Jude continues his look at different valve types. This time he shows how non-return valves (NRV) work and how they are used. NRVs are common in the boiler room so knowing what they are and how they work is very important. Weekly Boiler Tips are compiled by the knowledgeable and remarkably prolific content creators at WARE, a family owned, third-generation, 69-year-old commercial and industrial boiler rental and service firm based in Louisville KY. You can learn all about this and more at WARE's Boiler University.