A heater that won’t start can ruin a cool spring weekend, but some causes are simple to check. Others, especially anything involving gas, need a licensed professional. Here is how to tell the difference.
Safe checks you can do
- Is the pump running? Most heaters won’t fire without enough water flow.
- Is the filter clean? A dirty filter reduces flow and can trip the heater’s pressure switch. Check the filter pressure gauge.
- Are the baskets clear? Clogged skimmer or pump baskets restrict flow too.
- Is the heater turned on and set above the water temperature? Check the thermostat or controller, and any automation schedule.
- Is the gas supply on? Check that the gas valve to the heater is open and that other gas appliances are working.
- Is there an error code? Note it, and look it up in your owner’s manual.
Stop and call a professional if…
- You smell gas. Leave the area, do not operate switches, and contact your gas utility or emergency services.
- You see soot, scorch marks or melted components.
- The heater ignites and then shuts off repeatedly.
- You hear banging, rumbling or popping.
- Water is leaking from the heater cabinet.
Why gas work needs a licence
In Ontario, gas appliance installation and repair is regulated by the Technical Standards and Safety Authority (TSSA). Poolmaster has two TSSA-licensed gas technicians and is fully insured. They handle new heater installs, heater upgrades, and gas line troubleshooting and testing. See our gas work services.
Keeping your heater healthy
- Have the heater cleaned and checked at opening. Poolmaster’s Heater Clean & Light package covers basic cleaning, lighting and an operation check.
- Keep your water balanced. Unbalanced water can damage heat exchangers.
- Drain the heater completely at closing to prevent freeze damage.
Heater trouble? Request a quote or call 416-449-1450.


