Dan Holohan will present “Classic Hydronics,” April 9 at the Holiday Inn in Grantville, Pa.

All proceeds from this seminar will benefit the Oil & Energy Service Professionals’ Dave Nelsen scholarship program for students interested in pursuing careers in the energy-service industry.

The seminar will cover one-pipe loops; the critical importance of pressure differentials; gravity hot-water heating, pumping; radiation; one- and two-pipe primary-secondary systems; two-pipe direct and reverse returns; classic radiant; multiple-boiler systems; diverter Ts; two-temperature systems; air problems and other subjects.