Boiler Maintenance and Repair- Performed preventative maintenance on boiler 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 While performing the maintenance we found 2 hi-vents that had corrosion on them as well as some corrosion on the top of the expansion tank. Also found the system has no autofeed and backflow preventer. Found 2 valves on the return have packing nuts that are very corroded and might start to leak if closed. Recommend replacing the hi-vents, expansion tank, and return valves. Recommend installing autofeed and backflow preventer so water can be easily added to the system.