ITT Hoffman Specialty 401437 75H Non-Vacuum Air Valve - Industrial HVAC System Component for Airflow Control in Commercial Buildings

Bought this Hoffman specifically because of reputation. This is generally the most important value in the system. It sticks open, no heat (well the system has to work twice as hard) it sticks closed you could blow a pipe. It's also buried in the system and unless your looking for a problem you won't see it. So the plumbers choice from home Depot aren't a good idea, you want something that's going to outlast you.