I'm new here so bear with me. I am building a house and put in a Englander pellet stove....first pellet stove I've ever had. I had the builder install a Selkirk/Metalbestos L vent for outside venting and installed the outside air kit. The pellet stove sits in a corner at an angle. I need a flex pipe to attach the stove to the vent system. Where can I get one? The Selkirk site isn't exactly friendly. Thanks in advance!