For contractors and technicians

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

System Safety: Crucial for maintaining the air-fuel ratio by preventing unmetered air from entering the combustion chamber

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

McDonnell & Miller 312200 Gasket For contractors and techniciansMaintaining 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