Written on: May 18, 2016

AFUE and Your Boiler: Understanding Real-World Boiler Efficiency

AFUE (Annual Fuel Utilization Efficiency) is the most widely used measure of a boiler’s (or furnace’s) heating efficiency (you’ll see AFUE indicated on the yellow stickers on your boiler).

AFUE measures the amount of heat delivered to your house compared to the amount of fuel the boiler or furnace uses to produce it. A boiler that has an 80 percent AFUE rating converts 80 percent of the fuel it receives to supply heat — the other 20 percent is lost out of the chimney.

The problem, as we’ll see, is that boiler efficiency is about much more than AFUE: to understand boiler efficiency in the “real-world,” other factors need to be considered.

Real-world boiler efficiency

A study by Brookhaven National Labs showed that a homeowner could spend as much as $800 more per year on fuel with one boiler compared to another with a nearly identical AFUE rating.

Why does this happen? By definition AFUE only measures energy lost to the chimney –it does not take into account other significant inefficiencies, including:

• Jacket loss – Poor insulated boilers allow heat to escape constantly.
• Idle loss – Conventional boilers often run day and night to keep hot water available – even when no one is using it.
• Loss from draft regulators – Draft regulators (which control suck warm air out of your home to control chimney draft for the boiler – which means your boiler has to work to heat the cooler air left behind.
• Heating load mismatch – If your boiler is too large or too small for the heating load of your home, it will overwork and run less efficiently than its spec suggests.
• Inadequate maintenance – Any home comfort system will lose 5-10 percent or more of its performance every year without proper maintenance – not to mention that maintenance.

System 2000 – A different kind of boiler

Westmore features a unique boiler solution for your home – the Energy Kinetics System 2000®, which combines heat and hot water to maximize efficiency in all seasons.

The unique design of the System 2000 significantly reduces or eliminates chimney, jacket, idle, and draft regulator loss, cutting your bills by hundreds of dollars every year.

Plus, the System 2000 heats water up six times faster than most water heaters – which means no more cold showers!

A System 2000 boiler – properly sized, installed, and maintained by your Westmore technician – is an investment in your home comfort that will pay for your family for years to come.

Contact Westmore today for a FREE estimate on an upgrade to your home oil heating system!