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Best Pool Heaters

How to choose without a brand ranking

We do not rank brands or name a single winner. Pool heaters from established makers share similar designs, and the best choice for one yard can be wrong for the next. What separates a good purchase from a regretted one is fit: the right type, the right size, the right fuel, and a dealer who will be around to service it. This page gives you a repeatable way to compare any shortlist of models.

Step 1: decide the heater type

Start with how you swim. If you want warm water on short notice, such as a weekend pool that sits unheated midweek, a fuel-burning heater is usually the practical choice because it adds heat fast regardless of air temperature. If you swim most days through a long season and are willing to keep the water warm continuously, an electric heat pump often costs less to run. If you have a large, sunny, south- or west-facing roof and are happy with a gentler boost, solar can extend the season with no fuel bill. Many owners combine approaches, for example a heat pump plus a cover, or solar plus a small gas unit for cool snaps. Our heat pump vs gas pool heater page goes deeper.

Step 2: size for your pool, not the showroom

Size comes from surface area, the water-to-air temperature gap, wind exposure and how quickly you need heat. Run the pool heater size calculator or the pool heat pump size calculator before you shop. A heater that is too small for your coolest month will run for hours and still fall behind; one that is far too large may need a bigger gas line or electrical service than you have. Write down the output you need at your conditions, not just a nominal rating.

Step 3: read the spec sheet the right way

Spec sheets use different test conditions, so compare like with like.

• Gas and propane heaters list input BTU/h and a thermal efficiency. Multiply the two for approximate output. Check whether the unit is approved for natural gas, propane or both, and whether a conversion kit is required.
• Heat pumps list output and COP at one or more air and humidity conditions. Look for figures near your cool-month air temperature, not only the warmest rating. Check the minimum operating air temperature.
• Solar systems depend on collector area, orientation and sun. Ask for collector area as a share of pool surface area and the expected temperature gain.
• Electrical and gas needs include breaker size, wire gauge, gas line capacity and venting. These drive installation cost as much as the heater price.

Step 4: compare running cost honestly

Use your actual utility prices in the pool heater operating cost calculator. Include delivery charges and any seasonal rate. If propane prices swing in your area, run a high and low case. A heater that is cheaper to buy but costs more each month can lose its advantage within a few seasons, and the reverse is also true for occasional users.

Step 5: weigh durability and water chemistry

Heat exchangers face constant contact with treated water. Some models offer exchanger materials marketed as more resistant to corrosion; salt systems and aggressive water chemistry make this matter more. Read the warranty for what voids it, which often includes poor water balance or improper installation. Keep pH, alkalinity and calcium hardness in range and follow chemical labels; see pool heater lifespan for why chemistry drives longevity.

Step 6: check service and warranty

A heater is only as good as the help you can get when it stops in July. Ask local dealers and service companies which models they stock parts for. Read warranty terms on length, what parts are covered, whether labour is included and whether registration or professional installation is required. A model your local tech knows well can be worth more than a slightly better spec sheet.

Step 7: get comparable quotes

Ask two or three licensed installers to quote the same scope. A good quote lists the model and size, gas line or electrical work, permits, pad, plumbing and bypass valves, venting, removal of the old unit and start-up. Our pool heater installation cost guide explains each line so you can compare quotes fairly.

Worked example: narrowing a shortlist

Figures below are illustrative examples (2026-10-29), not quotes or guarantees.

Assumptions: 16 × 32 ft pool, 512 sq ft, swimming May to September, coolest-month nights around 58°F, target 82°F, natural gas available at the street, average wind. Holding need ≈ 512 × 24 × 12 ≈ 147,000 BTU/h of output uncovered, or about half with a nightly cover. The owner swims daily and adds a cover, so a heat pump with roughly 75,000 to 100,000 BTU/h of output at 60°F air is one path, and a gas heater of roughly 150,000 to 250,000 BTU/h input is another. Running the cost calculator with local prices, plus quotes for a gas line extension versus a 240 V circuit, decides the shortlist.

Common buying mistakes

• Choosing by maximum BTU without checking output at your cool-month conditions.
• Skipping a cover, then oversizing equipment to make up for evaporation.
• Forgetting that a new gas heater may need a larger gas meter or line.
• Assuming a heat pump will reheat a cold pool overnight.
• Letting water chemistry drift, which can shorten exchanger life and affect warranty.

Safety reminder

Gas heaters must be installed by a licensed HVAC or pool professional; never attempt DIY gas work. Heat pumps on 240 V need a licensed electrician, proper bonding and a disconnect. Follow pool chemical product labels exactly.

FAQ

Why don't you name the best brand?

Because fit, local service and your prices matter more than any brand ranking, and we have no way to test every model in your conditions.

Is a higher efficiency gas heater worth it?

It can be if you heat many hours a season; the cost calculator shows the difference at your gas price.

Can I mix solar and gas?

Yes. Many systems use solar as the main source and a fuel heater as backup; plumbing must be designed by a pro.

Where can I compare two specific makers?

See Raypak vs Hayward for a neutral checklist approach.

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