Not being efficient with my heater

My sister and her fiance purchased their starter home out near my mom and I couldn’t be happier for them. The house is quaint and is a typical country cottage. Just perfect for a young couple starting out. My sister and her future husband invited me over for dinner one night to thank me for all the help while they moved.  I was the only one in the family with a truck so we used it to move all the furniture and appliances. I walked in and I noticed it felt really chilly. Knowing they were trying to save money, I figured they kept their thermostat setting very low. I began to think that the thermostat setting must have been set in the low 50s as I was freezing.  When my sister mentioned that she was cold, it gave the opportunity to ask if there was a problem. She said that they were having a really hard time keeping warm and couldn’t figure out why.  I offered to check stuff out but pointed out a several things I already noticed. A few heating vents were blocked by furniture, shoes, and other things and I told her that it restricted the airflow.  That alone would make the system not work efficiently.  Then I noticed my sister hadn’t changed the air filter in her HVAC unit, which was also significantly restricting airflow into the system. The air filter was filled with pet hair, dirt, and who knows what.  It looked like it had been for quite a while. As they were new to home ownership, I suggested that they call an HVAC company to set up an appointment.  I told them that when the technician was there he could go over the system, change the filters, and even give them money saving tips on how to get the most out of the system.  It is always best to learn from a professional if you don’t know anything about things like heating and cooling.        

gas heater