hundreds, but close. They involved heaters manufactured between 2000 and
2007. It involved a gasket replacement and gas pressure adjustment. That number represents a small portion of the total number of heaters out there. They are sealed combustion, direct vent units. You might thinking of unvented units. I don't like installing them. I try to discourage people from installing them.
Maybe I'm missing something, but I don't see multiple gas or oil units being smart. It's one 280 sqft room. Just get one that's sized to heat the room from being cold when unoccupied to 65F in a reasonable time, say 30 mins to an hour? With electric, being easier to install, no service, cheap, etc, then I could see using multiple units, primarily if it's desirable to heat the whole space more evenly. But for a shop, maybe all he really cares about, at least for quick heat up, is one area around a workbench, etc. In which case one electric could be fine.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.