Swimming Pool Heaters
Buying Guide

If you have a swimming pool, the logical investment decision is to buy a water heater. Although the perfect water temperature is a matter of personal choice, you will certainly extend the use of the pool by installing a heater. No matters of the weather, cooler or warmer, swimming pool heaters provide comfortable temperature for a great swimming experience.

Let’s go to the market to see what is available.

The operating principle of the pool heaters is similar from one type to another. Unit produces heat to warm water, which comes in from the pool. Water passes through a heat exchanger, and heated water goes back into the pool.


The first impression is supply abundance – there are so many models and options. Swimming pool heaters can be classified in four main types: electric resistance heaters, heat pumps, gas heaters (natural gas or propane) and solar heaters. Well, five... the fifth type is wood burning heater, but it is the least convenient option.

Each type has pros and cons. To decide which one fits your needs, learn something about them. Here are some customers’ testimonials and expert opinions.

Electric heaters

Ecosmart electric pool heaterElectric resistance heaters are the cheapest to buy, but the most expensive to operate. These heaters are simple, compact, clean and reliable, suitable for all weather conditions.

Electricity price is the reason they may be recommended for spas or small above ground pools only. You may find a model for $500 and don’t hesitate to buy it if your needs are moderate or low.

Heat pumps

Hayward electric swimming pool heatersHeat pumps are popular because of their high efficiency. They also use electricity, but on the innovative way by moving the warm air instead of generating the heat, which results in huge savings.

Modern materials and technology allow heater to be durable and environment friendly. The initial investment is high, $2000 and up, water is heating slower, air temperature must be above 45 degrees F... Nevertheless, you will forget all that at the end of the month when you receive electricity bill. Heat pumps are ideal for frequent use, if you want to enjoy your swimming pool on a daily basis.

Gas heaters

Hayward gas pool heaterGas pool heaters are somewhere between the previous two. Slightly less expensive than heat pumps, natural gas and propane units are superior when you expect fast work regardless the conditions.

However, gas prices are not as affordable as used to be. Several times higher monthly costs than the heat pumps’ operating charges may influence the decision. This type of pool heaters is meant for the homeowners who are using the pool occasionally. When combined with the above heat pumps, you will get the most energy efficient way to heat and cool the swimming pool either in warm or cold weather.


Solar pool heaters are ideal for sunny climates, but even there users have to prepare a secondary heating source for cloudy days. Solar water heater systems are the most expensive solution to buy, they work slowly, with almost no costs to operate and are environment friendly.

The longest lifespan is found on solar 15-20 years, then heat pumps 10-20 years while the shortest lifespan is found on gas, 5-years.

The best starting point for decision-making is to put on paper your needs, wishes and specific conditions.

How to choose the heater based on the pool size

The first thing to figure out is the size of your swimming pool and desired water temperature rise. According to these numbers, you will decide about the required performances of the water heater. There are calculation methods that include the surface of the pool, its volume, shape, the difference between the water and surrounding air temperature... but in general, you will need a 200-300K BTU heater to heat an average 10.000-20.000 gallon pool. The time needed for heating should also be taken into account. According to the company that produces popular Hayward pool heaters, model H250 which has a gas input of 250,000 Btu/h will be able to heat 10,000-gal pool for approximately 10 hours, and raise the pool temperature 30 F. When calculate, it is recommended to go one size larger – more powerful water heater will do the job faster, with lower energy consumption.

The next important calculation is price and availability of the fuel at your location. And, of course, your budget. Don’t forget the installation price.
Make sure that you have done all to prevent unduly water cooling. Consider investment in thermal pool cover or solar blanket. According to some experts, it can reduce the heat costs by as much as 60%.

Popular brands

Once you have decided what type of pool water heater is the best one for you, take a closer look at the models, and compare them. Here is the list of popular models:

  • Hayward

  • Aquacal
  • Raypak

  • Jandy

  • Pentair


Check the BTU (measure of heat output i.e. energy-producing capability) of the unit, and energy efficiency (in COP units). Gas units have different types of ignition systems (millivolt vs. electronic start heaters).

Review usage options: control panel, self-diagnostics capability, safety sensor function... Check installation prerequisites and mounting kit. Ask about warranty availability.

If you are not sure about measurements and features, ask an expert to help and a pool heating audit. He may add into calculation factors invisible to you and recommend a solution according to the latest market findings.

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