The answer to 'my furnace keeps shutting off' is that there are several common causes, including a dirty air filter, a malfunctioning thermostat, or an issue with the furnace itself. The furnace may be shutting off due to overheating, a safety feature to prevent damage. Symptoms can include the furnace running intermittently, not providing enough heat, or shutting off abruptly.
Some simple troubleshooting steps you can try are replacing the air filter, checking the thermostat settings, and ensuring the furnace vents are not blocked. However, if the issue persists or you're unsure of the cause, it's best to call in a professional HVAC technician to diagnose and repair the problem.