Wait, what? Can you explain this please,שואב is listed as a verb on Pealim. Is there way to look up in Hebrew or English the different forms in Hebrew or how to tell? I saw that the active participle form is XXIX But it doesn't apply to all words, so I'm unsure how you'd normally know.
Well, context is king, in this sentence it follows צָרִיךְ, which can govern a noun or an infinitive, but not a finite verb form. And a good dictionary should list the nominal uses of the participles like here שׁוֹאֵב־אָבָק vacuum cleaner, אֶ֫בֶן־שׁוֹאֶ֫בֶת magnet, שׁוֹאֵב־מַ֫יִם water drawer (the person) or שִׂמְחַת־בֵּית־הַשּׁוֹאֵבָה Rejoicing of the Water-Drawing House.