Air Brick for Chimney

[robsartain]

We have a terrace house where there are two chimneys joining into one a the top. The two chimneys feed a downstairs room and an upstairs bedroom.

We have removed all fires and I planned to block the fireplaces in the upstairs bedrooms.

The question is can I get away with not having an air brick when blocking the upstairs off if I leave the downstairs fire places open ? I believe the idea for the air flow is so it drys out the chimney.

If I do have to have an air brick of some description does anyone know where I can get a nicely styled one, rather than the plastic vents ?

Thanks
Rob

[Road2Ruin]

The chimneys will not be combined, despite the fact that they look like they do. What usually happens is that they run next to each other then at the top the will have their own pot.

[robsartain]

Ok, they makes sense. You are right, from memory there is 2 pots. Will double check tonight.

So I assume each chimney needs somewhere for the air to flow, so if I leave the bottom of the chimney open and block the room above off (without an air brick) this should be fine ???

[Road2Ruin]

From memory I think you are ok if you seal the chimney at the bottom, ie the fireplace as the wind accross the pot will supply some movement, but not if you seal it at the top as no airflow from the bottom. However dont quote me on that.

[GreenV8S]

robsartain said:

We have a terrace house where there are two chimneys joining into one a the top. The two chimneys feed a downstairs room and an upstairs bedroom.

Do you mean there are four fireplaces in total, with each chimney serving a downstairs fireplace and an upstairs fireplace? I'm no expert, but that sounds extremely dodgy to me since there's a very good chance of fumes from downstairs coming out upstairs. Are you certain that's how they're arranged? I think you will need to provide ventilation for each separate flue pipe, but to do that you need to be clear how many separate pipes there are.

[mrmaggit]

You can block off the chimneys at the base if you wish, but you should install some form of ventilation at the chimney pot. By far the simplest method is to put either a fluvent or mushroom vent in the top of the chimney pot. Do not use a hood pot unless you want to be removing dozy birds that fall down the chimney. Far easier than removing the pot, and buiding in an airbrick or two. If you don't provide ventilation at the top, damp will come through the wall from the chimney.

[mrmaggit]

You can block off the chimneys at the base if you wish, but you should install some form of ventilation at the chimney pot. By far the simplest method is to put either a fluvent or mushroom vent in the top of the chimney pot. Do not use a hood pot unless you want to be removing dozy birds that fall down the chimney. Far easier than removing the pot, and buiding in an airbrick or two. If you don't provide ventilation at the top, damp will come through the wall from the chimney.