IQ Pro Power Requirements

I’m considering the IQ Pro as a replacement for my Vista 20P but the power requirements are confusing to me. The system comes with an 18V DC transformer outputting 2.2A with Qolsys saying the panels needs 16-20V at the panel, which equates to approximately allowable ~10% drop. I have a two story with the power run for my existing system being approximately 30-35’ long 4 conductor 22AWG wire. I know I would need to double up the pairs but I get confused with the manuals maximum wire length by AWG for the power requirements listed above. The manual claims that the maximum length for 18AWG is 13’, but when I do the resistance calculations using the permissible drop, I get almost 60’ for the 18AWG and with my doubled up 22AWG coming out to be approximately 50’ maximum run. I was wondering if I’m missing something or are the stated values in the manual overly conservative? I was hoping maybe somebody had experience with this or support might be able to explain the variance.