This specific part is engineered for horizontal mounting

and PFG series

meeting the original factory specifications for system safety and operational reliability in commercial and residential hydronic applications

allowing technicians to effectively conceal holes

as it compromises the factory-sealed terminals and can lead to voltage loss or improper spark timing

Johnson Controls T-4000-3139 Plastic Cover This specific part is engineeredThe Johnson Controls T 4000 3139 is a professional grade horizontal pneumatic thermostat cover designed specifically for the T 4000 Series room thermostats. Engineered for demanding commercial environments, this white plastic cover provides a clean, uniform look for horizontal mounted controllers where a blank faceplate cover is required. As a genuine Johnson Controls replacement part, it ensures a precise fit for single or dual element sensing units