Damp smells from disused Chimney (Ed.)

[LJ94]

Hi folks

I recently bought and renovated an 1863 cottage. As part of the renovation what was used as the livingroom now serves as our bedroom. The property has 2 chimneys, one has been bricked up and plastered over with what appears to be a small vent on the external gable wall.

What was previously the livingroom (now our bedroom) had a gas fire which we have disconnected from gas and it is currently out of use. We had a builder round who has sealed the chimney at the top as the stack and pot were extremely damaged. We do intend to vent chimney both at bottom and top. At the moment we have a bag over the fireplace with some holes to allow some airflow as we believe chimney was leaking slightly so needed to dry out. The intention is to remove gas fire and plasterboard fire place including a vent for a more modern look
The issue now is that we are still getting draughts through the fireplace when its windy even though it has been sealed? Its also bringing in an unpleasant wet stone smell. We cant find where this air would be getting in as no vents in chimney stack or in loft space coming into fireplace.
Does anyone have any ideas about why we are still getting draughts other than builder not sealing it properly? We know that sealing a chimney isn't the best choice but we felt for a bedroom we were losing a lot of heat especially if we arent intending to use the fire and felt small vents would suffice to prevent moisture build up.

Thanks

 

[blup]

Even a small difference in air pressure can create draughts, the gas fire kept the flue relatively dry, now the damp/ ingress of rain etc have returned.

Blup

 

[LJ94]

Thanks. Yes we have thought it could be this and have been told chimney could take a while to dry. We hope that venting both ends will keep it relatively dry once its had a chance to dry out. Damp scottisj weather doesnt help much.

 

[LJ94]

We think the sooner we get the vent in place the better as warm air is obviously being sucked from bedroom potentially causing more moisture as it now has no where to go so we think with proper ventilation it could solve the issue with moisture. It was the draughts that confused me as the top is completely sealed so unsure how draft would be getting in or can brick let draughts through without necessary having a hole?