Furnace not heating: what to record and when to leave

Start with safety

Gas odour, a hissing gas sound, a carbon monoxide alarm, smoke or immediate danger takes priority over troubleshooting. Leave the building and call for help from outside. Do not use a phone, switch or appliance inside when you suspect a gas leak.

If there is no gas or CO warning, consider whether everyone can stay warm safely while waiting for service. Never use an oven, barbecue or outdoor fuel-burning heater to heat the home.

Make the request useful

Tell the contractor whether the furnace is silent, starts but stops, produces cool airflow or heats only part of the home. Record a visible thermostat message without opening equipment. Include when the fault began and whether there was a recent service visit or power interruption.

If you already have a written diagnosis, share it. Do not guess at a failed part or repeatedly reset equipment to keep it running. A qualified technician should explain the fault and the proposed repair.

Confirm the next step

Ask whether the appointment is for diagnosis, whether travel and after-hours charges apply, and when attendance is actually confirmed. A submitted online request is not an emergency dispatch or a booked appointment.