Do You Really Need A Pool Heater?

I was reading an article recently about the pros and cons of installing a pool heater which made me think. On this site we are so busy looking at pool heaters and the issues surrounding them that it is easy to overlook the basic question -  do I really need a pool heater? Of course there is no easy answer to this as it depends on individual circumstances such as location and period of use required.

There is no doubt that a pool heater will allow you greater usage of your pool and therefore a better return on the large investment you have already made in the pool. It will also make using the pool more pleasant, even during the summer.

However against this there will be an additional cost of buying and running a pool heater (even a solar powered one) and additional maintenance work and cost if the pool is operational for longer. Only you can make that decision which is summed up nicely in that article:

Weigh the costs and benefits of having a heated pool before you buy one. Are you willing to spend a little extra time and money for a lot more fun? Think carefully – don’t just go diving off the deep end!

To read the full article Click Here.

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 (a good example is the Jandy Legacy heater). 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 has 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 is reflected in the price of this Jandy model which is significantly higher than other similar models.

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 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 some are better than others 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 http://www.energysavers.gov).  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.

Are Electric Resistance Pool Heaters Worth Considering?

You can buy electric resistance heaters to suit all sizes of pools and spas but they are not as popular as gas heaters or heat pumps.

Coates offer a large range to cover virtually any residential or commercial application and are a good buy if you want this sort of heater but there are only a limited number of situations where they are advantageous compared to other types of heater.

Coates Heater Company has been manufacturing pool heaters since 1955. They still aim to build quality and reliability into every model to provide years of hassle-free performance.

If you have access to natural gas a gas pool heater will be cheaper to buy and much cheaper to run (although a propane heater will likely cost more than an electric heater).

A pool heat pump is the cheapest way of heating a pool and is the route you would normally take if you want (or need) to use electricity to heat your pool or spa.

The advantages of an electric resistance heater are:

  • Provides its quoted heat output regardless of the conditions – The same applies to a gas heater but a heat pump becomes less effective as the temperature drops and they will not work at all in cold conditions.
  • Pollution free – There is no need to worry about exhaust gases or air flow, which means that there is more flexibility in locating an electric resistance heater making it less obtrusive  and it may be safer if there are children about.
  • Relatively simple device – which should run reliably for many years.

The disadvantages of an electric resistance heater are:

  • Costly to run – running costs many times that of a heat pump or a natural gas heater.
  • Not as powerful as a gas heater – The Coates heaters range from 5.5 to 300 KW (for comparison purposes this is  19 – 1025 BTU) although the high powered ones are for commercial applications.
  • Environmentally unfriendly – unless the electricity is generated by renewable means.

If you have a spa that you want to use in colder weather and do not want a gas heater then an electric resistance heater may be ideal. However for heating a residential pool this sort of heater is unlikely to be a good choice.

To see the Coates pool heater range at Pool Supply World – CLICK HERE

What Size Pool Heater Do I Need?

A simple question but there is no simple answer.

Gas pool heaters typically range from 100,000 BTU/hour to 400,000 BTU/hour and all will heat your pool. Larger heaters will warm a pool faster and are slightly more energy efficient but, of course, they cost more.

The main alternative electric heat pumps are much less powerful 100,000 – 130,000 BTU/hour and cost more but they are very energy efficient  and therefore cheaper to run.

Below is a table giving some guidance based on the capacity of the pool or the surface area but this is very just a general guide. Much will depend on:

How you will use your pool heater

Will you want your heater to heat up your pool as quickly as possible at intervals or will you keep it heated all the time during the season. If the former you want the highest capacity heater you can afford so that the pool is ready for use quickly when you need it. If the latter you need a lower capacity energy efficient heater which keeps the pool ready for use at the lowest cost.

The location of your pool

Wind is the big enemy here. It will cause more evaporation which causes the pool to lose heat. So if your pool is in an exposed position your pool heater will have to work harder.  You also need to consider the lowest air temperature in the months you want to heat the pool and therefore the temperature raise required.

Your use of a pool cover

Use of a pool cover when the pool is not in use will dramatically reduce heat loss and therefore the demand on your pool heater.

Below is a simple table to give an indication of the size of gas heater that will be appropriate.  If you want to undertake a more detailed calculation have a look at this page.

Size Heater Gallons in Pool Sq. Ft. Surface Area of Pool
100 – 200 BTU heaters 1,000 gals to 10,000 gals up to 300 sq ft
200 – 300 BTU heaters 10,000 gals to 20,000 gals up to 500 sq ft
300 – 400 BTU heaters 20,000 gals to 40,000 gals up to 800 sq ft
400 BTU heaters 40,000 gals to 80,000 gals up to 1200 sq ft

In general it is best to work out what you think you need then get something slightly larger as, apart from the higher purchase price there is no harm in having a more powerful heater than you need.

