15 ways to increase boiler efficiency：
1. increase boiler efficiency: lower the stack temperature
2. install an economizer
3. tune the burner regularly
4. install a variable frequency drive
5. increase boiler efficiency: insulate your valves
6. clean the fireside
7. preheat combustion air
8. clean the water side
9. return condensate to the boiler
10. recover heat from boiler blowdown
11. control blowdown rate
12. reduce excess air
13. reduce carry-over
14. survey steam traps
15. reduce steam usage
