Wood-burning stove - buried air supply?!

Hi,

We are just about to order a wood-burning stove and, before the installer arrives, i want to sort out the constructional hearth. This raises a couple of questions.....

1. Our chosen stove, the Contura i5, requires an "air connection for optimum function and efficiency", measuring 100mm diameter for lengths of over 1 metre. I was thinking of routing this beneath the suspended timber floor of the room in which the stove stands. This seems to have the advantage of ensuring that the air under the floor is regularly changed and may, thereby, improve the existing underfloor damp problem. Opinions?!

2. If we go for this underfloor route, what should the duct be made from? Given that it has to pass down through the concrete hearth i was doubting whether aluminium or steel would have enough strength. My only other idea though was using either ceramic or plastic (!) drain pipe - at least for the sections that will be buried. This seemed a bit odd, so i thought it best to get an expert opinion.......

Any help hugely appreciated!

Crawf