Arrived onsite for maintenance for one gas fired boiler. Requested the customer turn on the thermostats up to heat and confirm operation of the boiler and each zone valve. Turned the boiler off and removed and cleaned all burners and wiped cleaner the burner compartment. Performed a visual inspection of all electrical and inspected all external water components such as the exp tank, fill valve, backflow preventer and the circulator pump. Completed combustion test. Observed over 20 psi of boiler water pressure. Reduced to about 18 pounds of pressure. Didn’t observe a swishing sound indicating water in the line but did hear slight knocking. Reducing the pressure may reduce the knocking sound. System is otherwise operating as it should.
