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 cleaned all burners. Cleaned electrical 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. Confirmed everything is operating and heating properly at this time.