JG Underfloor Heating Manual Air Vent uses a thumb turn bleed valve to manually vent air from within the UFH system to eliminate any cold spots within a floor. The valve is easy to install as it simply screws directly into the manifold end connection on the manifold flow bar. Thumb turn bleed valve Manually air vent Thumb turn valve Durable DZR brass with a nickel plate finish Suitable for underfloor heating applications only