manual-
https://woodstovepro.com/store/pdf/BreckwellP24OwnersManual.pdf
I think I better understand this now,
@Joey15 yes your on the right track, the install your doing is what the manual call "built ins" and the manual states that you need to make a hearth using 8" hollow blocks topped with a continuous top sheet (non combustible) so think hardy board then tiled with continuous grout so no embers can fall between the cracks. The side clearances to a combustible wall are 5"
Since this is a powered vent you can either vent horizontally (kit) or vertically (kit) with the vertical vent you will probably use more pipe since your saying you have a 26ft chase, now pellet vent needs to be installed a minimum of 3" clearance from combustibles, and you should factor in installing a second pipe for "outside air connection" so you burning out door air and not indoor air as the manual eludes to.
As far as installers, please make sure they are csia certified and you pull all required permits and have all required inspections.