I have installed a 93+% eff that requires Pvc, condensate drain, etc. Here is my problem: There is an offset in the chimhey at the second floor making PVC unusable. Blowing a hole throungh the wall and chimney to make the connections is not possible either. What are other options. An AL29 stainless flexlines will be eaten to quick and wont pass code, are there flexible plastic liners? Thanks.