Venting a Water Heater Horizontaly

Hello,

I currently have a hot water heater that is vented through the chimney. The manufacturer states that it is a 3 inch Type B double wall vent system. I installed it earlier this year and vented it the same way the prior one was hooked up.

I would like to change this and vent it horizontally outside the house. The only wall I would have to go through is an exterior wall. It is about 8' to the side wall.

There is currently a high-efficiency furnace that is vented horizontally outside. I really want to cap off and insulate my chimney after I solve my new venting problem.

Thanks for you help,

BV