Pentair MiniMax 100 Review

Note: This heater was discontinued after the 2014 season and is no-longer available (although you can still get parts). The replacement is the Mastertemp 125 – click here for more information.

The Pentair MiniMax 100 is a high performance 100k BTU gas heater designed specifically for above ground pools and spas. There are four versions:

  • Natural gas with electronic ignition,
  • Natural gas with millivolt ignition,
  • Propane with electronic ignition,
  • Propane with millivolt ignition,

although prices are very similar for all models.

Pentair Minimax Pool HeaterIf you just want to heat a smaller above ground pool or a spa the heating capacity of the MiniMax is ideal, there is no point in paying more than you need. As a guide if you have a 500 gallon pool this heater can raise the temperature up to twenty degrees in an hour. So even if you only heat the pool intermittently, maybe just at weekends, it will soon be ready for use.

The Pentair MiniMax heater is a compact self contained unit which is easy to install and maintain. Its key features are:

  • High thermal efficiency means less heat lost into the air thereby keeping costs as low as possible.
  • Patented thermostatic bypass valve minimizes calcium scaling and corrosion thereby maintaining the efficiency and prolonging the life of the heater.
  • Uses a proven burner system for trouble free operation.
  • Flow valve senses water flow and controls this to maximize heating efficiency.
  • Durable weather proof housing protects the heater from the elements.

It is also service friendly, quiet in operation and has user friendly controls.

The MiniMax 100 is the ideal way to keep your spa or above ground pool at the optimum comfortable temperature so that the whole family can enjoy the pool throughout the day and outside the normal swimming season.


Other Pentair Pool Heaters.

Choosing A Pool Heater

An unheated swimming pool can only be used when it is warm enough, so your use of your pool can be increased by installing a pool heater. Pool heaters are available from several different manufacturers and in a range of power levels, which means that choosing the right one for you is not easy.  You also have to decide if you need a gas pool heater, a pool heat pump or whether you location is suitable for a solar pool heater.

Pool heaters come in a range of types and capacities and you need to carefully select the right one for your pool. This is not as easy as it seems as although it is easy to calculate the amount of water to be heated there are other factors to take into account which are harder to quantify.

Heater capacity is quoted in BTUs per hour. For example the Raypak 2100 models range from 206 – 406k BTU and the Hayward H Series ranges from 150-400k but the Hayward H250 seems to be most popular. (One BTU is the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit.) A larger heater will be slightly more efficient but, at the same time, it would be pointless to spend more than is needed.

The factors to take into account are:

  • Size of pool – The volume of water in the pool and the surface area.
  • How you will use the pool? – Will you be heating the pool constantly or, for instance, just at weekends? If you are heating the pool intermittently then you will need a larger heater than if you are heating the pool constantly.
  • Temperature increase needed – What temperature do you want the water to be heated to and what is the air temperature in the coldest month you will be heating the pool?
  • How the pool is located – How exposed is the pool to the wind? Wind is a big enemy of heated pools because it increases evaporation and hence heat loss. The pool should be sheltered from the wind if at all possible.
  • Will you use a pool cover? – Pools that are not covered can lose 4° F to 5° F overnight in most locations. Use of a pool cover will reduce that by about 50%.

For an average location an indication of the requirement for a pool heater can be calculated as below:

Area of pool (sq. ft.) X Temperature increase needed in coldest month X 12

Of course this cannot consider the specific factors of location and use of an individual pool. In general you are better off buying a slightly bigger heater than you think you need. It will warm up the water more quickly and with less strain on its mechanics, which should help it last longer.

Extend The Swimming Season With A Pool Heater

Installing a swimming pool is a large investment and the cost of maintaining it is not insignificant. However, the reward that can be obtained from having your own swimming pool is not financial (unless you are renting it), it is enjoyment. However in many cases the pool is only usable in the warmer months, as it is too cold the rest of the time, and this limits the return on that big investment. The solution is a pool heater which will extend the times the pool is usable. This table shows the likely costs of using a gas heater by city.

Pool heaters simply make sure that the water is kept at a specified temperature so that it is comfortable for swimmers at all times. The recommended temperature for a pool is usually set at 78 degrees but some people, who prefer to swim in warmer water, set their pool heaters to up to 80 degrees.

