Came out to call for a system not heating well. Customer stated that the system is set at 70 and it’s 65 in the home. Customer is remodeling and has half of the systems coverage area open to the attic temperatures. In that area of the home it’s 48 degrees. The system is doing all it can to satisfy the temperature. The filter was also dirty and was hindering the airflow of the system. Changed out the customer supplied air filter. The system can’t regulate the temperature difference of almost 20 degrees in the remodeled part of the home. The system will most likely have to constantly run to keep this section of the home mildly warm. System is heating properly within manufactured specifications, but won’t reach set temperature do to the extremely low temperatures outside, and the home open to attic temperatures.