Solar Pool Heater – A Viable Option?

A solar pool heater uses energy from the sun to heat your pool – which of course is free and environmentally friendly.

It has other advantages too:

Can be installed by pool owner – Solar heating kits are available that suit both above ground pools and in ground pools and are easy to install. There is no need for qualified gas contractors or electricians. The main issue is the installation of the solar collectors which can be on a roof or on a frame angled towards the sun.

Little maintenance – Once installed the system requires little maintenance which compares favorably to gas and electric heaters.

Long lasting – A solar pool heater will last a long time and hence maximize the return on your investment. 15 year guarantees are available.

Solar Heater Diagram

Solar Heater Diagram

However there are a number of disadvantages to consider:

Needs large area for solar collectors – As a rough guide the area of the solar collectors will be need to be 50-100% of the surface area of the pool. Even with a small pool this can be a significant space requirement and may spoil the appearance of the pool surroundings.

Not as powerful as gas heater or heat pump – Even in ideal conditions the heat output from a solar pool heater will not match those of gas pool heaters and electric heat pumps. Solar heaters are not able to raise the water temperature as much as gas or electric heaters and may take several days to achieve the sort of temperature raise other types of heater could achieve in a few hours (so a pool cover is essential).  Solar heating will still work on overcast days but the output will not be as high as on a sunny day.

Dependent on Local Conditions – The effectiveness of a solar pool heating system will depend on average temperature for the location, wind factors, the angle and orientation of the collectors and the solar exposure. To work at their best the solar collectors need to be facing south and not be shaded by trees or anything else at any time of day.

Can be expensive – The cost of buying a solar pool heater system depends on the area of solar collectors you need. For an in ground pool it can work out more than the cost of a gas heater.

What is available? -If you have an above ground pool you can buy small space saving devices and ground standing solar panels which you position in a sunny spot and pump the pool water through them. In the right location they can be effective but if you have a larger pool you need much larger panels which will ideally be roof fitted. You can buy a base system and then add-on extra panels as required for the size of your pool.

Whether a solar pool heater will work for you really depends on your location and how long you want your swimming season to be.  If you can locate the solar collectors to get best results and are not looking to extend your season into the colder months then a solar pool heater is well worth considering. You might also consider a solar heater in addition to another form of heating so that you can make use of the free heating when it is available and back up with a gas heater or heat pump when it is not.

Pool Supply World have a range of solar heaters for above ground pools. CLICK HERE to see their range. You might also be interested in the range available at In The Swim.


AquaCal TropiCal Heat Pumps

The TropiCal range are AquaCal’s economy range of heat pumps. They are aimed at owners of above-ground pools or small in-ground pools. For 2017 a new look was introduced but the specifications remained unchanged.

Compared to the HeatWave SuperQuiet range they are less powerful, smaller, lighter, a bit noisier and have a lower throughput. There is only a single thermostat but they are significantly less expensive.

To buy an AcquCal TropiCal heat pump from Pool Supply World – Click Here.

There are five 60Hz models outputting 51k, 72k, 96k, 112k and 132k BTU with a COP ranging from 5.4 up to 6.0. Click here to see the product brochure.

(There are also five 50Hz models which are less powerful.)TropiCal Heat Pump

All the models feature:

  • Lockable, flip-out control panel protected against weather
  • Microprocessor controlled automatic defrost which allows operation down to the mid to lower 40s fahrenheit
  • Impact resistant rust proof cabinet
  • R410A environmentally friendly refrigerant
  • Variable warranty on other parts depending on where you live – details here

However the patented ThermoLink heat exchanger is only fitted on the top models. The basic versions have a Tube in Tube heat exchanger.

If you are looking to heat a small pool the TropiCal may be ideal for you. It is designed to give optimum heat output in a small footprint whilst having a long operating life and being resistant to wear and tear. Yes it is an economy model, and doesn’t have all the advanced features you find in the HeatWave SuperQuiet range, but that is reflected in the price making it good value for money.

To see prices at Pool Supply World – Click Here





How Do I Choose Between Manufacturers?

Having decided on the type of pool heater you want you are still faced with choosing between many different models from the major manufacturers. You might ask – which is the best model? However there is no easy answer to this.

In many ways it is like looking at models of cars from different manufacturers and trying to chose between them. There are pluses and minuses for all of them but they will all get you from A To B and once you get used to any of them you will probably be quite happy. So you end up buying where you can get the best deal.

With pool heaters you are likely to be quite happy with any of the models from the major manufacturers although you might want to consider the following:

Price – are you looking for the best pool heater regardless of price or does “best” mean a good value for money compromise. For example there are some highly energy efficient gas heaters available but they are very expensive (see why) so a cheaper, less efficient, heater may be better value.

Efficiency – the energy efficiency of pool heaters varies and is usually related to price i.e. the higher the energy efficiency the higher the price.

