Kromschroder Air/gas ratio control VAG120R/NWAE 88000272

The Kromschroder VAG120R/NWAE (SKU 88000272) is an air/gas ratio control with a fast-acting solenoid valve, designed to maintain a constant 1:1 air/gas ratio in modulating and step-fired gas burners. It has a nominal diameter of 20 mm with Rp 3/4 connection thread, a maximum inlet pressure of 500 mbar, and operates at 230 V supply voltage. The valve opens in ≤0.5 seconds and closes in ≤1 second, is classified as Class A per EN 161, and features IP65 ingress protection, a position indicator, pressure test points, and an M20 cable gland. It is certified to EC, FM, and CSA standards, and is manufactured in Germany. This valve supports minimal NOx and CO emissions, gas savings of 5-10%, and extends burner life.

When selecting a replacement air/gas ratio control of this type, ensure the connection size (e.g., Rp 3/4) and thread type match the existing piping, and that the supply voltage (e.g., 230 V) is compatible with the burner control. The valve's function—whether fast-opening, slow-opening, or servo-regulated—must align with the burner's control logic. Also verify the maximum inlet pressure rating and the air/gas ratio range to suit the system's operating conditions. Check the pneumatic or electrical interface with the fan and burner control, and confirm the valve's classification (e.g., Class A) meets safety requirements.

Common failures in air/gas ratio controls include coil burnout, leaking seats due to debris, drifting outlet pressure, or a seized servo regulator. Symptoms on the equipment may include unstable flame, incomplete combustion, increased emissions, or failure to ignite. Check the coil for continuity, inspect the valve seat for debris, verify outlet pressure against air pressure, and ensure the servo mechanism moves freely. Also confirm that the gas pressure switch settings are correct after installation.