So how do popular swimming pool heating methods like solar, gas and electric compare?

Solar Pool Heating

Solar pool heaters typically consist of a set of roof-top solar tubes, a solar pump and solar controller.

Our experience with many installations is that average-sized solar heaters generally heat a pool by 2-3 degrees Celsius on a sunny day and extend your swimming season by a month or so at each end of the season. While large solar heaters can do more, the average solar heater is correctly sized when it has a surface area that’s the same size as the pool. Ideally, it faces north. Irrespective of size, all solar heaters suffer from the obvious effects of rain, cloud, air temperature and weather in general. They are good and reasonably economical boosters for your pool temperature but are not ‘reliable’ heaters due to inherently requiring sunshine to heat.

Most solar heaters are ‘open’ systems that pump pool water up to the roof, where it passes through black hoses or panels and then falls back to the pool. These typically require a large pump to push the water up. The heat may be free from the sun, but getting the water up to it, is not. Solar heaters must run during sunny times and, if you are using Time-of-Use electricity, running a solar heater pump can be quite expensive as the sunny periods correspond to shoulder and peak tariff periods.

Solar pool heaters can be independent or in-line.

Ideally, they are independent and they have their own suction points in the pool and (ideally) return via a pipe that is angled down and deep in the deep-end of the pool to mix the water. Independent solar heaters can operate on their own without the need to run the pool filter at the same time (when electricity is expensive).

In–line solar heaters take water to the solar pump, via the pool filter. This is usually expensive as the filter pump time-clocks need to be set to run from about 9 a.m. to about 3.30 p.m., depending on the orientation of the panels to the sun. The filter pump has to run at high speed during this whole time, in case the solar controller ‘decides’ to turn on. This means that the filter generally runs rain or shine – at times when electricity is expensive.

A Pooled Energy system controls both the filter and solar pumps so that the filter pump operates when electricity is inexpensive or at time when the solar pool heater is actually running – not during expensive periods. In addition, the filter pump is speed-controlled to run only at the speed required.

With Pool Energy’s internet connected weather-based software, your solar system will use considerably less costly energy and do a better job of heating your pool. You can control your solar system via the Pooled Energy smartphone app.

A pool blanket is a good supplement to solar heaters as it keeps water warmer for considerably longer.

Gas Pool Heating

Gas pool heaters are not subject to the intermittency of sunshine and are sized to heat an uncovered pool up by about 1°C per hour during the swimming season. .

Gas pool heaters are good for scheduled swimming. For example, if you swim on Thursdays at 10 a.m. every week, it is simple and relatively economical to heat your pool to the desired temperature using a sufficiently large gas heater (and pool blanket if needs be). If you want the pool to be warm/hot all the time, then a heat pump will generally be more economical.

The Pooled Energy system readily allows you to schedule such use and the smartphone app allows you to remotely turn the heater ON and OFF at any time. The Pooled Energy system will operate the gas heater with the correct water flows, adjusting the pump speed where required. It will also manage the necessary heat-up/cool-down sequences correctly.

Gas pool heaters are less energy efficient than Heat Pumps but will heat a swimming pool faster. Gas heaters are a good choice for spas that are heated only occasionally.

Make sure that you keep chemicals, inflammable materials, plastics and electronics at least one meter from the hot exhaust. Also make sure that you have heavy-duty PVC plumbing on the delivery side of the pool heater for at least two metres.

Pool Heat Pumps

Heat pumps which take heat from the air to heat your pool are more efficient and generally more economical than gas and not subject to the intermittency of sunshine. However, they heat about half as quickly; about 0.5°C an hour for a correctly sized system. In this case, you will probably need a pool blanket or insulating cover for at least the shoulder seasons and winter. Pool heat pumps and blankets are generally the better choice when you want the pool available to swim anytime.

The Pooled Energy system can manage the heater and the Pool App allows you to remotely turn the heater ON and OFF at any time. Water flow rates from the pool pump are also automatically adjusted to save on energy costs.

Pool heat pumps are most economically operated at night using off-peak electricity for those users who are on a Time Of Use tariff. Heat pumps have a COP (Coefficient of Performance) of 5-6, which means that they transfer five-to-six units of heat from the air to your pool, during normal operation. However, the COP drops as the temperature difference between the water and the air increases. Most heat pumps will become uneconomical to operate once the air temperature drops below 5-10 degrees (you need to check the data sheet for your particular model). If you plan to swim mid-winter, you should consider getting a heat pump with an extended air temperature range.

Electric Pool Heaters

Electric pool heaters used to be very common but are now very expensive to operate.

Most heat pumps use five-to-six times less electricity for the same heating. If you have a heater that uses an electric element, we suggest you calculate the operating cost before turning it on.

All Pool Heaters

It is almost always better to get a larger pool heater than you think you need. The reason is that it is faster and loses less heat during the heating stage, while requiring less water to be pumping. Overall, large pool heaters tend to require less energy than small ones and are more convenient.

Please contact Pooled Energy if you wish to add a pool heater to your Pooled Energy system and we will either supply it ourselves or recommend a suitable contractor.

Contact us at or 1300 364 703.


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