Boiler Parts Names and Functions — Complete Guide
Published: July 22, 2026 — CANRO Heating & Cooling — Greater Vancouver, BC
Main Boiler Components
Heat exchanger: transfers heat from combustion to water. Burner: where gas burns. Ignitor: lights the burner. Gas valve: controls gas flow. Circulation pump: moves hot water through the system. Expansion tank: absorbs water expansion pressure. Pressure relief valve: safety device that opens if pressure is too high.
Control and Zone Components
Control board: manages boiler operation. Aquastat: controls water temperature. Zone valves: direct water to different heating zones. Thermostat: tells the boiler when to run. Outdoor sensor: measures outdoor temperature for weather compensation. Flow switch: detects water flow. Temperature sensors (thermistors): monitor water temperature.
System Components
Radiators: emit heat into rooms. Baseboard heaters: emit heat along walls. Underfloor tubing: radiant floor heating. Pipes: carry hot water throughout the system. Air vents: remove air from the system. Filling loop: adds water to pressurize the system. Magnetic filter: captures sludge and debris. Condensate drain: carries acidic condensate away.