Looking at the manual on HHT's website, the 52I insert being installed into the zero clearance cabinet PN, the instructions are with the zero cleance cabinet. This info is from page 12 of the 52I manual..
Installing the Accentra 52i Pellet Insert into a Harman Zero Clearance Cabinet
If you don’t have a factory built fireplace or masonry fireplace, the Accentra 52i Pellet Insert can also be installed into the
Harman Zero Clearance Cabinet, Part # 1-00-574323. This is the
only permissible way to install the Accentra 52i Pellet
insert
without a suitable fireplace. After the Harman Zero Clearance Cabinet is installed, type PL vent pipe, wall pass-throughs and
terminations are used (
Note: Flex pipe is not approved these types of installation). Detailed installation instructions are included
with the Zero Clearance Cabinet. These same installation instructions can also be found on-line at
www.harmanstoves.com.
Below are two sample installations using the Harman Zero Clearance Cabinet.
PL Vent Pipe installed through a ceiling. PL Vent Pipe installed through an exterior wall
Harman