Help please. Rayburn flue through hole in chimney breast

[fenwoman]

Right, I got the old rayburn in place and have the flue. I measured up and with my new angle grinder, plus some nifty hammer and bolster work, have made a hole in the right place up the chimney breast. The only problem is, because the top part of the flue pipe is a 45 degree angled section, instead of making a nice straight hole through, I had to make it oval to account for the angle. The problem is now that I have quite a gap around the flue and don't know how to fill it to make a seal. It will take far too much fire cement. I have some fireproof plasterboard but I've wasted flipping loads today cutting out a tidy square, and trying to cut a hole for the flue in the right place.
Is there any kind of heat resistant expanding foam filler? If not, how else can I fill the big gap. I'm not an expert DIYer, more an enthusiastic one who will try most things but I just can't seem to work out how to overcome this problem and the more I think about it, the less able I am to see a way around it.

 

[stuart45]

Can you get a photo on of what you have done?

 

[fenwoman]

 

[Estrella]

Can you not get some half bricks in there and the fill the small gap that is left with fire cement? You could also cover what you have done by fitting a top plate (designed for sitting on top of a chimney).
You can see one here > http://www.fluestore.com/index.php?page=info&grp=1&subgrp=1&diam=155&leaf=1&all=ALL&code=20-150-P

 

[Estrella]

Have you also checked the chimney condition for leaks ? Are you fitting a flexi flue. As far as I am aware you should also backfill the chimney from the ground up to just below where the flue enters the breast.

 

[stuart45]

When you take the flue in like this the bend must be 45 degree max and have a cleaning eye on the bend. It needs a wall sleeve and rope seal where it goes through the wall and the pipe has to be cut flush with the inside of the chimney. There must also be a debris collection space with an access door for cleaning.
You need to brick in the hole slightly to fit the sleeve.

 

[fenwoman]

Can you not get some half bricks in there and the fill the small gap that is left with fire cement? You could also cover what you have done by fitting a top plate (designed for sitting on top of a chimney).
You can see one here > http://www.fluestore.com/index.php?...diam=155&leaf=1&all=ALL&code=20-150-P[/QUOTE]

I may have to do the brick and fire cement thing. The top plate would be a great idea with a 90 degree angled section but because I used the 45 degree one, it makes life awkward as it goes up at a slant as it enters the brickwork.

 

[fenwoman]

Have you also checked the chimney condition for leaks ? Are you fitting a flexi flue. As far as I am aware you should also backfill the chimney from the ground up to just below where the flue enters the breast.

The rayburn is replacing another rayburn which was there. The chimney doesn't leak. I didn't backfill with the other rayburn but the flue went straight out the back of that one. I haven't backfilled this time either and am expecting it to work as well as the previous one did. I may get a flue liner at some point when I have spare money.

 

[fenwoman]

When you take the flue in like this the bend must be 45 degree max and have a cleaning eye on the bend. It needs a wall sleeve and rope seal where it goes through the wall and the pipe has to be cut flush with the inside of the chimney. There must also be a debris collection space with an access door for cleaning.
You need to brick in the hole slightly to fit the sleeve.

Yes it does have a cleaning door on. What is the wall sleeve for?
The soot collection access door will be built later this year some time on the outside wall of the house. I already sweep my own chimneys so making life easier for me will be a priority.

 

[stuart45]

The wall sleeve allows for the flue pipes expansion which can cause slight fractures and leakage. You should also try and avoid 90 degree bends.
BoxCleva is correct about filling the flue.