McDonnell & Miller 302600 Head Gasket while the side ports are

while the side ports are standard 1/4" SAE flare

blocked return ducts

a compromised blower assembly gasket can lead to air leaks that destabilize the fuel-to-air ratio

Frequent cycling is typically caused by restricted airflow

McDonnell & Miller 302600 Head Gasket while the side ports areThe McDonnell & Miller 302600 Head Gasket, also identified by model number CO 12, is a critical 4 hole sealing component designed for low water cut off (LWCO) maintenance and float head repairs. Engineered specifically for high pressure steam and hydronic applications, this gasket provides a high integrity seal between the float chamber and the float head assembly. It is the primary replacement seal for a wide range of industry standard controls,