Emissions – For gas heaters low NOx emissions are a requirement in some locations which rules out some of the cheaper heaters.

Salt – Some heaters can be used with salt chlorinated pools but others are recommended for freshwater pools only.

Location – Some pool heaters can be used at altitude without any problem whilst others require modification to work above a certain height. Some put more emphasis in their design on handling the elements so are more suitable for exposed locations.

Connectivity – Some heaters offer reversible connections which can make all the difference if the heater has to be installed in a difficult space. Indeed in this case the actual size and shape of the heater might be a factor.

Cooling – If you are buying a heat pump you will need to decide whether you want the option of switching it to cooling in hot weather.

Having considered the above factors you should have been able to narrow down your list of possible heaters to buy. You should then look at what deals are available taking into account the price, any delivery charge and the warranty offered.

Are Pool Heaters Safe?

We have no hesitation is saying that a pool heater purchased from one of the major manufacturers and correctly installed and maintained is 100% safe.

Of course like any heating appliance they can be dangerous if mistreated. Gas heaters produce carbon monoxide so if installed indoors they must be properly vented and when installed outdoors proper thought must be given to the positioning (under house windows is not a good site). Adequate ventilation is essential so it is important to ensure that debris does not build-up around an outdoor heater. They must also be kept clear inside so an annual service by a qualified gas engineer is strongly advised.

Modern gas pool heaters feature a variety of safety features including ignition safeguards, pressure regulators, water pressure relief valves and automatic shut off controls all of which means that in use they are very safe.

Electric heat pumps offer little in the way of danger other than that they are electrical devices and must be respected as such but essentially electric shock hazard is avoided by construction and installation of the heater in accordance with strict electrical standards and codes.

Solar systems are also safe if properly designed and installed. It is quite practical to buy a system and install it yourself without creating any problems.

To ensure ongoing safe operation all pool heaters should be drained over winter to prevent any frost damage.

Many people consider making their own DIY pool heaters, usually solar systems and it is here that safety can be a question mark. All sorts of safety issues can arise such as pumping very hot water into the pool when first turned on.

In summary pool heaters are a safe way to increase the value you get from your pool but need to be properly installed and maintained. Only build you own pool heater if you are confident that you know what you are doing.


How To Minimize Energy Usage

Having got your pool heater up and running you should follow the tips below to minimize energy usage. Avoid bad habits developing which waste energy and hence push up your heating bills.

  • Use a pool cover whenever the pool is not in use. A good cover can reduce heat loss by over 50% because it vastly reduces evaporation. This also means you will need less pool chemicals and the cover will also keep debris out of the pool.
  • Do all you can to protect your pool from the wind. Even a gentle breeze at 5mph can lower the pool temperature significantly (again the big enemy is evaporation) so money spent on landscaping can be a great investment.
  • Keep a thermometer in your pool. This will easily enable you to see how the pool feels at a given temperature and you will be able to discover the lowest comfortable temperature for the water.
  • Set the pool heater thermostat for this lowest comfortable temperature. Heating the water any more will be throwing away money. It is a good idea to mark the thermostat dial at your desired setting or stick a reminder near an electronic control to try and prevent any accidental over heating.
  • If the pool is not going to be used for a few days turn the heater down to 70 degrees. For any longer of period a gas heater should be turned off as it will be more cost effective to let the pool temperature drop and heat it back up later. A heat pump is more suited to continuous heating but if you are going away for a couple of weeks you should still turn it off.
  • If possible return the warmed water in at the bottom of the pool rather than at the surface. This will heat the pool more effectively and efficiently.
  • Make sure that your heater is properly maintained and serviced as recommended by the manufacturer.  Also make sure that it is kept free of debris at all times.

What About Combining Types Of Pool Heaters?

If you want to get the maximum use of your pool but minimize the heating costs you might look at using more than one type of heater.

Perhaps the most obvious option here would be to have a solar heating system backed up by a gas heater or heat pump. This would mean that you could take advantage of free solar power when it is available but still have a means of heating the pool when the weather is poor, early morning/late evening and outside the summer months.

As well as keeping heating costs as low as possible this would also be an environmentally friendly option but of course it has the disadvantage of being considerably more costly to set-up so is not a viable option for many people. However it is worthwhile looking at you much energy you could generate using a solar heating system to see if it makes financial sense. Have a look at this site to see how you might do that.

Should I Heat My Pool All Summer?

