This is frustrating, but let's run through the checklist. First, you need to confirm power to the entire system.
- Go to your circuit breaker box. Find the breaker for your heating system and make sure it's on. Flip it off and back on to reset it.
- Locate the power switch on your furnace or air handler (often a light switch on the side of the unit). Make sure it's flipped to the ON position.
- Check that the furnace door or access panel is completely closed. A loose door can trigger a safety switch that shuts down power.
- Wait five minutes. Some systems have a built-in delay to protect the equipment.
If that didn't work, the issue might be at the thermostat wiring. Double-check that the wire from the wall's W terminal is firmly inserted into the W terminal on the T9's wall plate. Gently tug on it to ensure it's secure. If you have a heat pump, verify there is NOT a wire attached to the W terminal on the wall plate, as that can cause conflicts.
If the heat still won't fire, the problem could be with the furnace itself or a misidentified wire during installation. It's best to contact a professional technician at that stage.