De Dietrich 85188921 ignition burner 3-7-10 sections

This is a De Dietrich 85188921 ignition burner, listed in the catalogue under pilot burners. The part number and the additional code 336.205.003 identify the item. The name indicates it is intended for use with boiler sections numbering 3, 7, or 10, though the exact meaning of these section counts depends on the specific appliance series. A pilot burner of this type serves as a small, dedicated burner that maintains a permanent or intermittent flame. This flame is used to reliably light the main burner and, in many gas-fired systems, also provides the flame signal through an integrated ionisation electrode. The pilot burner is typically mounted near the main burner and is supplied with a small gas flow via a separate line from the gas valve. Its flame is positioned so it crosses the spark gap from the ignition electrode and also contacts the ionisation electrode for flame proving. When replacing a pilot burner, the critical dimensions are the flame tube length, the mounting flange pattern, and the gas orifice size. These must match the original burner series, as the flame shape and position are precisely set for the combustion head geometry. Common failures include a blocked gas orifice from debris, a cracked ceramic flame tube, or a bent flame tube that misdirects the flame away from the spark or the main burner. Always check that the pilot gas filter is clean when fitting a replacement, and confirm the pilot flame appearance after commissioning – a stable, crisp blue flame that fully covers the ionisation rod is required for reliable lockout-free operation.