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 82%. 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.

Pool Heat Pumps – The Best Option?

Pool heat pumps are an increasing popular way for heating a pool. They are cheap to run and environmentally friendly but do have some disadvantages.

What is a Heat Pump?

A heat pump is a device for moving heat from one location to another. In the case of pool heat pumps heat is taken from the surrounding air and transferred to the pool water. The efficiency of air source heat pumps, like pool heaters, declines with the air temperature and ice formation is a problem at low temperatures.

A heat pump providing heating for a house is likely to be a ground source heat pump where the heat is taken from the ground using a length of well buried pipes. These have the advantage of being able to work at low temperatures but are expensive to install.

There are also water source heat pumps which take heat from one body of water and transfer it to another. These are rarely suitable as pool heaters but there are models available designed to take heat from a swimming pool to heat a spa.

How do Heat Pumps work?

We are all used to refrigerators and air conditioning units which work in the same way except they are used for cooling rather than heating. In fact the top of the range pool heat pumps usually have a reverse mode in which they cool the pool.Heat Pump

Heat pumps transfer heat by circulating a refrigerant through a cycle of evaporation and condensation. An electrically powered compressor pumps the refrigerant between the two heat exchanger coils. In one coil, the refrigerant is evaporated at low pressure and absorbs heat from its surroundings. The refrigerant is then compressed en route to the other coil, where it condenses at high pressure. At this point, it releases the heat it absorbed earlier in the cycle.

With any other type of heater it is impossible to have an efficiency in excess of 100% because energy output cannot exceed energy input. In practice, for example, most gas pool heaters are 80-90% efficient. The key point about a heat pump is that because it does not actually generate heat, the amount of energy (heat) produced is much greater than the energy (electricity) used. So even though a pool heat pump is powered by electricity it is still much cheaper to run than a gas heater.

How efficient are Pool Heat Pumps?

The efficiency of pool heat pumps is measured by their COP (Coefficient of Performance). This is a measure of how many units of heat energy are produced for every unit of electricity used. For a residential pool heat pump a value in excess of 5 is good. However a word of warning, the COP varies depending on the air and pool water temperature and relative humidity. It is normally measured at 80 degrees for air/water and 80% RH but this is not a defined standard.

Pros and Cons of Pool Heat Pumps


  • Cheap to run
  • Eco Friendly
  • No emissions


  • More expensive to buy
  • Less powerful than gas heaters
  • Not so good in cold conditions

Should you buy one?

If you want to extend the season during which your pool is usable and you heat the pool most of the time then a heat pump will be your best option. If you only want to heat your pool occasionally then you might be better with a gas heater because it will be able to heat the pool faster and its lower purchase cost will offset the higher running cost.

Click this link for information on Pool Heat Pumps that are available.

Pentair Heat Pump

The Pentair UltraTemp 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 75 – 140k BTU/hr two of which feature 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 UltraTemp product 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. It has a limited lifetime warranty on the heat exchanger and a 10 year warranty on the compressor. Reviews seem to be in the 4/5 star range.

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

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 the company 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.raypakpool heaters
  • Raypak Heat Pumps – There are four series of heat pumps, the Compact Series, the Classic Series, the Specialty Series and the Quiet Series. All 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. Some of the Specialty models can be switched into reverse to provide pool cooling in summer and also feature 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.

Raypak Heat Pump

Raypak now offer four ranges of Heat Pump:

The Compact Series – Three models outputting 50k, 66k & 83k BTU/hr (at 80F air & water and 80% RH) available with analogue or digital controls. The top model is also available with a Power Defrost option. This enables the heater to defrost itself whilst still heating the pool.

The Classic Series – Three models outputting 95k, 117k & 133k BTU/hr (at 80F air & raypakpool heaterswater and 80% RH) available with analogue or digital controls.

The Specialty Series – Eight models based on the two higher Classic models offering options like digital power defrost and cooling as well as heating. Three phase models are also available. Raypak say that this range is intended to offer features “not as commonly required”.

