The answer to 'why is my humidifier not heating' is that the heating element in the humidifier may be malfunctioning or not receiving power. This can happen due to a variety of reasons, such as a faulty thermostat, a tripped circuit breaker, or a problem with the wiring.
Some common symptoms of a humidifier not heating include low or no water vapor output, the humidifier not turning on, or the humidifier running but not producing any heat. To troubleshoot the issue, you can check the power supply, the thermostat settings, and the heating element itself. If the problem persists, it's best to call a professional HVAC technician to diagnose and repair the issue.