A leaky boiler drain will often be caused by a rusty drain and will require you to apply a rust inhibitor to stop the leak. There are certain tips you'll need to do this safely.
Tip 1 – Shut off Electrical Power
Most likely there will be water on the floor around your boiler, a very good conductor of electricity. Be sure to turn off your electrical power to your boiler.
Tip 2 – Examine the Draining Water for Rust
Drain water from the boiler, remove the drain valve, and examine the drain for any brown-colored rust. If rust is present, spray the drain with rust inhibitor.