The Quiet Series – Raypak’s latest heat pump has been specially designed for quiet operation at only 59db.  There are three models outputting 95k, 117k, and 133k BTU/hr (at 80F air & water and 80% RH). These feature digital control and several extra features to ensure quiet operation such as a slow rotation fan motor and a custom engineered four blade fan. To see the Quiet Series brochure Click Here.

In terms of features, the Compact series do not have sound installation pads on the compressor nor internal bypass valving in the heater exchanger but other than that the basic features are the same. Click Here to see the Raypak Heat pump brochure.

A heat pump may cost more than a gas heater to buy but they are extremely efficient devices which can be 3 to 4 times cheaper to run than natural gas and 6 to 7 times cheaper than propane. They are not as powerful, so cannot heat a pool as quickly, so are ideal if you heat your pool constantly.

All these heat pumps are built to Raypak’s usual high standard to give “rock solid performance at an affordable price”.  All versions feature a titanium heat exchanger, to withstand pool chemistry and corrosion and use a Spiral Rifled design to maximize the surface area.

The cabinet is a polyester coated rugged steel construction. There are large air coils (made by Raypak themselves) to maximize the heating capability at low temperatures.

The standard Raypak heat pumps run of a single phase power supply but will need their own circuit which will require an electrician but it should cost less than a gas heater to install.

Raypak Analog Control PanelYou can opt for digital or analog controls on the cheaper models. Both allow you to set a separate pool and spa temperature and are compatible with remote controls. The analog control has 6 LEDs which tell you what is going on whilst the digital control has on board diagnostics which can provide detailed information to the owner or pool technician.  The Raypak documentation indicates that the digital version is superior but, strangely, the prices are similar.Raypak Digital Control Panel

If you are looking for a low cost, environmentally friendly way to heat your pool a heat pump is ideal. A Raypak heat pump is a great choice as it combines the latest technology with Raypak’s reliability at an attractive price. It should give you years of hassle free use of your pool.

These heat pumps are not as widely available as many pool heaters featured on this site but Pool Supply World offer a limited range and a wider range is available at INYO Pools.

Other Raypak Pool Heaters.

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.

Laars Pool Heaters (Jandy Pool Heaters)

Looking around the web there seems to be considerable confusion as to the correct name for this range of heaters. I have seen them under Laars Pool Heaters, Teledyne Laars Pool Heaters and Jandy Pool Heaters. The history of this is rather complicated but as I understand it the following is what happened.

Laars Engineers was formed in the late 1940s and pool heaters was one of its key products. It was bought by Teledyne in the mid 1960s and became Teledyne Laars. In 1996 Teledyne bought Jandy Industries and started marketing their pool heaters under that name (but sometimes including the Laars name). In the late 1990s Teledyne split the business up with Jandy taking the residential pool business and Laars Heating Systems (which still exists) the commercial side. In 2007 Jandy merged with Zodiac Marine to create Zodiac Pool Products and create “a major global supplier of pool equipment”. It had been the case that three of their four gas heaters were branded Jandy and one Zodiac but they now seemed to have settled on Jandy for all of them.

The current range of Jandy pool heaters comprises:

Jandy Hi-e2Jandy Hi-E2 – A top quality 350k gas pool heater for residential or commercial applications (it is ASME certified). The energy efficiency is an incredible 95% (and it is low NOx) putting it well ahead of other gas heaters. It is designed for long life and low maintenance and built using top quality materials. It has a dual thermostat for use with pool/spa combinations. Unfortunately all this is reflected in the price which is over twice that of the other gas pool heaters on this page.

Jandy JXiJandy jxi Jandy’s new range of gas pool heaters range from 200-400k BTU/hr with an efficiency of 83%. They have been designed with input from installation and service technicians and their key selling points are their small footprint, low weight and ease of installation and servicing.



Laars Pool HeatersJandy LXi – A range of gas heaters with outputs of 250k and 400k BTU/hr (models for natural gas and propane) with an energy efficiency of 88%. As well as being efficient these are also low NOx heaters exceeding the standard for low NOx emissions. These heaters have a feature rich control panel which can be mounted remotely.

