Brushed and vacuumed burner tubes Inspected and vacuumed burner and surrounding area Checked electrical connections and safeties Checked gas pressure Performed combustion test Manifold pressure-2.203 in.w.c. Bled all zones of air. When bleeding the zones we found one of the boiler drains was leaking from the packing nut and valve stem. Tried to tighten the packing nut but the leak did not stop. Drained pressure from the system and removed the old boiler drain. Installed a new boiler drain valve and filled the system back up with water. Purged all zones of air again and started and tested the system. Unit is working properly. Boiler pressure when leaving was 18 psi