DIYbanter - open fire and condensation

Hi,

I'm looking for some advice, hope this is the right place ;O)

I have recently bought an old pre 1930's bungalow with nine inch solid brick
walls and an appalling condensation /mildew problem due mainly to the fact
that what with double glazing which has no vents or night latch,
draughtproofing and oil as the only heat source, the place is vacuum packed!

I understand from reading this group on deja that leaving my heating on 24-7
is the best
way to prevent the condensation but thats just not affordable in the long
run. At the moment
I am using 500 litres every six weeks or so and thats running it at 65
degrees in the evening only.

I have the place as well insulated as possible and even priced inner
insulation for the outer walls using a polyurethane
sheeting faced with plasterboard and that worked out at over £500 per wall!
Multiply that by ten walls and its
just insane!

Anyway...getting to my point.

I want to build on an external chimney and install an open solid fuel
(coal) fire with an all night burner which will keep it ticking over all
night.
What I am wondering is, will this help with the condensation
problem by giving the moist air an escape route, or will it make it worse?

Hope someone out there can help.

Thanks
Susan :O)