Can you have unit on regular heat when temp is below 40 degrees outside?

Yes, you can run your heating unit when the temperature is below 40 degrees outside. In fact, many heating systems are designed to operate efficiently in colder temperatures. However, it's important to ensure that your unit is properly maintained and suitable for low-temperature operation to avoid any potential issues, such as decreased efficiency or freezing components. Always consult the manufacturer's guidelines for optimal performance in cold weather.