Honeywell VQ425BD1005-0300A gas valve DN25

This Honeywell VQ425BD1005-0300A gas valve is listed under catalogue article 534.322.157 and manufacturer code VQ425BD1005-0300A. It carries the designation DN25. Parts of this type are used to shut off and meter the gas supply to a burner. They open on command from the burner control and only when the gas pressure switch confirms sufficient pressure; in premix boilers a pneumatic gas/air link ties the valve to the fan. Selection of such valves is based on brand, series, connection size (Rp 1/2" to 2" or flanged), coil voltage (typically 230 V or 24 V AC/DC), and function – single or double solenoid, slow opening, servo-regulated, or multiblock with integrated filter and regulator. Common failures include coil burnout, leaking seat, drifting outlet pressure, or a seized servo regulator. The coil is often replaceable separately from the valve body. When replacing a gas valve, verify the voltage and connection size of the existing installation. This valve is designated DN25, so the piping and mating components must match that nominal bore. Always check that the valve’s function (e.g., single or double solenoid) corresponds to the burner control type and the safety sequence required by the appliance.