Williams Millivolt Thermostat

The Williams Millivolt Thermostat (Model P322016) offers reliable, manual temperature control for millivolt heating systems such as gas fireplaces, wall furnaces and free‐standing hearth units. Its simple, non-programmable design ensures straightforward operation—no batteries or power hookups required. Engineered for precise, on-off switching via a rugged bimetal sensor, it delivers stable comfort in any room.

Compact and easy to install, this thermostat mounts on any standard wall box and works seamlessly with thermocouple and thermopile valves. Its mercury-free construction provides safe, long-lasting performance without leveling concerns.

Key Features

• Mercury-free bimetal sensor for accurate, consistent switching
• Non-programmable, manual on/off temperature control
• Designed specifically for millivolt (750 mV) heating systems
• Works with both thermocouple and thermopile valves
• No batteries or external power needed
• Fits standard single-gang wall boxes for quick installation