Boiler Combustion Efficiency | HVAC Heating SystemsBoiler Combustion Efficiency | HVAC Heating Systems - It is important to understand that a commercial application (can also apply to residential boiler applications) is going to consume a large amount of the energy budget, therefore it is important to track efficiency ratings because a slight drop in the efficiency can cause a sharp increase in the energy costs.

Boiler Combustion Efficiency | HVAC Heating Systems

Understanding that, we all know it is important to have good preventive maintenance practices and regular system tune-ups including preventive maintenance practices. If you are tracking combustion efficiency it is important to keep accurate logs to track the data. When we talk about efficiency we talk about two related types of efficiencies and both can have an impact on the energy budget. There is efficiency and there is combustion efficiency. A decrease in combustion efficiency will decrease efficiency but not necessarily vice versa.

  • Combustion Efficiency is measured by dividing the usable heat produced by the fuel input in BTU/h content. This calculation is based on the actual heat available produced by the system after heat loss up the stack and other heat losses which do not provide usable heat. Excess air is partially responsible for the heat loss but it is necessary to complete the combustion process. Therefore it is important that the burner system is tuned and monitored on a regular basis. Using combustion analyzers the O2 and boiler stack temperatures can be monitored for spikes which will alarm the boiler maintenance crew about possible problems. It is important to maintain good combustion efficiency for overall efficiency.
  • Efficiency is measured by dividing combustion losses, radiant heat losses from the jacket and near boiler piping, and unknown losses (losses from tube scaling, soot build-up (exchanger thermal efficiencies)) by total fuel input in BTU/h. Much of the efficiency is determined by combustion efficiency and a lot of maintenance departments focus on combustion efficiencies and ignore the other heat losses.
  • Thermal Efficiency is related to how efficient the heat exchanger is working. Things like soot build-up or water scaling can reduce efficiency.
  • Steady-State Efficiency is the efficiency of running full blast under maximum load.
  • Overall Seasonal Efficiency is important to track to see if there is an annual degradation of efficiency. It gives you the big picture from year to year for comparison of efficiency.

Boiler Combustion Efficiency | HVAC Heating Systems | Conclusion

To get the most out of your system it is necessary to implement a complete maintenance/efficiency plan to maintain every aspect of efficiency. Providing that a maintenance/efficiency plan is put in place and qualified technicians perform the tuning with the appropriate tools, cost savings in energy use can be realized.

Don’t forget savings that can be realized by insulating piping and keep heat from going up the flue when the boiler is off. Little things like this will add efficiency and will pay for themselves in little time. For more ideas on this see our boiler efficiency options page.

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Boiler Combustion Efficiency | HVAC Heating Systems