Pool Heater Basics: Gas vs Heat-Pump Pool Heating in Ontario
Gas pool heaters heat fast on demand; heat-pump pool heaters cost less to run over a long season. Here's how each works and which fits an Ontario pool.
Reviewed by Nathalie Brooks, Owner of Brooks Heating & Air and Treasurer, HRAI Contractors Division Board of Directors · Updated July 22, 2026
There are two practical ways to heat a backyard pool in Ontario: a natural-gas heater, which burns fuel to heat water quickly on demand, and a heat-pump pool heater, which pulls warmth from the summer air more slowly but at a fraction of the running cost. Gas suits short seasons and weekend-heat-it-up habits; a heat pump suits pools kept warm all season.
How does a gas pool heater work?
Pool water is pumped through a heat exchanger warmed by a natural-gas burner — the same principle as a gas furnace, applied to water. Gas heaters raise pool temperature fast (often 1–2°C per hour depending on pool size), work in any weather, and are the only realistic choice if you want a cold pool swim-ready by the weekend. The trade-off is fuel cost: they are the most expensive option to run continuously. In Ontario, gas pool heater installation is licensed gas work — the connection must be made by a TSSA-registered technician.
How does a heat-pump pool heater work?
It works like the cold-climate heat pumps we install for homes, in reverse season: it extracts heat from warm summer air and transfers it into pool water. Heating is slower, but efficiency is far higher — several units of heat per unit of electricity when the air is warm. It shines from June through August; performance drops in chilly shoulder-season air, exactly when a gas heater doesn't care.
Which pool heater fits which Ontario homeowner?
- Gas: occasional heating, early/late season swimming, hot tubs, fastest warm-up.
- Heat pump: pool kept at temperature all season, lowest operating cost, quieter monthly bills.
- Common mistake: under-sizing either type — an undersized heater runs constantly and never catches up on cool nights.
Next step: Deciding between the two for your pool? Get real numbers for your pool size and habits — request a pool heater quote or call (905) 877-3100 and ask for a pool-heating assessment.
Frequently asked questions
Can I run a heat-pump pool heater in May or September?
Yes, but output drops as air temperature falls — below roughly 10–15°C air temperature, a gas heater becomes the more practical choice.
Do I need a permit or licensed installer for a gas pool heater?
The gas connection must be made by a TSSA-registered gas technician in Ontario. Brooks Heating & Air is TSSA-registered.
How long does a pool heater last?
Gas heaters typically 8–12 years; heat-pump units 10–15 — water chemistry is the biggest factor for both.
What size pool heater do I need?
Sizing follows pool surface area, desired temperature rise, and whether you use a cover. A quick site visit gives an accurate answer.
Is solar pool heating worth it in Ontario?
Solar can supplement, but Ontario's season and sun angle mean most homeowners still pair it with gas or a heat pump for reliable temperature.
Related reading: What is a cold-climate heat pump? · Gas vs electric water heater comparison · Contact Brooks Heating & Air