Performed preventative maintenance for a burnham boiler system model #ALP150B, serial #65605637. Homeowner also has an indirect water tank. Powered the system down and removed the access panel. Removed and cleaned carbon off of the flame sensor, cleaned out the burner box. The water pressure is within normal range and the limit is set for 180°f. Cleaned out the drain at the bottom of the heat exchanger. I inspected all copper piping for leaks. Checked all electrical connections to ensure that they are secure and in good condition. I powered the system up and called for heat. Took a combustion analysis test and received the following readings, o2 is at 13% and the co levels are 10ppm. All 3 zone heads are operating properly as well as the taco zone control box. Inspected each ball valve for leaks. The circulator pump is operating properly. The boiler is operating properly at this time.