Boiler Anatomy 101

A boiler is a plumbing appliance that heats (and occasionally boils, though that’s not the purpose) water. It’s often confused with a furnace , which is for only high-temperature heating . This plumbing appliance uses wood, coal, oil, natural gas, or resistance heating elements to heat water . This is for various uses around your home, including cooking, showering, and central heating . Three different types of residential boilers are common. This list includes components of a combination boiler, system boiler, and regular boiler. However , each heating appliance has basic plumbing components that Warner Service outlines below.

Aquastats . Components used to sense the water’s temperature and tell the burner when to start and stop
Backflow valve . A safety device that allows water to flow in a single direction only
Burner. The area where air mixes with the boiler’s fuel source and combusts
Circulator Pumps. Components used to push hot water or steam from the system to the heat distributors
Expansion Tank. A small tank off the main boiler that helps protect the system from excessive pressure
Feedwater Drum. A component used to prevent water from being open to the atmosphere through its cycle; lies between the steam drum, main condenser, and deaerated feed tank
Firebox. Also known as a combustion chamber; the location where the system’s fuel meets air, creating a flame
Heat exchanger. A component used to carry heat from the burner to the water without direct contact with the water
Pressure Gauge. A component used to measure pressure inside the boiler
Refractory. Materials used to fill any gaps and/or openings around the firebox to ensure the fire stays in the firebox
Return Lines. Components used to bring cooled water or steam back to the boiler for reheating
Safety Valve. A component used to automatically open if the pressure within the boiler exceeds a certain threshold
Safety Shut-Off Valve. A component used to automatically shut off the fuel source during critical safety times
Steam Drum. A reservoir of water and steam at the top end of the water tubes that stores steam generated in the water tubes and acts as a phase-separator for the water and steam mixture
Superheater. An accessory to residential boilers; a component used to remove excess moisture from the steam by raising it above its saturation point to avoid turbine damage
Supply Lines. The pipes that deliver heated water or steam to the distribution points
Water Level Indicator. A component used to check the water level inside the boiler

It’s important to recognize that boiler parts divide into mountings and accessories, auxiliaries, and safety protections . Ask your preferred local plumbing technician for details about how the boiler benefits from a thorough inspection and regular boiler maintenance . To get a head start, download Warner Service’s Boiler Maintenance Checklist . We outline the basic steps for daily, weekly, monthly, and annual boiler maintenance. Click on the button below to download:

Note: As always, follow the boiler manufacturer's recommendations for optimal performance. Don't attempt any boiler maintenance if you're unclear of the directions. Call a plumbing professional for help .

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Boiler Anatomy 101