Venting pvc size on 96% 80k btu infinity mvb furnace also water heater flu - do I need liner?


Installing a infinity 96% efficient furnace, will have two pvc's for venting. It's about 16' run from the exterior. Will need to stub out with 45 and then another 45 to get it going ups the a 90 deg elbow heading out and then an offset (which is another 2 45 deg pcs) respectively 3 90's in a 16 foot run to the outside wall - not including anything outside...

On the Infinity MVB080 is it better to go with 2" , 2 1/2" or 3" is there a benefit to the larger pipes...?

I understand there is a sizing table, does it make a difference if you're pushing the limit or is 2" gonna work regardless?

Also the water heater, will I need to install a liner in the existing B- vent stack from the old 80% furnace? I believe the B-vent is 5-6" we live on IL/WI border so the winters are cold?

Seems it is necessary until they look at how much of a pain it's gonna be then I hear, you should be ok with the b-vent the way it is...

Don't want to cut corners w/co