On Thu, 29 Oct 2009 23:39:21 GMT, Harry Bloomfield wrote:

They need good ventilation and yes they do produce lots of vapour.

Each kg of gas burnt produces a kg of water. But a kg of gas yields
quite a bit of energy. 10kW springs or there abouts springs to mind
so a fire running at a couple of kWhr output isn't a great generator
of moisture, a cup full/hour ish.

Probably best to use a fan heater if possible?

Yes. Not much difference in price of fuel and you do not need good
ventilation to use a fan heater - much safer.

Fan heaters don't work during a power cut... That is why we have a
portable gas fire.

--
Cheers
Dave.