In article oups.com,
(JMartin) says...

Gas logs are designed for aethestic purposes only. They are not designed
for heating and are very inefficient at doing so.

The one my mom has is a completely enclosed glass front unit with a heat
exchanger and air circulating fan. It is not too bad for efficiency,
heating by both radiation and hot air. Of course, when the power goes
out its efficiency drops way off, but it will still radiate enough heat
to warm someone sitting in front of it.

I'm a real fan of 19th century technology. This got me to thinking
about wing back chairs, which were designed to keep you warm facing a
fireplace. I don't know anybody who owns one any more.

When I was in college, one place I rented had a gas heater that heated a
vertical gas grill about a foot high and 18" wide. There were heat
exchanger fins above that. The grill would glow bright red and put out
a lot of heat, and the heat exchanger would scavenge what was left over.
I have never seen anything like it since. It put out as much heat as a
wood stove.

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