Just wanted to cover this earlier comment because it’s risky thinking:
What Mzip was referring to is called a half-wave rectifier. It doesn’t cut power in half, it actually reduces it to 40% or less. It also creates a 30hz wave which is a lot of ripple, and it creates an imbalanced AC line load. None of this is a good idea, aside from the obvious voided warranty issue.
Half-wave rectifier should only be used on lower power loads (say like, a third of what this printer heatbed is pulling).
The proposed code-only solution is not only going to perform better, it’s actually safe and keeps your warranty. Stick with code.