Hydronic Heating Systems – Drain-Tempering Valves Limit Discharge Temperatures
Challenge: Balboa High School in San Francisco, CA, required a boiler system upgrade to meet modern safety and plumbing code standards. The new low-pressure steam boilers needed to control maximum drain discharge temperatures while maintaining a safe environment for students and staff.
Solution: Guttmann & Blaevoet Consulting Engineers designed the project, with Tünde Munz, P.E., LEED AP and Principal of G&B, initiating the solution. As required by code, these low-pressure boilers must have relief valves. Due to safety concerns about venting steam near where students are congregating, the designer chose to vent the relief valves into suitably sized piping, which runs to a floor drain inside the boiler room.
To comply with plumbing codes limiting maximum drain discharge temperatures, the designer chose to add self-operating, thermostatic, drain-tempering valves that only inject cold water into the vent lines when the relief valves activate.
These drain-tempering valves from ThermOmegaTech automatically detect when the drain temperature is above allowable levels and discharge just enough water to temper drain flow below the allowable 140 degrees F.
Result: ThermOmegaTech’s drain-tempering valves provided a maintenance-free, energy-efficient, and code-compliant solution. The system operates reliably with minimal installation complexity, reducing both upfront costs and long-term maintenance needs.
