Look up drain/fill procedure at newtis.info; you don't need vac device to fill but that device would speed the process and minimize air entrapment.
In lieu of that, manually fill via expansion tank (slowly) and run bleed procedure, maybe two time to insure all entrapped air is vented.
https://www.newtis.info/tisv2/a/en/f...check/EQpQ78sM
https://www.newtis.info/tisv2/a/en/f...check/GTm6KJxt