018" orifice for propane will result in over-firing and a dangerous pilot flame

Durable Construction: Engineered to withstand high-cycling environments within the furnace plenum for long-term reliability

Broad Compatibility: Fully compatible with McDonnell & Miller Series 53

this is a #20 orifice which is common in many York residential models

Marley Engineered Products 4520-2059-000 Limit Switch 018" orifice for propane willThe Marley Engineered Products 4520 2059 000 is an OEM 160 230F AUTO Limit Switch designed for high accuracy temperature monitoring in HVAC heating systems. This heavy duty bimetal disc control serves as a critical safety component, engineered to automatically interrupt the circuit when internal temperatures exceed the 230F threshold and reset once conditions return to the 160F range. Frequently utilized in QMark and Berko heaters, this 4520 2059 000