Dennis wrote
Last spring, I posted a line of portable heaters that stayed outside and
used a 3" hose to pipe in the heat. I forgot what brand they were. I'll
look some more and repost when I find it.

Dennis  Are you talking about the ZODI heaters?   If so I have one and use
it to heat my westy.  I fabricated up a gutter mount for it with the air
coming into the slide window.  It heats really well.  No fumes, moisture,
or oxygen depletion, just warm air.

www.zodi.com

Regards
Graham