Chimney breast construction question

whizbang

I want to run an external air vent duct down to the fireplace, through the large void on the left side. Unfortunately it is blocked a few feet from the top with what seems mostly mortar, but possibly solid block in places. There is a small void on the right side, but it appears to be filled to the top with the same material.

If anyone is familiar with this type of construction, Its a early 70's Semi-D.. Am i wasting my time. ?

I can just about reach the drill thro the visible blockage, but is there any point if the whole lot is filled ? or if there is another blockage further down. The drill seems to get stuck/snagged about 9" down below the surface

The Continental Op

That might be a bad idea. The chimney works by having a lower pressure at the top that the bottom so the air flows up. Your air coming from above might be taking air out rather than letting it in. afaik air flow for fires should come from below the fire unless its coming from the room.

Markcheese

I vaguely remember "helping " to fit an external airflow for a back boiler , many moons ago ( I was a teen working with my dad )

A "Baxi-box " I think , it was just a metal box under the fire-place connected to a large pipe running under the floor and through the external wall , very low tech ,

If it's a 70s house there's probably not any insulation under the floor , and hopefully you know where any plumbing pipes ect might be , so a consaw may be the way to go ..

Dr Turk Turkelton

If that starting about a metre from the floor and finishing about 1.3m then it's probably a flue gatherer.

You won't be drilling through it as it will be harder than a hookers heart.

whizbang

So after I removed the firebrick and cleared out the firep[lace, I drilled into the side in a few places to have a better idea what was there.

It appears the side walls of the fireplace are double, mix of block on flat and on edge.

Makes sense really since the rest of the 5metre high stack has to sit on it.

So project abandoned. Now i have to butcher another vent hole in the outside wall.