Harald 90 westy said:

> I found that a unvented catalytic heater can
> give me a terrible headache if it stays on all night, even with a
> window partly open.

This may be so, but the heaters that I have used (81 gas & 85
diesel), I only used for a few minutes in the morning to take the
chill off while I/we dress.  A sleeping partner and a good sleeping
bag and a stocking cap are enough for the night.   So for my usage
pattern,  I think that for just a few minutes use (even 30), an
unvented heater would work just fine for me.

 Malcolm S