Tuning-Up New Heating Systems by Harris Hyman, P.E. When I bought a new truck, the salesman was careful to invite me to bring it back in after I'd put 1,000 miles on it. At that time, the shop changed the oil, tightened down the head, fixed a couple of rattles, straightened a door hinge, and greased the tailgate. I paid for the oil and filter, but the rest of it—maybe two hours of work—was absorbed by the dealer as a normal part of doing business. Last year, I designed a heating system for a school. It cost about ten times the amount of the truck. With typical perversity, the owner expected this extremely complex system to function perfectly from