If you want to heat your pool quickly you should go for a gas heater. However, before doing so you should look at the running costs compared to a pool heat pump as it may be that using a heat pump to keep the pool heated for longer periods would be more cost effective.

One of the major manufacturers Raypak has an interesting program for sizing a heat pump and showing the savings you will make. Click Here to visit this program,

Pentair MasterTemp

The Pentair MasterTemp series is a range of low NOx gas powered pool heaters with models from 175k to 400k BTU. There are models for both propane and natural gas including two “heavy duty” models for the latter.

To purchase a Pentair MasterTemp from Pool Supply World – Click Here.

Pentair MasterTemp Gas Pool HeaterDespite its functionality this pool heater is compact. It measures only 21″ x 21″ x 28″ (L x W x H) so is easy to install even where space is limited. A rotating digital display ensures that the controls are easy to see and use regardless of how the heater is positioned. The cabinet is a tough composite material which is not affected by heat or the weather.

However, the key selling points are:

  • It is certified for low NOx emissions so can be used where NOx emission restrictions are enforced.
  • It has an efficiency rating of 84% (using the standard copper heat exchanger) making it one of the cheapest to run gas heaters.
  • Heats up fast due to its fully pre-mixed system – which also contributes to its efficiency – so no waiting around for your pool to heat up.
  • Easy to operate – required temperatures can be set at the touch of a button and a digital display shows the water temperature, whilst five LEDs show you what is going on.

Pentair MasterTemp Brochure

There are also two “heavy duty” models which use a cupro-nickel heat exchanger. This stands up better to heavy use and poor pool chemistry but reduces the efficiency to 81%. ASME versions are also available for commercial use.

The Pentair MasterTemp heaters have a series of features designed to ensure safe operation but you can’t please everybody. For instance there is a factory set maximum water temperature which annoys some users (there are discussions online about how to get round this). However, overall this heater is a good choice if you need a low NOx gas heater.

Our recommended supplier is Pool Supply World who offer good prices which include shipping (often an expensive extra).

CLICK HERE to see their prices.

Other Pentair Pool Heaters.

Pentair Heat Pump

The UltraTemp Pentair Heat Pump is a high performance pool heater with the distinction of being the first pool heat pump charged with a non-ozone depleting refrigerant (R410A).

To purchase a Pentair Heat Pump from Pool Supply World – Click Here.

The UltraTemp heat pump range includes models ranging from 90 – 125k BTU/hr one of which features the option to reverse the system to cool the pool. Heat pumps are environmentally friendly as they are very efficient, do not create any emissions and this one is even environmentally friendly at the end of its working life. To see the 2012 Pentair pool heater brochure – Click Here.

Unusually you have a choice of color (Black or Almond) for the casing, which is a nice touch but not a major factor in deciding to buy one. Some of the features of this Pentair Heat Pump that are more interesting are:

  • Titanium heat exchanger to resist corrosion and ensure long life.Pentair UltraTemp Heat Pump
  • Scroll compressor which has fewer moving parts and increases efficiency and reliability.
  • Thermostatic expansion valve controls the refrigerant flow to maintain optimum efficiency over a wider temperature range.
  • Automatic defrost feature which allows the heat pump to operate at lower temperatures than would otherwise be the case.
  • Long life plastic cabinet which is resistant to corrosion, pool chemicals and the weather.
  • Easy to use LCD control panel so you know exactly what is going on.
  • Performance certified by AHRI (Air-Conditioning, Heating and Refrigeration Institute).
  • Very high efficiency – The COP (Coefficient of Performance) varies slightly but the base model has a rating of 5.8*.

* This means that for the heat pump outputs 5.8 units of energy (heat) for every one unit (electricity) consumed. This is because it is not using the electricity to generate heat but to transfer it from the surrounding air to the pool water. The COP will vary depending on the air temperature and water temperature here it is based on 80 degrees for both.

Of course we have to accept that a heat pump costs considerably more than a gas heater (which would also be more powerful) and that the performance of a heat pump drops when the air temperature gets colder. However, unless you only heat your pool occasionally the low running costs and environmental credentials of a heat pump cannot be ignored.

If you are looking for a heat pump this Pentair Heat Pump has much to commend it. It is designed for reliability and long life and its key selling point is its high efficiency.