If you have a pool heater you might wonder if it is a good idea to leave it running all summer. Unfortunately there is no simple answer to this. Of course you should firstly ensure you are using a good quality pool cover to conserve heat, it will then depend on:

  • The type of heater you have – a heat pump is best used for continuous heating whereas a gas heater is best for heating the pool up quickly. With a heat pump it is best to keep the pool heated unless it is not going to be used for a period.
  • Your usage pattern – If you like to swim in the early morning or late evening it will, in most locations, be more comfortable if you use the heater even in mid-summer.
  • The climate in your area – Clearly if you are in one of the hotter parts of the country heating may not be necessary all summer but of course the weather can always vary from the norm. If you have a top of the range heat pump remember that it can probably to reversed to cool the pool when required.
  • Location of the pool – The more exposed to the wind that your pool is the more heating it will require, regardless of the air temperature, as the wind causes evaporation which cools the water.
  • Your personal temperature preference – the most important point because the whole point of a pool heater is to help you enjoy the pool.


Efficiency Of Gas Pool Heaters

The efficiency of gas heaters has improved considerably over the years and today a typical gas pool heater is between 80% and 85% efficient. This means that this percentage of the energy consumed is transferred to the pool water. The remainder is lost in various ways, mainly through discharge into the atmosphere.

However, much higher efficiencies are possible. The Jandy Hi-E2 (now discontinued) was the first gas heater to offer an amazing energy efficiency rating of 95% and you may wonder why all gas pool heaters cannot offer this level of performance.Jandy Hi-E2

Well there is a negative side to high efficiency gas heaters and this was reflected in the price of this Jandy model which was significantly higher than other gas heaters.

At the 80-85% range the wasted energy actually provides a useful function and allows the heater to operate in a simple way. The products of combustion within the heater are principally carbon dioxide, carbon monoxide and water vapor and these must be discharged safely. The unused heat exits through the stack and in doing so provides lift for the waste gases and allows them to be efficiently discharged.

As the efficiency of the heater increases there is less unused heat and the waste gases are less efficiently discharged. At a certain point this process is no longer effective and condensation occurs within the stack. The result (called the condensate) is acidic which means that more expensive, corrosion resistant, materials have to be used and fans need to be installed to vent the gases properly. In addition the condensate must be collected and disposed of safely. All of this increases the cost of the heater and its installation.

Whilst high efficiency gas heaters are often appropriate for a commercial installations it is unlikely that they will be cost effective in a residential situation. Here the heater is not likely to be used enough for the increased efficiency to offset the higher price.

It is noted elsewhere on this site that the advantage of gas heaters is that they can quickly heat up a pool but where a pool is heated constantly a heat pump is a better option. This would indicate a limited market for high efficiency gas pool heaters.

Why A Pool Cover Is Essential

If you are using a pool heater to heat your pool and you are not using a pool cover you are wasting a large amount of energy and money.

The majority of the heat lost by a swimming pool is through evaporation and this can be made worse by a windy location.

The rate of evaporation from an outdoor pool depends on the following factors:

  • pool temperature
  • air temperature
  • level of humidity
  • wind speed.

You can help reduce wind speed with a correctly sited windbreak but for owners of pool heaters it is an unfortunate fact that the more you heat your pool the higher the level of evaporation will be. A pool cover is therefore essential.

The key requirement for a pool Pool Covercover is that it is a vapor barrier. By minimizing evaporation a pool cover significantly reduces heating costs (Click Here for more information and to see savings by location). There are various types of pool covers from simple manual options to expensive fully automatic systems.

All pool covers will reduce solar gain (absorption of energy from the sun by the water) but “Solar Covers” are designed to minimize this and you should consider this when purchasing. However it is still best to have the pool cover in place whenever the pool is not in use.

Of course there are additional benefits to using a pool cover:

  • Reduces consumption of pool chemicals
  • Reduces need to top-up the water
  • Keeps debris out of the pool

So if you have a pool heater, or are thinking about getting one, make sure you have a good pool cover as well.

Click Here to see examples of pool covers

Swimming Pool Temperature

What should the temperature of a swimming pool be?

Obviously the point of installing a pool heater is to make the pool comfortable for users, and operators of commercial pools generally find that the warmer it is the more people want to use it. Having said that individual preferences vary significantly, so there is no right answer as to the best temperature.

For residential pool owners cost will be a major factor, as energy costs quickly mount as you increase pool temperature. If you use a pool cover to minimize heat loss, just increasing the pool temperature from 78° to 82°F will more than double the heating bill in most locations (see  In fact, depending on your location, for each 1°F rise in water temperature your energy costs will increase between 10% and 30%.

It is also worth remembering that if a pool is kept very warm there is a danger of bacteria and other micro-organism multiplication becoming a problem. Also chlorine-based disinfectants become less effective as the temperature raises.

If you are active in the pool 78°F may be OK as this is the temperature recommended for competitive swimming to prevent swimmers from overheating. For general use 80° – 82°F should be acceptable but you may need to go as high as 86°F for babies or disabled people.

If you use your pool most days it will be worthwhile maintaining the temperature but if the pool will not be used for several days it is best to turn off the heater. You will use less energy in reheating the pool than in maintaining the temperature.