Smithville Furnace repair Upon my arrival I performed a 6 month checkup on 1 straight electric system. Flushed and treated the water removal system, replaced the air filter, checked systems safeties then verified system safety and performance. I found that the heat transfer media coil and the air circulation system have become dirty due to a restricted air filter allowing dirt and hair to pass through on the outside. All other operations for the system are performing to manufacture specifications. I spoke with the customer about my concerns and he would like the options emailed over to have the system cleaned and brought back to manufacture specifications. Once cleaning have been performed I advise to use a merv 11 filter and the system is able to move up from a 1” filter to a 2” filter