Teledyne Laars Pool Heaters

Jandy Legacy – A range of gas pool heaters from 125k – 400k BTU/hr with models for natural gas and propane and with electronic or millivolt ignition. Energy efficiency is 83% but these heaters are not low NOx. The legacy heaters have a number of advanced features, are designed to be reliable and are relatively inexpensive, making then good value for money.


Jandy JE Heat Pump – The Jandy JE heat pumps were launched in 2013 and are available in four capacities 72k, 108k, 119k and 137k BTU/hr. The top model is also available with a reverse function for cooling the pool. The COP ranges from 5.5 to 6.3 and they all feature a proprietary titanium heat exchanger, dual thermostats and advanced digital control.

Which should you choose? Well it depends on how you will use your pool heater and also whether you are prepared to pay more upfront to make savings later. If you are going to heat you pool constantly a heat pump will be cheapest to run and the best buy long term. If you do not heat your pool constantly then a gas heater will get it up to temperature faster and the difference in running costs may be offset by the cheaper price. In this case the Hi-E2, good though it is, would seem to be rather over the top leaving the choice between the JXi, LXi and the Legacy.

If NOx emissions are an issue in your location then you would probably chose the JXi but if not the legacy would seem to be the best buy. Of course if you need a millivolt heater then the Legacy is the only option from Jandy pool heaters.

Jandy Legacy Pool Heater

The Legacy was Jandy’s only heater which was not low NOx rated and as such the only one available in a millivolt version. These heaters are increasingly difficult to find and are not available from any of the major suppliers. As such we have not included any link to purchase these heaters.

The Jandy Legacy pool heaters are available with five input power capacities ranging from 125k – 400k BTU/hr and use either propane or natural gas and have an efficiency rating of 83%.

Jandy Legacy HeaterThese pool heaters are energy efficient (but not as efficient as the more expensive Jandy pool heaters). They are, however, built to last, are user friendly and provide good value for money.

Features include:

  • Ceramic fibre combustion chamber for lightweight, compact design. So space should not be a problem when installing this heater.
  • Copper heat exchanger and Flo-Thru baffles provide efficient heat transfer minimizing the energy needed to heat your pool.
  • Polymer headers with CPVC universal union connections. These can be on either side for ease of installation along with the gas and electric connections, ideal where you are replacing an existing heater.

Jandy Legacy Electronic Model

Jandy Legacy Electronic Control Panel

  • Reliable hot surface ignition to provide trouble free operation even in extreme weather conditions.
  • Advanced Digital Control allows different temperature settings for pool and spa.
  • Self diagnostics – so you don’t need an expert to find any problems.

Jandy Legacy Millivolt Model

Laars Legacy Millivolt Control Panel

  • Standing Pilot Ignition.
  • Single Mechanical thermostat to allow setting of pool/spa temperature.
  • Easy on/off switch.

See Product Brochure for more information.

If you are looking for a pool heater which is good value, reliable, compact and will work in any conditions then the Jandy Legacy heater could be for you. You can get more efficient pool heaters and ones that are low NOx certified but these cost more.


Other Jandy Pool Heaters.


Jandy Hi-E2 – A Top Quality Pool Heater

The Jandy Hi-E2 (sometimes known as the Zodiac Hi-E2) pool heater is an excellent product that has been described as “the best pool heater money can buy”. It is certainly impressive but it must be said that it has a price to match. It is a 350k BTU/hr gas heater for either natural gas or propane.

The most striking thing in the specifications for the Hi-E2 is its incredible energy efficiency rating of 95%, which is way ahead of any other gas heater. This makes it significantly cheaper to run. It is also low NOx so it meets all environmental standards for NOx emissions.