Our recommended supplier is Pool Supply World which offer low prices which include shipping (which is an extra with many other suppliers).

CLICK HERE to see their prices.

Other Pentair Pool Heaters.

Raypak Pool Heaters

Raypak pool heaters are produced by Raypak inc. a California based company specializing in water heating systems including commercial boilers, water heaters and control systems, pool and spa heaters, and residential boilers. Founded in 1947 has grown rapidly and now supplies its products worldwide. Its goals have always been to achieve high quality, reliability and energy efficiency. The company was pleased to become the first boiler manufacturer to achieve ISO 9001 registration in 1996.

The current range includes:

  • Raypak Digital Heater – This is often referred to as the RP2100 although that is actually an older model. With models ranging from 200 to 399 BTU/hr, theRaypak Digital Heater Raypak digital heater is designed to minimize condensation and provide rust free waterways. It will provide years of trouble free use and be unaffected by all except the most extreme weather conditions. It is microprocessor controlled with electronic ignition and on-board diagnostic controls. Basically you just have to set the required temperature and the heater does the rest. There is also a low NOx version of this heater which exceeds all NOx emission requirements.
  • Raypak Millivolt Heater – This is very similar to the Digital heater except that it has a standing pilot light to provide ignition, uses a mechanical thermostat and has no diagnostics.
  • Raypak Heat Pump – The classic series heat pump ranges from 95 to 133 BTU/hr and all versions feature a titanium heat exchanger to withstand corrosion. There is a choice of analog or digital controls but in both cases you can control pool and spa temperature separately. The top model Raypak Heat Pumpcan be switched into reverse to provide pool cooling in summer and also features a defrost mode to prevent ice forming on the condenser.

Of these Raypak pool heaters which is best for you? Well the first thing to decide is whether you want a gas heater or a heat pump. Assuming that getting electricity to the pool location is not a problem, a heat pump will be best if you keep your pool heated most of the season. Although the purchase price is higher than a gas heater, a heat pump has much lower running costs. You might prefer a gas heater if you only heat your pool occasionally because gas heaters are more powerful and can get a pool up to the required temperature more quickly. They are also cheaper to buy and if they are not used a great deal then this advantage will not be wiped out by the higher running costs.

Assuming you are looking at a gas heater then you would go for the digital heater (or the low NOx version) if you can provide an electricity supply to the heater. If not you will have to go for the Millivolt heater.

Either way you will find that one of the Raypak pool heaters meets your needs.

Gas Pool Heaters – The Best Choice?

Gas pool heaters are very popular but these days might be considered environmentally unfriendly when there are more energy efficient ways of heating a pool.

However gas pool heaters are popular because they have a number of advantages:

  • Relatively cheap to buy and install – Obviously the cost depends on the size of your pool but gas pool heaters for above ground pools are available under $1000 and for in-ground pools under $1500. You will have to pay to have the gas and electric side of things professionally installed but the rest of the installation should be within the capability of someone who is reasonably handy.
  • Powerful – A key advantage of gas pool heaters is that they are powerful and can heat up a pool quickly (although we are still talking hours rather than minutes). Therefore they are ideal if you only heat your pool from time to time.
  • Energy Efficient – Gas heaters are much more efficient that they used to be with most falling in the 80-85% range. However you can buy a gas heater with an efficiency rating of 95% such as the Jandy Hi-E2.
  • Reliable – Although gas heaters are improving all the time this is a tried and tested technology. A properly maintained heater should give you many years of worry free pool heating.
  • Not affected by the weather – A gas pool heater will operate in all weather conditions.

Gas heaters usually are available for either natural gas or propane. In terms of performance it does not matter which you use but in terms of cost there is a major difference. Propane is much more expensive and you would only use it if natural gas is not available.

Gas pool heaters are available in both electronic and millivolt versions. The former are more popular as they feature electronic ignition and electronic controls. However to power these functions they need an electricity connection. Millivolt heaters, on the other hand, use a pilot light ignition system (which wastes energy) and have more basic controls but have the advantage of not needing an electricity connection.Pool Heater

Popular heater ranges include the Raypak Digital Heater, Jandy Legacy and Hayward H Series.

The main competition these days comes from pool heat pumps. These cost considerably more, are less powerful, are electrically powered and don’t work in very low temperatures. However, they can be several hundred percent efficient so that they are cheaper to run than a gas heater.

If you heat your pool constantly during the season then you should certainly consider a heat pump. If you do not heat your pool all the time then a gas heater will be your best option giving you the best balance between purchase/installation costs, heating power and running costs.

The table on this page gives approximate running costs for a gas heater by city.

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