Advice for gas chimney

I'm thinking of putting a canopy over our back door, and possibly building a covered walkway between the house and our garage, the walls of which run parallel and about 3 feet apart. However there's a problem in so far that the central heating boiler chimney exits alongside the back door, and this would end up with the chimney venting into the canopy/walkway. Obviously I'm not going to do that!
There's also an extractor hood vent the far side of the back door, but I'm more comfortable with extending that if I need to.
Here's a couple of pictures of our back door with the chimney clearly seen to the left:
http://www.yorkshireplace.co.uk/Door.asp
I know it is possible to install a vertical extension to a CH chimney because a place down the road has got one, but never having delved into this sort of thing before I'm not familiar with what can/can't be done. I'm assuming that if I were to extend the chimney then I have to take care that the chimney can "breathe" in and out, plus whatever I mount around the chimney (in terms of canopy/roof) has to be acceptably fireproof.
The CH boiler is a Potterton PrimaF if that makes any difference.
Advice would be welcome. Does this require a gas fitter to do the job to ensure it is done right, or is it in the realms of general DIY?
PoP
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Would the canopy come out to the side as far as the pipe ? It looks to be far enough away from the door to fit a small canopy beside it. Is the door to the garage opposite the kitchen door ? Or are you thinking on covering the whole gap between the buildings some how ?
The flue pipe needs to be sealed with the correct paste stuff at any slip over joints, so you might need the help of someone who knows about these things. But I do know that it is possible to have a least 2mtrs of flue from most of the standard boilers without needing extra fan assistance and things. So, the next questions are, how far away from the wall is the boiler ? And would any extension to the existing flue, take it over the nominal 2mtr length ?
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On Fri, 17 Oct 2003 23:08:26 GMT, "BigWallop"

The flue is roughly about the place where I was thinking of adding a door to the (newly) covered passageway.

I was thinking that maybe a 90 degree bend to take the flue to vertical, and then 1m with a raincap on top.
Haven't discussed this with SWMBO yet. That'll probably be met with the same argument about us getting a small dog. Why are some people so alienated by a dog yet they wax lyrical about getting a cat? I can't stand cats because they are so damned independent.
PoP
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PoP wrote:

Actually the boiler instructions are likely to permit the flue to discharge into such an area [1] except for one problem - you need 1200mm from all the openings. You would seem to currently have about 500mm to the door.
You will need to look at the installation instructions for the boiler. It is likely that a flue with two 90 bends (one inside and one outside the house) and a vertical flue terminal will comply.
You will need to obtain the flue parts ( 1 bend, 1 vertical terminal, 1 extension peice to replace the existing horizontal terminal).
First you need to really checkout what possible in the instructions, they might require a minimum 600mm horizontally to the walls - both of them - which could be the problem. 8-(
The vertical terminal will be designed to go through a wooden deck - the flue/duct does not get hot because the flue is inside the duct.
The physically hardest part will be getting the old terminal out of its hole - it looks like it's been cemented in.
However unless you are competant to work on gas appliance flues you best get in a pro.
[1] "Car ports" are defined as having having a roof and open on 2 or more sides.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
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On Sat, 18 Oct 2003 09:22:23 +0100, Ed Sirett

I email'd Potterton's last night to see what they have to say.
Found an online manual for the Prima 'C' boiler and references on the web to Prima 'D' and 'E', couldn't find a reference to Prima 'F' anywhere. I assume it'll be the same basic boiler with slightly enhanced specs.
PoP
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