dpb wrote:
JRStern wrote:
...

Can't someone just screw on a piece of sheet metal or something?
...

Yes, that's what they were concerned about.

Absolutely not. You're talking letting combustion gas products into
the living space here--CO poisoning, iow. Life or death matter, not
simply a few bucks.

Many of us grew up in homes with gas space heaters with no lingering
effects.

Look! A squirrel!

If one is worried about it, a CO detector is far cheaper than a squirrel.