The types of pool heaters normally seen in residential applications are gas powered, heat pumps (electric) and solar powered. Choosing which type of pool heating system to install in your own pool is an important decision as there are certain factors to consider like the design of your pool and the house, the pool’s location, and of course your budget.

The most common type is the gas-fired heater which uses natural gas or LPG and is the least expensive to purchase although can be costly to operate, particularly with LPG.

The following are examples of gas pool heaters:

  • Pentair MasterTemp 125 – Pentair’s lastest heater designed for above ground pools/spas. Aims to deliver the sort of energy efficiency and advanced features previously only seen on more expensive models.
  • Raypak 2100 – The design enables it to withstand all sorts of weather. Just set the required temperature and forget it.
  • Hayward H Series – A top quality range of low NOx products using materials that will enable them to offer reliable and efficient heating for many years.

Another type of pool heater is the electric heat pump heater. This is usually more expensive to purchase but running costs are low. This is due to them not generating heat but simply moving it from the air to the water. In fact some “heaters” can be reversed in summer to cool the water.

There is also the solar pool heater that uses energy from the sun. While it uses renewable energy sources, it is costly to setup. Additionally, it requires a solar collection area that is equivalent to the surface area of the pool that will be heated. Also there is still an energy cost as electricity is required to pump the water through the solar panels.

While a heater is a significant additional investment, it will greatly enhance the usability of your pool by extending your swimming season.

Hayward Heat Pump Pool Heater Review

Hayward HeatPro Range For In-ground Pools

The range comprises eight models ranging from 95k to 140k BTU with a COP of 5.7 (measured at 80 degrees air/water and 80% relative humidity). They all feature electronic temperature control and dual thermostat, so you can heat both a pool and spa. The smaller model requires a 38 amp supply and the others a 42 amp supply. Two of the models can also cool a pool in hot weather. The range was last revised for 2016 and includes round and square models. To see the product brochure – Click Here.

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

The key features of these heat pumps are:Hayway Heatpro heat pump

  • Quiet Operation – Special fan design improves airflow whilst operating quietly. The acoustic compressor cover further reduces noise.
  • Corrosion Resistant – The Ultra Gold corrosion resistant coated evaporator coil fin gives increased durability near the coast or other corrosive environment. Plus the injection molded shell is resistant to UV, rust and deterioration in general.
  • Trouble Free Operation – The titanium heat exchanger is designed to ensure trouble free operation even in harsh conditions.
  • Digital Control Panel – Easy to use digital display with continuous pool temperature display, temperature set point lock and self diagnostic facility.
  • Easy Installation and Servicing – The unit has a compact footprint, simple plumbing connections and is designed for easy access for servicing.heatpro square

If a heat pump is suitable for your needs the Hayward HeatPro range is a good choice both in a new installation or to replace an existing heater. It should help you to enjoy your pool for many years to come. As with the HP50TA above, user reviews for this range of heat pumps are good.

Our favorite supplier – Pool Supply World – carries the full range. Their service is good and their prices  (taking shipping into account – which they include) are always close to the best.

Summit Heat Pumps

Summit was acquired by Hayward in 2008 but they continued to sell these heat pumps under the Summit brand until 2015. You do occasionally still see them for sale so I have left this information here. The current Summit heat pumps are aimed at the trade only.

There are 4 models ranging from 65 – 140k BTU with a COP of 6.0 – 6.2 (at 80-80-80). In terms of specification they are very similar to the Hayward HeatPro but cost a bit more.

The Summit brand suggests higher quality and this is backed up with claims such as “ All the Summit heater parts and accessories are superior in quality….”.  Hayward Summit Heat Pump

The key features are much the same as these of the HeatPro:

  • Quiet Operation
  • Titanium heat exchanger
  • Corrosion Resistant
  • Electronic Controls

Plus: a thermostatic expansion valve which delivers the correct amount of refrigerant for optimal performance. This maximizes performance in low

Reviews of the Summit heat pumps are difficult to find but generally seem to be good. There was little change to the range since Hayward’s involvement so at least it is a tried and tested product. It did seem that Hayward were competing with themselves here and Summit does not feature in the current range but these heat pumps can still be found for sale.

See other Hayward Pool Heaters.

Hayward H100 Above Ground Pool Heater

This heater has now been discontinued.

