Central heating overflow valve - has flat annular sealing face on valve plate with peripheral radiused edge

摘要

The overflow valve with threaded inlet and outlet unions is for the bypass pipe between the hot-water feed and return pipes in a central-heating system. It has a valve plate with a stem guided axially in the housing, and spring-loaded shut by a compression spring acting between a housing shoulder and the plate, pressing the latter against a seat ring. The annular sealing face on the plate (8) is flat, and has a peripheral edge (9) with a radius of less than 0.5 mm. The ratio of the clear diameter (d) of the seat ring (4) to that (D) of the valve plate (8) is 1:1.6. The ratio of the inner cross-sectional area of the housing to the surface area of the plate is 1.83:1. ADVANTAGE - Simple to produce and install, and ensures constant residual delivery head over a set operating range.