Tomes wrote:
If the flue is unusually cold and I really feel the cold downdraft,
I put a ceramic heater in the firebox for 30 - 40 minutes to warm it up.
Then I hold rolled up newspaper near the flue to get the updraft started.

Regards,

Harry

I have the same problem from time to time. I've found that if I turn
off my central heating system that it seems to help. I think when the
system is running it makes for just a slight vacuum in the house that
allows the air want to flow down the chimney. After the fire is going I
turn the system back on again and no problem.

-Richard