600 BTU/hr depending on manifold pressure—it provides the exact fuel-to-air ratio required for safe atmospheric burner operation

for the 1/2" MPT center branch

Robust construction designed to withstand repeated thermal cycling and manual strain on the control head

making it a staple for HVAC service kits and boiler repair applications across residential and commercial heating systems

provided the target outlet pressure falls within the 5-12" WC range

McDonnell & Miller 312200 Gasket 600 BTU/hr depending on manifoldMaintaining the integrity of boiler water feeders and liquid level controls requires high performance sealing components designed for steam and hydronic environments. The McDonnell & Miller 312200 Gasket is a critical replacement valve bracket gasket engineered specifically for Series 21, Series 25A, and Series 27 units, including the 27W model. As the direct updated version for 311100, this part ensures a precision fit for mechanical water feeder