The Hayward H100 is a natural gas or propane heater designed specifically for above-ground pools and spas. As a general guide it will suit a pool up to 24 x 16 feet.

Installation of the heater is easy thanks to its CPVC plumbing capability which comes ready to plumb into your existing pool filtration system. The package comes with a 120V electric cord which can be plugged in anywhere which just leaves the gas side of things which must be left to a professional.

This pool heater features:Hayward H100 Pool Heater

  • electronic, direct spark ignition system and a rapid-heat combustion chamber which delivers optimum performance and extended life.
  • energy-efficient FireTile® lined combustion chamber that provides 81% thermal efficiency which keeps energy costs as low as possible.
  • an integral induced draft system which makes this heater completely impervious to any high wind situations.
  • a rust resistant water path with polymer header assembly which protects the unit from corrosion.
  • jet-ported Eugenox burners which provide long life and easy maintenance.
  • single piece copper header/heat exchanger which guarantees leak-free performance.

The Hayward H100 will allow you to enjoy your above ground pool even more. It will lets you swim, comfortably, long after your friends have abandoned their pools for the season. It will also lengthen your swimming day – so you can exercise early each morning, or entertain later each evening. To view the product brochure Click Here.

There are many very positive user reviews of this heater but also some poor ones (concerning reliability). Inevitably every heater gets some negative reviews but in this case the balance is slightly concerning.

Other Hayward Pool Heaters.

Why Install A Pool Heater?

In these environmentally conscious times you may wonder if installing a swimming pool heater is a good idea. Isn’t it just wasting energy, being environmentally unfriendly and at the same time very expensive?

Certainly these points Pool Heatersneed to be considered but a pool heater can greatly increase your enjoyment of your pool (and the investment in it) by making it useable all day and extending the “swimming season”.

There can also be significant health benefits as swimming is very good exercise particularly for people who suffer from arthritis and muscular diseases. A heated pool also prevents chilling and the problems caused by the loss of too much body heat which can affect very young children and the elderly.

There are a number of steps you can take to minimize energy usage so that costs are controlled:

  • Type of Heater – This is probably the key decision. At present gas heaters (such as the Raypak Digital Heater) are the most common type but they can be expensive to run (particularly propane heaters). The best from an energy and running cost point of view are now electric heat pumps. Normal heaters can never be more than 100% efficient (gas heaters are about 80-90%) but heat pumps (such as Hayward Heat Pumps) can be several hundred percent efficient (i.e. you get several times more energy out than you put in) because they are not actually generating heat they are moving it from one place (the surrounding air) to another (the pool water). Heat pump heaters are not as powerful as gas heaters so need to run for longer periods but they are still much cheaper to run.
  • Pool Temperature – You want the water to be comfortable but don’t heat it any more than you need to. 78 degrees is often recommended.
  • Use a Pool Cover when the pool is not in use – This is essential as a pool cover can reduce heat loss by 50%. The key function of a pool cover is to stop evaporation as evaporation causes significant cooling. The cover will also help preserve pool chemicals.
  • Shelter the pool from wind – Even a gentle wind can lower the pool temperature significantly.
  • Proper Maintenance – Make sure the pool and its heating system is properly maintained.

If you follow the points above you will find that a pool heater is a very worthwhile investment.

Hayward H250 Pool Heater

The Hayward H250 is part of the Hayward H-Series Millivolt pool heaters range which may not represent the very latest in heating technology for swimming pools and spas but are still a good choice if you require a millivolt heater (if there is no electricity supply).

To purchase the Hayward H250 from Aqua Swimming Pool Supplies – Click Here.

NOTE – This page relates to the Hayward H Series Millivolt Heaters. If you are looking for the Hayward Universal H Series low NOx, including the H250FD, please Click Here.

To see the Hayward brochure Click Here (there is a small section on the millivolt heaters towards the end – note this is not the current brochure for the Universal H Series).

H-Series Millivolt heaters are gas heaters (models for natural gas and propane) and are easy to install and maintain, thanks to their low profile, light weight and CPVC plumbing capabilities. Hayward have been reducing the number of medels available in this range and presently only list one but you can still buy the full range from 150 – 400k BTU/hr. Of course these are not low NOx so will not be allowed in some locations.

The Hayward H-Series Millivolt heaters include a wealth of features to deliver precise water temperature control and achieve the ideal swimming pool and spa comfort level. They are also built to last.

