At the following address:
http://www.netins.net/showcase/solarcatalog/catalogue10.html
I found vented Platinum Cat Catalytic Radiant Propane Heaters
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    The Platinum Cat operates on economical, clean burning and
convent natural gas or propane which is the least expensive form of
energy available. They come with a 12VDC or 110VAC operating exhaust
fan and controlled circuitry with a remote thermostat.  This heater
uses the unique and very efficient catalytic combustion process which
produces sun-like radiant heat with many safety features built in.
They are vented through a 1.5 inch plastic pipe through your crawl
space or basement to an outside wall.
     Therefore they do not have to be mounted on an outside wall.

     We have a small one in our bath and another one in my office. We
are very pleased with them as we heat only the areas that we are in
and do not have to waste energy.

Model      BTU/H  Power   Price    User Friendly Price  Size in inches
LP/NG-5.6  5.6    115VAC  $536.00  $400.00              28x12.5x5.5
LP-5.2     5.2     12VDC  $414.00  $315.00              21x12x5.5
LP-3.0     3       12VDC  $398.00  $300.00              14x12x5.5
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These are lower price than I recall seeing before.

Hope this helps someone else,
John