what would be the best type surge protector for new wall mounted boiler that can be put on a 4 square box? or mounted near a 4 square box?where can it be found?
That would be a type 3 SPD, those I have seen are plug in types. But you could use a wired type, type 2, but it will cost more. if your boiler can use a plug and cord, put in a duplex receptacle, and then a plug in type SPD, lots of those available