RSF Opel 2 Plus in exterior wall w/exterior 25ft chimney

[Norske]

Looking to install a new RSF Opel 2 Plus and wondering if there is anyone else with a similar configuration who can help ward off the gremlins that may plague this setup. Here are the details:
1. Exterior wall install
2. Chimney will be completely exterior, so firebox will hang off back wall of house and we will build siding/roof around it.
3. Chimney will run up 25 ft to steel roof peak and then standard run above it to chimney cap. Chimney comes out of roof/siding protecting firebox and runs UNCOVERED up the rest of the way.
4. Chimney will have a couple 45 elbows in it to gain clearance from house then again to clear roof eaves.
5. US location, so this will be the Opel with the catalytic.

Anyone have an install like this? Care to share pics? I haven't seen one done quite like it but according to RSF specs it should be ok. Wondering a few things:
A. How does RSF brand insulated chimney perform in an exterior installation unprotected from the elements?
B. Any problems with drafting with a "cold" exterior chimney in a ZC unit like this?
C. This is first catalytic unit I have had. Should I purchase a couple extra catalytic replacement elements to have on hand? What happens if I have to burn without one?

Thanks all! This forum has been absolutely the best resource on the 'net.

 

[begreen]

ICC Excel is a good quality chimney product. It will last for years if not decades. I am confused a little by the description. Will the chimney have a chase surrounding it until past the rooftop? If so, that chase can be insulated to maximize performance. Note that the maximum angle elbows for an offset in the US is 30º. 45º chimney LBs are only permitted in Canada. With a 25' chimney the draft should be strong. The fireplace should have an outside air connection. The catalyst life will depend on the fireplace operation and hours of use. Figure about 12,000 hrs of active cat time for its life.