Checked hot water heater for 1st floor and second floor. Checked all water connections for leaks and rust. Checked the gas connections to ensure that there are no gas leaks. The electronic components for both systems are operating properly at this time. Both systems are operating properly at this time. Performed preventative maintenance for a crown boiler system model #Awi061snlt1psu, serial #Piplft000331063. This system is for the first floor only. Removed and cleaned carbon off of the flame sensor. Cleaned out the burners and burner box. The water pressure is at 12 psi. The limit is set for 180. The expansion tank is in good condition. I observed the system starting normally. The circulator pump is operating properly. Performed a combustion analysis test and got the following readings, o2 is at 13%, co is at 15 ppm and the system is operating at 84% efficiency. The system is operating properly at this time. Performed preventative maintenance for a crown boiler system model #Awi037