Brushed and vacuumed flue pipe and heat exchanger Replaced oil filter, nozzle, and strainer Checked all electrical connections and safeties Performed combustion and smoke tests 5.8%o2 40 ppm co 0 smoke While performing the maintenance the customer stated the autofeed was leaking by and he needs to periodically check the boiler and add pressure. After getting customer authorization we drained some pressure from the boiler and removed the old autofeed. Installed a new autofeed and purged air out of all 3 zones. Started and tested the system. When leaving boiler pressure was at 20 psi. Unit is working properly.