The message
from David contains these words:

On Oct 1, 3:11*pm, jal wrote:
We have an open fire, which we use occasionally during the winter. * I
rather fancy opening up a vent in the floor, near the hearth, in order
to feed the fire with air from the vent, rather than it sucking draughts
in via the doors to the room.


Quite a timely thead for me this as we're having the living room floor
done and I was thinking that now would be the time to put such a vent
in. However, I have one doubt. I remember chatting to a damp
treatment bloke who told me that one of the problems with older
properties is that they get damp as they were (to paraphrase) meant to
be draughty and heated with coal fires. If I bring ventilation direct
to the woodburner, will I be depriving the house of a beneficial
airflow and exposing the house to the danger of damp/condensation?

Not sure what you mean by "having the living room floor done."

What sort of floor is it now?
What are you doing to it?
What's underneath it at the moment?

There's many a suspended wooden floor is sitting just a few inches above
damp bare earth.

If that's the case, and it's a wooden floor that's being repaired or
replaced with similar, then make sure that at the very least the bare
earth is covered with dpm which is well weighed down. And preferably
that there's a few inches of concrete laid on top of that. Plenty of
opportunity to put in an air feed for your fire then.

An underfloor draught to your fire will reduce the need for your fire to
take in combustion air from the room and so cause major draughts.

If you have an open fire, however, the "draw" (suction effect) of the
chimney will still take some of the air from the room up the chimeny and
ensure a significant amount of ventilation.

Keep a check on your relative humidity in the different rooms of the
house. Hygrometers are dirt cheap -- if you don't want to buy a proper
one, Lidl seem to be forever offering clocks with built-in hygrometers
for three or four pounds. If your Relative Humidity is higher than 80%
your house is far too damp. Should be in the region of 30% to 60%. Get
a decent dehumidifier if it's over 70% . I prefer to have models with a
built-in heater to ensure they work efficiently.