See p.28 of the manual for the generic code clearances to doors & operable windows. (IIRC MA follows the standard US restrictions on those.)
The venting clearance requirements are specific to the venting terminal model used. Figure out which your using, see if the venting instructions for that version can be found online.
Local inspectors might take a different view, and adhere to the clearances for separately vented (not direct-vent), which can be found on p14 of the Takagi installation manual. (When in doubt...)