Most versions of this heater are ASME (American Society of Mechanical Engineers) certified which means they can be used in commercial as well as residential applications (commercial includes pools in condominium and apartment buildings). Normally ASME versions of a pool heater are more expensive but here you are getting a product designed to stand up to more rigorous  commercial use.Jandy Hi-E2 Pool Heater

In fact the second major feature of this pool heater is that it is specifically designed for low maintenance and long life so it is ideal for use in extreme weather and in difficult or unusual locations. Features include:

  • Unique Forced-Air system which enables the heater to operate in extreme weather conditions are in difficult locations.
  • The combustion system does not require modification to operate at high levels. The efficiency is maintained but the heating capacity is reduced by about 3% per 1000 feet above sea level.
  • Heavy duty construction and high tech composite materials make the heater corrosion resistant , durable and dependable.
  • Self cleaning ignition, automatic venting and high velocity heat exchanger mean hassle free operation and reliability.
  • Dual thermostat means the heater can work with a pool and a spa.

Click here to see the product brochure.

The Jandy Hi-E2 is a commercial quality heater which is now available for residential use. It is built to last and should be still working years after its competitors have needed replacement. Its energy efficiency is remarkable so there will be a significant saving on gas (30% according to Jandy). However the price is more like that of a commercial pool heater and, whilst it is an excellent product, you have to balance the long term savings against the up-front cost.

At the time of writing (March 2018) it has become dificult to find these heaters although they are part of the current Jandy range. Our usual recommended suppliers do not have them in stock so the link below is to a site we have no relationship with.

To see Hi-E2 pricesCLICK HERE

Other Jandy Pool Heaters.



Hayward Pool Heaters

Hayward pool heaters are manufactured by Hayward Pool Products, a division of Hayward Industries, Inc., who have been manufacturing pool equipment for over 80 years. They are one of the large pool equipment producers and their range includes pumps, filters, pool cleaners, lighting, salt chlorine generators and pool heaters. The length of time they have been in the business indicates that they know what they are doing.

Their current range includes:

Hayward pool heaters for In ground pools

Hayward H SeriesUniversal H Series– A range of heaters powered by either natural gas or propane. Power levels range from 150K to 500K BTU/hr. The key benefit of these heaters is that they are energy efficient (84%) and produce emissions of NOx low enough to meet the most demanding local requirements including those of California and Texas. These heaters feature electronic ignition and a digital LED control panel, they are designed for ease of installation as connections can be made on either side.

Hayward H250H Series Millivolt – Again a range of heaters powered by either natural gas or propane. The available power levels range from 150 – 400k BTU/hr with the Hayward H250 being the most popular. Their energy efficiency is 81% and there is no claim as to low NOx. Millivolt heaters have a pilot light for ignition and to generate a small amount of electricity for the controls. The benefit is that they do not need an electricity supply so there is more flexibility in choosing a location.

HeatPro Heat Pump – A range of heat pumps rated at 95 – 140 BTU/hr. They all feature electronic temperature control and dual thermostat, so you can heat both a pool and spa. In addition they they are specially designed to operate quietly and reliably whilst being extremely energy Hayward Heatproefficient.

Which to choose – A gas heater will be cheaper to buy but will cost more to run. A gas heater will also warm the pool quicker. If you are going to heat the pool constantly during the season then a heat pump will be best, however if you are only going to heat it occasionally then a gas heater will be the better buy. If going for a gas heater you would go for the Universal H Series unless getting electricity to the heater is a problem. In this case the H Series Millivolt provides a good alternative.

Hayward pool heaters for above ground poolsHayward Swimming Pool Heaters

Above Ground H Series (Hayward H100) – A 100 BTU/hr gas heater available in 2 versions for either natural gas or propane. A simple plugin electricity connection is provided which provides direct-spark electronic ignition. Energy efficiency is 81%. Induced draft system means the heater is not affected by wind so it can be located where it is needed.

Hayward Heat Pump HP50TA – A 50 BTU/hr. heat pump specifically designed for above ground pools up to about 13k gallons. The features and benefits are much the same as the HeatPro shown above. This heater requires a 220 volt 30 amp electricity supply.Hayward Heat Pump

Which to choose – The same factors apply as for in ground pools above.

In general it is better to buy a more powerful heater than you think you need but if you choose correctly any of the above Hayward pool heaters will provide years of good service.