HVAC system installers need to bore a large hole through the exterior wall of the house in order to pass refrigerant lines through to the compressor outside. Most take time to caulk the hole around the lines, but the caulk fails over time, often leaving a gap where air (and insects) can...
Or, given the same geographical and climatic situation, if two people in the house want to use hot water at the same time, those two users might have to share the hot water coming out of the water heater -- and neither is likely to be satisfied with how much they are getting. The k...