Ventilation For Bricked Up Fireplaces

[paulh53]

Hi Gang
Three years ago, My partner bought a house which had two fireplaces, She promply had these removed and bricked up by a local builder,
I always thought that you had to fit ventilation bricks when fireplaces had been sealed up to allow the chimney to "breath",
Both chimneys are still open at the top,
One of the fireplaces is in our kitchen, And has new kitchen base units fitted against the "sealed up" fireplace, And there is a smell of damp in the base unit,
Should I call the builder back? Even though it's been almost three years?

 

[renovator]

Hi Gang
Three years ago, My partner bought a house which had two fireplaces, She promply had these removed and bricked up by a local builder,
I always thought that you had to fit ventilation bricks when fireplaces had been sealed up to allow the chimney to "breath",
Both chimneys are still open at the top,
One of the fireplaces is in our kitchen, And has new kitchen base units fitted against the "sealed up" fireplace, And there is a smell of damp in the base unit,
Should I call the builder back? Even though it's been almost three years?

paul, this should help.

 

[gme106]

renovator, I have also had two fireplaces removed and bricked up and as in paulh53's case there was no air bricks used. The chimneys have also been caped off using a mushroom shaped cap. This was done 3 years ago and I have had no problem with damp. However on the sides of the two chimneys there are holes drilled through where old pipe work etc, used to be and was wondering would this be acting as the ventilation
Would you still recomend adding an airbrick

 

[renovator]

renovator, I have also had two fireplaces removed and bricked up and as in paulh53's case there was no air bricks used. The chimneys have also been caped off using a mushroom shaped cap. This was done 3 years ago and I have had no problem with damp. However on the sides of the two chimneys there are holes drilled through where old pipe work etc, used to be and was wondering would this be acting as the ventilation
Would you still recomend adding an airbrick

sweeping, capping and ventilation are the keys to trouble free fireplace closure.

the soot needs to be swept out as is contains cenospheres, microporous components that love moisture. the chimney is generally lined with soot and over time the soot holds moisture against the mortar. As the mortar ages you find a heap of soot and sand in the hearth. Capping prevents undue drafts and water ingress.

ventilation allows any mositure to evaporate.

If you are vented and cleaned and capped i doubt you will see any issues.

 

[GwaiLo]

Paul and gme106,
It really is essential that the chimney is fully ventilated and the reason is simple. Ventilation keeps the inside of the chimney dry.

What happens if the inside of the chimney isn't kept dry is less simple and is also not explained on the otherwise very helpful link that renovator posted.

When your fireplace burned coal the by products included sulphur dioxide (SO2) and nitrogen oxides (NOx) the soot in your chimney contains them still. These are the reasons you must ventilate. If you fail to do so and moisture is allowed to accumulate the PH (acidity) of the moisture will be raised by the SO2 and NOx and the water becomes acidic enough to eat away at your brickwork and mortar. Of course you might get lucky and see some damp patches on the chimney breast before any serious damage occurs, but then you might not. Essentially what you have created by not ventilating is a mini environment that is full of acid raid. If you want to see what that does to bricks and mortar take look at this site http://www.doc.mmu.ac.uk/aric/eae/Acid_Rain/acid_rain.html

I was not aware that cenospheres were produced in domestic chimneys as they are a naturally occurring by-product of the burning process at coal-fired power plants. They are produced at the high temperature of 1,500 to 1,750 degrees Celsius, a good deal hotter than a domestic flue gets I would have thought? However, I could be wrong about that.

Cenospheres arehollow spheres comprised largely of silica and alumina and filled with inert air or gas and are inert themselves. So they aren't going to react chemically with anything. Cenospheres are waterproof, innoxious, and insulative though so I am unsure as to how there presence would dictate the need to ventilate. The only possible relevance I can think of is that Cenospheres might contain SO2 or NOx, but if so it is the SO2 or NOx that is the problem rather than the cenospheres.

I really ought to know the answers to this one so I'd be happy to be enlightened if you know something I don't renovator.

 

[renovator]

Paul and gme106,
It really is essential that the chimney is fully ventilated and the reason is simple. Ventilation keeps the inside of the chimney dry.

What happens if the inside of the chimney isn't kept dry is less simple and is also not explained on the otherwise very helpful link that renovator posted.

When your fireplace burned coal the by products included sulphur dioxide (SO2) and nitrogen oxides (NOx) the soot in your chimney contains them still. These are the reasons you must ventilate. If you fail to do so and moisture is allowed to accumulate the PH (acidity) of the moisture will be raised by the SO2 and NOx and the water becomes acidic enough to eat away at your brickwork and mortar. Of course you might get lucky and see some damp patches on the chimney breast before any serious damage occurs, but then you might not. Essentially what you have created by not ventilating is a mini environment that is full of acid raid. If you want to see what that does to bricks and mortar take look at this site http://www.doc.mmu.ac.uk/aric/eae/Acid_Rain/acid_rain.html

I was not aware that cenospheres were produced in domestic chimneys as they are a naturally occurring by-product of the burning process at coal-fired power plants. They are produced at the high temperature of 1,500 to 1,750 degrees Celsius, a good deal hotter than a domestic flue gets I would have thought? However, I could be wrong about that.

Cenospheres arehollow spheres comprised largely of silica and alumina and filled with inert air or gas and are inert themselves. So they aren't going to react chemically with anything. Cenospheres are waterproof, innoxious, and insulative though so I am unsure as to how there presence would dictate the need to ventilate. The only possible relevance I can think of is that Cenospheres might contain SO2 or NOx, but if so it is the SO2 or NOx that is the problem rather than the cenospheres.

I really ought to know the answers to this one so I'd be happy to be enlightened if you know something I don't renovator.

The reference to cenospheres is as a result of my thesis at UMIST discussing the affect of chemical weathering on natural stones
and focussed on the effect of fossil fuel pollution i.e. everyday burning coal fires in northern terrace houses. The combustion by-products being as you detail so2 and nox but also particulate components within the soot called cenospheres.
These combustion particulates (Dryer and Kerho (1987)) ".. contain all the non-soot carbon and also part of the ash material. Such particles are nearly spherical, hollow and porous, and they range in size from 1 to 100 µm. They are called cenospheres. "

It does appear from a brief literature review that the term cenosphere does define a broad range of tiny particulates

As the soot may contain cenospheres the moisture from them could fuel the so2 and nox reactions in addition to any additional free vapour.

the need to ventilate is agreed entirely, but I would advocate sweeping everytime.

Also this can be a good indicator of so2 and nox at work.

 

[GwaiLo]

I hope you had fun researching it renovator. I had a great time with mine, the only chance I have ever had of really reseaching something thoroughly. I did mine on managing asbestos in buildings and predicted that the government would eventually introduce new regulations requiring asbestos registers to be compiled and maintained because of the increases in Mesotheliomas in construction workers. The only thing that suprised me was that they didn't do it until last year (my dissertation was written in 95).

Anyway, I'd agree about sweeping the chinmey prior to closing it up. I am still unclear if you are saying that cenospheres themselves have a detrimental effect or just the SO2/NOx. I guess if cenospheres are hygroscopic (are they?) that would make things worse, but I still don't get how they can cause any damage themselves.

 

[renovator]

the cenospheres are hygroscopic and so may supply moisture to fuel so2 and nox reaction.

 

[antinator]

renovator how do you know sooooo much about diy ????
what is your job????



also thanks for helping me with those questions i needed want more?