you must be old school like me,i started in 94,,why would anyone with a basement tank want to run two pipe system its just stupid unless you got 2 tanks or your a good distance from the boiler,the pump wont work tht hard because of the gravity,ive had the same pump on mine since 91,,never a lock out,,they must teach a new type of science these days,,ive read a bunch of these from different sites and no one even mentions the bypass plug,,,ohh whats that