Fireplace problems

[Michelle]

Hi

I would really appreciate some advice. We live in a mid-terrace cottage built some time around 1800 - 1835, I believe. We removed a small 1970s fireplace, removing the usual rubble (broken breeze blocks etc.), to reveal the older fireplace behind, and have swept the chimney. The 1970s fireplace was used regularly until recently by the previous owner. Now the fireplace doesn't draw properly and just smokes too much. We've tried a couple of different grates at various heights, but nothing has worked and it's just too poor to use. There is no other form of heating in the cottage, so we need a fireplace that works as well as possible throughout the winter months. We have a good flow of air in the sitting room - plenty of drafts!

The fireplace opening measures:
Height 3'9"
Width 3'5"
Depth 1'8"

Our chimney stack, which is brick and looks like it was rebuilt during the last 50 years, might need repointing; my partner is pretty certain that smoke is leaking through broken mortar. Could having the stack repointed make a huge difference to the effectiveness of the fireplace, or is it likely to be a combination of factors hindering its efficiency?

I would like to have the stack repointed in lime instead of cement - does anyone know someone in the South Somerset / North Dorset area who is a bit of a fireplace expert and won't add cement to the mortar when I'm not looking?

Could it also be that the current chimney pot is suitable for a small grate and not for a larger opening? If so, what kind of chimney pot is required?

And might there be a problem with the flue lining which could contribute to the problem?

Thank you

 

[Lime]

Have the chimney swept.
Ensure the brush shows out the pot.

If you are expecting the hole left after removing the 1970s fireplace to work properly by itself as a fireplace, it won't.
All open fires need a flue construction that "encourages" the smoke to go up the chimney and that is usually achieved by a form of restriction just at the top of the opening.
The restriction (venturi) speeds up the flow of air and in the process lowers the air pressure in the area so encouraging all the smoke to go up the chimney.
http://en.wikipedia.org/wiki/Venturi_effect

 

[ian]

I think this is right, don't try to use too small a chimney pot on top as you create another venturi that reduces the effect of the lower one. Go with the one at the fire "throat" and don't choke it again at the top. Once you have the flow let it go. The guys who installed our 18" liner on a 10ft inglennook removed all obstructions above the fire hood and it works a treat

 

[MdB]

Nemesis posted a good set of links for chimneys here:
http://periodpropertyshop.co.uk/phpBB2/viewtopic.php?t=8311

There is also an exciting document here:
http://www.planningportal.gov.uk/england/professionals/en/4000000000503.html

 

[Nemesis]

And here's another link:

http://www.boreme.com/boreme/funny-2007/man-stuck-in-chimney-p1.php

 

[Michelle]

Thanks for your replies.

Following on from Ian's useful advice on chimney pots, I'm wondering how you know which style of pot is the most sensible. There are so many varieties available.

 

[ian]

I'm afraid that is the jist of what I remember from the company that fitted the liner. Ask an expert at a stove installer for proper advice. We had a big frying pan cowl on the top originally in the hope that it would draw by a venturi there. When it came down it was 10 lbs heavier with tar and soot. An "oh no guv, you don't want to do that" moment.