De Dietrich 85185516 gas valve Sit SIGMA 840

The De Dietrich 85185516 gas valve is listed under the catalogue article 336.331.005 and manufacturer codes 85185516 and 336.331.005 in the gas valves category. It is a part of the Sit SIGMA 840 series. No further specifics about this particular valve, such as connection size, coil voltage, or function, are provided in the product data. Gas valves of this type shut off and meter the gas supply to the burner. They open on command from the burner control only when the gas pressure switch permits gas flow. In premix boilers, a pneumatic gas/air link ties the valve to the fan for correct mixture control. Such valves are selected by brand and series, connection size (typically Rp 1/2" to 2" or flanged), coil voltage (common values 230 V or 24 V AC/DC), and function – single or double solenoid, slow opening, servo-regulated, or multiblock versions that incorporate a filter and regulator. The coil is often replaceable separately from the valve body. When sourcing a replacement, typical failure modes to check include coil burnout (test winding resistance), leaking seat (check downstream pressure with valve closed), drifting outlet pressure, or a seized servo regulator. The valve interfaces with the burner control, gas pressure switch, and gas filter in the fuel train. Always verify the electrical supply and physical mounting dimensions against the existing installation before ordering, as these parameters are not standardised across all series.