Derek Santangelo, Installation & power writer

Most of the returns I read about in reviews start with a number nobody checked. The cut-out was an inch too shallow. The plug-in insert turned out to want a dedicated 20-amp circuit. The heater was sold as warming 1,000 square feet and barely took the chill off one room.

So that's where I spend my time: the installation and electrical pages of the manual, the framing diagrams, and the fine print under the heater rating. I line up the cut-out width, height and depth of every insert in a ranking, note which ones ship with a plug and which are hardwire-only, and set what the listing promises about heat next to what the manual actually says.

I write the guides on power requirements, recessed installation and what a 1,500 W heater can cover. I'm not an electrician and I don't pretend to be one. When a job needs a licensed electrician or a permit, the guide tells you before you buy, not after.

Heat output is where I'm most stubborn. A square-footage claim with no wattage behind it doesn't count for much with me.