Hello! I have a house with triple wall chimney pipe installed with a thimble through the exterior concrete block wall, however, there was no stove! I was able to purchase a new stove at Home Depot at the end of last season for $100, but they had no pipe. I need to install double wall pipe but cannot find a reducer to fit the thimble. Can anyone recommend a company where I can purchase a reducer; 7.5" to 6", and 6" double wall pipe and a 90* elbow, from the stove up and into the thimble? Since I am a total newbie, I have attached several photos for anyone's consideration. Thank you all for any help/direction you could provide me. - Dan