Combustion Efficiency

Definition:  A measure of how well your boiler is converting heat from burned fuel into usable heat.

Normal Operating Range* Atmospheric Boiler: 80% to 85%

Power Boiler: 82% to 90%

High Efficiency Boiler: 88% to 98%

:  Lower efficiencies leads to higher fuel bills

Solution:  Combustion efficiency as a standalone measurement is not useful for determining what repair needs or tuning requirements are required. Additional measurements from this report should give more incite as to what aspect(s) requires further attention.


Carbon Monoxide (CO)

Definition:  Deadly gas emissions that are produced as a result of improper combustion of fuel.

Normal Operating Range Stack Measurement: 0 to 100 PPM

Ambient Measurement: 0 to 25 PPM

:  Prolonged exposure to CO can cause severe health implications such as dizziness, nausea, vomiting and ultimately, death. CO is undetectable by site or smell.

Solution:  Most common causes are insufficient draft flow or an improperly tuned burner. It is imperative that a qualified licensed technician, with properly certified CO monitors, services your boiler.


Stack Temperature

Definition:  Temperature of the flue gases inside the stack or breeching. The goal of an efficient boiler system is to transfer as much heat as possible from the burner flame to the boiler’s heat exchanger. As the heat is “used” by the boiler, there is less heat to get exhausted through the stack and chimney.

Normal Operating Range Atmospheric & Power Boilers: 300 to 500 degrees.

High Efficiency Boilers: 100 to 200 degrees

:  Inefficient boilers do a poor job of transferring heat thus resulting in huge heat loss through the stack and chimney. This inefficiency is reflected in high stack temperature measurements and high fuel bills.

Solution:  Clean / Vacuum boiler fireside passages. Tune burner to proper specs.


Draft Reading

Definition:  Draft is the natural suction of the flue gases from the boiler through the breeching and chimney, ultimately discharging safely outside. Some systems use a mechanical fan to “push” the flue gases out of the boiler and through the chimney. Mechanical draft systems requires a special type of venting approved for positive pressure.

Normal Operating Range Natural Draft: .02 to .08” water column

Mechanical Draft: (see boiler specs)

:  Insufficient draft could lead to flue gases “spilling” into the boiler room such as carbon monoxide.  Burner flame will produce smoke and/or carbon monoxide.  Acidic condensate formed inside the chimney will destroy the chimney and liner.  Excessive draft can lead to decreased efficiency.

Solution:  Insufficient draft: Repair defective chimney. Make sure building does not have exhaust fans installed that may be interfering with boiler’s draft rate.  Excessive draft: Install barometric damper with CO spill switch.


Smoke (Soot) Reading

Definition: Unburned carbon caused by incomplete combustion.

Normal Operating Range 0 to 1 Smoke from Smoke Test

: Smoke or soot will coat boiler’s heat exchange surfaces which will lead to decreased efficiency or premature heat exchanger failure. Exposure to soot may cause long-term health problems.

Solution: Clean / Vacuum boiler passages and heat exchanger surfaces. Tune boiler for clean, safe combustion.

*Normal Operating Range is a basic average of all boiler systems. Your boiler and burner specifications will give more accurate ranges for your specific system.