How to Improve Boiler Combustion Efficiency

What You'll Need
Oxygen Trim Unit
Name and number of your HVAC technician
Flue gas analyzer

What is boiler combustion efficiency? Combustion efficiency refers to a measurement of how well heat of the fuel in the boiler transfers and becomes a usable heat. Combustion efficiency can be measured by checking the stack temperature. It can also be measured by determining the flue gas oxygen concentration. There are several things you can do to improve the boiler combustion efficiency. Follow the below how-to guide and you will see a marked improvement.

Step 1 - Understand the Operation at Maximum of Excess Air

In order to minimize the amount of heat loss that happens in your boiler, you can keep the boiler at maximum excess air. This will also help to improve the combustion efficiency of the unit. When you add excess air to your boiler, you actually improve the combustion. It is helpful to note that combustion is never completely efficient in the unit, and in fact tends to be more inefficient than efficient.

Step 2 - Analyze the Boiler Air Flow

In order to figure out how much extra air you need to add, you need to analyze the gas oxygen or carbon dioxide concentration that outputs from the flue. Consult with an HVAC technician to measure this properly. Have them test the stack readings. This will help you determine the flue's performance.

Step 3 - Tune the Boiler

Once you have noted the performance level, have your technician tune the boiler to adjust how it operates and improve the combustion efficiency.

Other Useful Notes for Boiler Combustion Efficiency

  • When you are looking for a generic reading about the gases produced in your boiler, you can purchase a flue gas analyzer. This analyzer can be bought at your local home improvement center or at a heating and air conditioning supply store. You will use this unit to measure how much oxygen concentration is in the flue gas. The units generally can be purchased for less than $500. A more expensive unit ($500 to $1000) is usually a hand held and computer based component. It will digitally display the percentage of oxygen and the temperature present in the stack gas. It will also measure the boiler efficiency. Several studies show that for a relatively low investment, you can save 30 to 50% more on your annual fuel costs by carefully monitoring the boiler efficiency.
  • Oxygen Trim System can be added to your boiler in order to control the combustion air. It automatically tunes the unit so that the air-to-fuel ratio is optimized according to your type of boiler unit. In order to add an oxygen trim system, you should consult with a certified HVAC specialist and have them install the unit. This is not a task that should be taken on by a do it yourselfer.