The answer to 'system upgrade not heating' is that the most common causes are incorrect system sizing, faulty thermostat, or issues with the new heating components. Symptoms may include the system running but not producing enough heat, inconsistent heating, or the system shutting off prematurely. Solutions can range from adjusting the thermostat settings, cleaning or replacing air filters, to having a professional HVAC technician inspect and diagnose the specific issue.
For a new system upgrade, it's best to have a professional HVAC contractor handle the installation and initial setup to ensure the system is properly sized and configured for your home. Attempting DIY repairs on a new system could void the warranty and lead to more complex issues down the line. If the system is not providing adequate heating after the initial installation, it's recommended to contact the HVAC contractor who performed the upgrade.