Features include:Hayward H250 Pool Heater

  • Single header “V” baffle design heat exchangers which facilitate long life, fast heating and virtually no condensation.
  • Heat exchangers constructed with highly resilient Cupro Nickel for greater durability and longevity.
  • Rust resistant water path with injection-molded polymer header. This provides improved by-pass control and extends life by providing additional protection from the damaging effects of corrosion from high flow conditions and from occasional pool chemical imbalances, making the unit ideal for salt-chlorinated pools.
  • Burner system constructed of stainless steel and can easily be removed for cleaning and maintenance.

Together, these added technological improvements ensure that your Hayward heater outperforms and outlasts expectations. However, it has to be said that Millivolt heaters are old technology and are not allowed in some states. You would only buy one if it would be prohibitably expensive to install an electricity supply.

These heaters are not widely available. However we did find a good range at Aqua Swimming Pool Supplies (February 2018). To see their prices click the link below:

CLICK HERE to see prices for the H-Series Millivolt heaters


Other Hayward Pool Heaters.

Raypak RP2100 Digital Heater – Tells You What Is Happening

The Raypak RP2100 was replaced by the current model, commonly known as the Raypak Digital Heater, a few years ago (but the RP2100 name is still commonly used). The popular standard range offers four power levels ranging from approx. 200 – 400k BTU for use with natural gas or propane and has an energy efficiency of 82%. The standard models have a copper heat exchanger but there is a Cupro-Nickel option to cope with adverse pool chemistry. There are also ASME approved models for non-residential applications.

As you might expect from its name the Raypak Digital Heater provides a sophisticated control panel Raypak Digital Control Paneland electronic ignition. This requires a mains electricity connection but to cover cases where this is not possible there is a Millivolt version (see Raypak Millivolt Heater) but this can only offer basic controls.

The standard models are not suitable where low NOx levels are a requirement but there are versions of this heater which are low NOx (they cost a bit more) but these are only for use with natural gas.

To see the product brochure Click Here.

Click this link to purchase a Raypak Digital Heater from Pool Supply World.

This Raypak pool heater will help you enjoy your pool at any time of the year. It features a microprocessor based thermostat control.  This control allows you to set your pool temperature exactly at your preferred setting by just pressing an up or down temperature control key. The digital display lets you see a constant reading of your pool’s water temperature. You just need to set it and forget it. It is that simple.Raypak Digital Heater RP2100

Maintaining or troubleshooting this pool heater is made easy. Its diagnostic controls let you and your pool technician know what is exactly going on with the heater, all the time. If you encounter a problem with the heater, the digital display will reveal to you where the problem is. An additional benefit is that this heater is compatible with most major brand remote control systems on the market.

The Raypak Digital Heater has the best outdoor design out there in the market today. With over 50 years under their belt in building and designing gas heaters, Raypak have put all their experience into this heater design. Fans are no longer needed to prevent drafting problems, This heater was designed for the outdoors and has an exclusive low profile design. A lot of thought and planning has been put into the heater’s design so that it can protect itself from the environment and prevent itself from being smothered by  falling leaves, wind, airborne debris, rain, downdrafts, updrafts, sleet, and snow.

Raypak Digital Pool Heaters were designed to withstand extreme weather conditions and ensure uninterrupted heating performance. They are manufactured at an ISO 9001 registered manufacturing plant. The pool heaters are tested by CSA to the ANSI Z21.56 standards. This demonstrates the quality that these heaters deliver and why it is that they are one of the leaders in market. The Raypak assembly process includes six final assembly quality control checkpoints that ensure that each and every pool heater delivers its peak performance.

The standard models feature a Copper Fin Tube heat exchanger although Cupro nickel is available as an upgrade if needed. Protection against condensation,sooting and scale build-up is provided by the Unitherm Governor which balances the water temperature/flow. The heater is capable of handling a flow rate up to 125 GPM.

For most residential installations the standard Copper Fin Tube heat exchangers will be the best (and cheapest) option and the Digital Heater is definitely preferable to the Millivolt version. The heater is not “state of the art” but it does offer a lot for the price and is popular with users.

We recommend our favorite supplier Pool Supply World who carry a large range at good prices (and also quote for models for use over 2000ft) with free delivery and a 5 star service.