I found with a search Empire Propane room heaters that can operate without electricity and appear to have vents that can vent vertically through a pipe and presumably out through the roof. I'm sure there are others. .

Yeah, I've been looking at stuff like that for hours. The only ones that actually fit the wall I need to put them on are all ventless. The vented ones are all much larger--in size and BTUs-- and won't fit the space at all, leaving me with only one very poor option esthetically and in the main living area for a vented one.

I don't consider HVAC equipment to be anything other than functional - they rarely offer aesthetic highlights in any way. The aesthetic of any free standing heater appliance is the heat it provides.

If you want aesthetics, there are a number of wall mounted "radiators" that are quite artistic and design-positive. Or, you could use simple panels or baseboards. A hot water system can function, if a bit slowly at first, without a pump with enough of a height difference between the "boiler" and the radiators so that the water circulates by convection - hot water rises, colder water falls. I lived in a place with such a system, there was a one story difference between the boiler and the first floor of living space. A basement would work.

If you put in a normal atmospherically vented gas tank water heater, you'll have a heat system with only pipes in walls and floors that will work when the power is off.

No basement, Fudd, only crawl space. Mini splits for main heat source. Tankless (Rinnai) for hot water. Very small house, one story, though not tiny house, so very little free wall space. All other options have been considered. Only other option appears to be larger than needed propane "fireplace" type stove in front of a crucial window with stove pipe running up in front of window--all models larger than I need both in size and BTUs. I'm exceedingly unhappy with this option, but unless a small, on wall vented propane heater exists, I'm stuck with that.

Certainly no space for a fireplace, Cretin. except that too large gas one.

Is there no one who can address my original question?

If you're 'building something new, can't the layout or plan be altered to accommodate what you want?

No, not without making it a much larger house.

Well, if you have zero flexibility, then it's your decisions that limit your choices. Good luck.

Just found a Williams Direct vent wall furnace that looks like it might work. It would have to go, unfortunately, in the living room in order to direct vent to the outside. But I think I could hide it behind furniture; I could move the furniture during the rare periods when it's needed. And it works when the power is out, which many apparently do not.

I wish when you googled something, you didn't get a million things that absolutely do NOT fit what you googled. Huge waste of time and energy.

Be careful about "hiding" a heater behind furniture, they depend on air flow to work.

I'm not sure why you need to get your own info. Can't your contractor help you?

I reccomend you "interview" propane suppliers in your area. They will not only compete for your future business,they will suggest solutions. Where I live,code doesn't require space heaters to be vented and a large number of unvented heaters are in use. In the pasted 50 years the ONLY time I heard of a problem turned out to be because air - fuel mixture was grossly out of adjustment. Don't overlook the possability of a small generator or standby solar power to supply limited service during power outage. Having standby power capiable of running whole house as usual is a luxury,you can make do on far less. If you opt for a generator,power it with propane. Gasoline is a pita because you must periodically dump fuel,fill with fresh fuel and run it. Propane can stand unused for months then start and run as well as if had been in constant use. The 250 gallon tank at our hunting and fishing camp has 9 year old propane in it and everything including genny and propane fueled atv start's and works fine.

Thanks for the comments. Cost is a factor in the building of this small house and with material costs skyrocketing, a generator is completely out of budget range.

And though the heater I'm looking at will be hidden by furniture most of the time, obviously, as I previously stated, I will move the furniture away during the rare periods when it has to be used. I'm not an idiot.

The only propane supplier I would trust, the one I use now, carries only Rinnais and Rinnai does not make a heater that will operate without power. They will install the Rinnai water heater in the new house.