Kevin was at my house last week for annual heater service check and made necessary adjustments, which he explained to me. After he left I noticed a change in the heat throughout my house and called Interstate back again and asked to have Kevin stop by and talk to me about it. He explained what he had accomplished while here and why it impacted the heat in my house. He checked temps coming from different vent locations in the house and explained why temps would be different. So very knowledgeable and personable.