Fireplaces, Heating Stoves, Flues and Chimneys - garage to house wood heat

I am installing a Norsman 2500 wood furnace in my detatched garage and plan on piping the heat to my house roughly
25' away. The furnace has dual 8" heat outlets on the top. I plan on converting the two outlets into one by using simple sheet metal duct work. My question is what is the BEST and most ECONOMICAL way of doing this, what type of pipe to use(rigid,insulated flexible), diameter to use, (keep distance, and air volume in mind). Underground verses above? Once inside basement, I plan on tieing into existing duct work(bypassing central furnace plenum) The wood furnace has dual blowers but do not know exact combined C.F.M output. I understand and know about my cold air return system and will have that part under control. In a nut shell, I just need to get heat from garage to house without heat loss and air volume through restrictions caused by diameter and distance.

Well, I'm not going to be able to engineer this for you, but I will comment. Under ground for sure. You will be facing a more consistent temperature and warmer, when it counts. Size will be critical on the supply and even larger for the return. The insulation will have to be very good. The fan that comes with the furnace probably will not be big enough. You are starting with 100 sq inches (two 8” ducts) and feeding say a 300 sq inch hot air duct, so your air speed will already be 1/3. Add in the loss for the 25’ out and back and it may not meet your expectations. Don’t take my word on it, I love wood. Let’s hear what the pros have to say.

Bud