In my earlier notes I forgot to mention that the Platinum Cat heaters from
Thermal Systems are vented.  Other catalytic heaters on the market, as far
as I know, are not.  This makes a big difference.  If you forget to open a
window with an unvented heater condensation is a major problem.  The vented
catalytic heaters avoid this problem, as well as the obvious safety
problems involved with operating an unvented combusion heater in an
enclosed space.

Bill