The 400-4 from Taco is a 1/8” NPT Hy-Vent Air Vent. This item is simple, easy to install and is compatible with any heating system. For best performance use it in combination with Taco Air Scoops that have a 1/8" outlet on top. The vents are easily serviceable by simply unscrewing the vent cap.

Technical Specifications:

• Inlet connection: 1/8" NPT Male Threaded;
• Max Venting Pressure: 50 psi;
• Max Operating Pressure: 150 psi;
• Max Operating Temperature: 240°F;