heater exhaust pipe or something?

[Guest]

We have an old camper turned fish house and it has a heater in it. The piping that exits the house has one little pipe surrounded by a bigger pipe. I think that the bigger pipe is the air intake while the small one in the middle is the exhaust, right? We have been having problems with wind getting in. The original set up just had a grate flush with the outside covering the pipes. Then we used a half piece of stove piping covering it from the wind. Well, that works alright but i want something better so the pilot doesn't flutter in the wind. I tried attaching three inch stove pipe to the middle pipe and had a 5 foot vertical exhaust pipe. and then covered it all with a roof flashing. Well the tall pipe creates to much of a chimney effect and sucks too much of the heat out, and it also prevents air from getting in to the intake. So I'm trying to think of way to do this. I've seen on other houses people have mushroom shaped exhaust/intakes. Do you think one of those would work? and where can i get one? thanks for any help at all.

[MNice]

What you have is called a direct vent furnace. Before I would do anything to the venting system, I would make sure the manufacturer would approve the change. they usally have some sort of termination kit to prevent your problem.