Trying to install the vent pipe for my Harman PF100. I am using Selkirk DT pipe from the horizontal termination to the clean-out Tee, then regular VP pipe down to my furnace. I ordered their standard VP pipe connector (part # 4vp-pc) to connect to the furnace exhaust collar but the collar is apparently thicker or oversized...either way, the connector does not fit. I ordered an adjustable connector but it is 2 weeks out...what part do you guys use for this connection?