I’m in the south where ‘floor furnaces’ were very common forms of heat. They were always located in the front hall and the grills were minimum 24”x 36” and when on could burn your flesh. Worked fine for a century. It sounds like someone has suggested this location to you for a return vent. Can it work? Absolutely. Are there other options? Very likely. None of us can see your house. If you are not vibing with this installer call someone else.

Thank you!

I have a floor vent thats about that size, but, its off to the side, of a larger hallway, so is not where walking paths are. I dont think, I would want one in the path to a bathroom, especially, if someone is walking on it barefooted. They are not comfortable for that.

Thanks!

That is where our larger cold air return for a forced air HVAC system is. I have no idea if it's considered "safe" but we did replace the furnace and ducts about 10 years ago and more recently have had HVAC people out to look at it to see if we could feasibly move it to another area and they were all decidedly unconcerned by it. Ours is flush with the flooring and at some point someone gave it a hardwood grill to match the floors. My only real issue with it is that our kids are constantly dropping things into it (the hallway serves their bedroom and the bathroom). A mesh screen would address that if we ever get around to it. I will say that we didn't find many better places for it--more commonly they seem to be in dining rooms (and that is where we would have moved ours to), but I'm not sure that would be better. We decided to just leave it be and wait until we eventually upgrade the HVAC to a heat pump.

Thank you!