I believe high efficiency furnances must be vented horizontally through a wall.
Can you vent a gas furnace through a wall.
I have not heard of high efficieny only lasting 10 13 years.
These ventilation pipes should be isolated from the furnace combustion chamber and made airtight to eliminate the possibility of combustion gas leakage.
The answer is yes and no.
Gas furnaces usually come with their own specifications.
Distances pertaining to the furnace combustion air intake and exhaust vent distances from the indoor furnace cabinet itself and nearby surfaces materials or combustibles.
Adhere to them even if you are building the vent on your own.
So what does this mean.
Proper sidewall venting requires installing separate vent pipes horizontally so that they vent to the outdoors through a wall of your home.
Only units designed for it can have a vent go thru the wall and end there without a vertical stack.
When installing a direct vent wall furnace there will be two sets of clearance distances that must be respected.
An 80 efficient furnace can be side wall vented per national fuel as code 7 3 4 with the use of a mechanical draft system of either forced or induced draft design.
I would be very leary of a hvac contractor would not do this.
You can go through the wall then run a vent pipe straight up above the roofline.
I think don t it is possible to vent a 95 efficiency furnace up through an existing chimney.
You cannot just take the vent off an 80 efficient furnace and run it out a side wall.