Kromschroder Air/gas ratio control VAV125R/NWAK 88004706

Kromschroder VAV125R/NWAK air/gas ratio control, SKU 88004706, is a component for gas burners and boilers. It maintains a set proportion between combustion air and gas flow across the burner's firing range. It is installed in the gas train after safety valves and upstream of the burner, with impulse lines connected to the air side and gas pressure. The control compares air and gas pressures and adjusts gas flow to keep the mixture within stable combustion limits as the burner modulates. This item is from the Control category and is referenced by model VAV125R/NWAK.

Parts of this type are selected by gas family and supply pressure, burner output range, pressure drop through the gas train, and required ratio characteristic. When replacing, check that impulse lines are intact, correctly connected, and free of condensation or blockage. Confirm the spring preload or ratio setting is transferred from the old unit or set per burner manufacturer's instructions. After fitting, verify the gas/air ratio with a combustion analyser over the modulating range, including light-up and shutdown.

Items of this kind may fail due to blocked or leaking impulse lines, causing unstable combustion or burner shutdown. A faulty control may result in incorrect gas/air ratio, leading to flame lift, yellow tipping, or excessive CO. Check for condensation or blockage in impulse lines, and verify the control's response to pressure changes. If the control fails to adjust gas flow properly, it may need recalibration or replacement.