What is "outdoors"?

[randynavarro]

I have a propane-fired Cat. I furnace installed outside but under an open carport.

Mfg. label clearly states: "CATEGORY I FORCED AIR FURNACE FOR INDOOR INSTALLATION ONLY IN A BUILDING CONSTRUCTED ON-SITE."

This furnace install isn't sitting right with me but I can't figure out why.

What's the difference between this install and a unit mounted in an attic or a crawl space?

[Robert Jones]

The crawl and attic are somewhat more protected and in some cases conditioned. The carport offers a cover but no resistance to weather like wind driven rain. How did they protect the propane line/connection?

[Richard Moore]

I would think that winds blowing around the cabinet could cause positive or negative pressure at the burners depending on the wind direction. Whether the effects would be enough to cause serious adverse effects on combustion and/or drafting is something I don't know, but given strong enough wind, yeah, I could see that being an issue in a carport where it wouldn't be in an attic or crawl.

There's also the issue of whether the electrics and electronics are adequately weatherproof.

Ultimately, I don't consider a carport "indoors" and I'd have to go with whatever the label says.

[Nolan Kienitz]

Under the carport, but maybe enclosed in a closet? I've seen that many times. Portion of the closet is HVAC/water heater and another portion of the sectioned off closet is shovel and rake storage.

[Bill Kibbel]

I agree with Richard that a furnace in a carport is not "in a building". If questioned on my call, I wouldn't hesitate contacting the manufacturer for confirmation of my interpretation.