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 a small amount of water and rust inside the oil filter canister. Recommend getting oil sludge additive to remove any water and sludge buildup. Customer has a space guard 2200 air filter and wants one for ac maintenance