How To Select The Right Heater for Your Swimming Pool

How To Select The Right Heater for Your Swimming Pool


Depending where you live, a heater could be a necessity if you’d like to enjoy your swimming pool as much as possible. The climate in some areas makes it harder to swim during the mornings and evenings due to cooler weather. Also, the summer doesn’t last too long in some regions. However, a heater will keep your water nice and warm and allow you to get the most out of your pool. If you’re thinking about purchasing a heater you’ll need to know what type and size will work the best for you.

Pool Size

Bigger is usually better when it comes to pool heaters. They’re rated by the number of BTUs they can put out. A BTU is a British Thermal Unit. One BTU can raise the temperature of one pound of your pool water by a single degree Fahrenheit. This means the more BTUs the heater generates the more water it can heat. They key here is to try and figure out how many BTUs it will take to heat your pool.  Once your water is the ideal temperature it won’t take much power to keep it that way, but it’s still a good idea to cover it with a solar blanket. This is because heat will escape from the water and the bigger the pool is the more heat you’ll lose.

It may sound complicated, but it’s not too hard to calculate your pool’s surface area.
For example if you have a round pool it will be the radius (1/2 diameter) x radius x 3.14

For a rectangular pool it is the length by the width

For an oval pool it’s 1/2 length x 1/2 width x 3.14

With a rectangular pool that has a rounded end-it’s the length times the width x 0.8

With a kidney-shaped pool you multiply the length by the width x 0.75

Pool Heaters and Heat Pumps

Heating Efficiency

Once you know the surface area of the pool you’ll need to decide on your ideal water temperature. If you’d like the water to be 80 degrees and it’s currently at 60 then you’ll want to raise it by 20 degrees. You can then check out a heating guide and see how many BTUs are needed to raise your pool’s water temperature by the desired number of degrees. For instance, a pool surface of 1,000 square feet will need 263,000 BTUs to lift the temperature by 20 degrees.

When you know how many BTUs are needed for your pool you can start shopping for a heater. Each heater will come with an efficiency rating. The rating represents the percentage of energy the heater transfers to the pool water for each BTU. The law requires that all pool heater’s have a minimum efficiency rating of 78 per cent. As an example, if you have a pool heater that can produce 300,000 BTUs and the efficiency rating is 85 per cent then it can generate 255,000 BTUs per hour.

It’s always a good idea to choose a heater that can handle a surface area bigger than your pool’s. Your pool heater can never be too big and if it produces more BTUs it will heat your pool quicker than a smaller heater. If the water is heated at a quicker rate it means the heater doesn’t have to run as often and its life span will typically be extended.

Choice of Swimming Pool Heaters

There are various types of pool heaters to choose from. The differences generally have to do with the type of fuel used, the type of heater ignition, the emission level produced by the heater and the elevation rating of the unit. The most common type of fuel choices are liquid propane and natural gas. However, you will also find electric and solar models as well as wood-burning versions. You can select the type of fuel based on the price and availability in your area.

When it comes to the ignitions, the choices are electronic and millivolt pool starters. With a millivolt system there’s a standing pilot light which must stay lit. However, a pilot light isn’t needed with an electric starter. If the pilot light goes out on the millivolt model you’ll need to re-light it.

As for the pool-heater emissions, there are normal emission models and Low NOx versions with the low NOx heaters producing fewer emissions. In general, Low NOx heaters are more efficient. If you happen to live in a region that’s 2,000 feet or higher above sea level you’ll need a special type of pool heater for the altitude because of the oxygen-level difference. In addition, pool heaters will have specifications regarding ventilation and clearance areas.

Solar Heaters

Solar heaters are becoming more popular since they don’t cost much to operate, they’re quiet and there are no emissions. However, since they need direct sunlight to run on they may not be a good choice in all areas as you may need a backup heater. The system consists of a solar collector, pump, and filter with the solar collector heating the water. A solar collector can also consist of plastic or copper piping, flat plate panels, or vacuum tube arrays.

Solar pool heaters Canada

Electric Pump Heaters

Even though electricity usually costs more than propane and natural gas an electric pump heater uses less power. This type of heater is best suited for use when the air temperatures is over 45 degrees as it is more efficient when the temperature is higher. The unit needs to be placed level on a concrete pad and it’s plugged into a 220V electrical outlet. Electric models aren’t very effective in colder temperatures, but there are no emissions.

Raypak electric pool heater Canada

Wood-Burning Swimming Pool Heaters

A wood-burning heater is akin to an outdoor furnace. It burns wood in a combustion chamber and the water is heated in a circulation pipe. However, you’ll need to add firewood about once an hour when heating the water.

wood burning pool heaterRecap

Remember, you can never have a heater that’s too large. Before making a decision you should you’re your region’s climate into account. If you receive a lot of sunshine you may feel a solar model is the most cost-effective. An electric version is efficient, but electricity is expensive. Propane and natural gas versions use cheaper fuel, but use more of it. However, they can heat your swimming pool quicker tan the other options.


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