heft vs heft up

heft is a noun but heft up is not a noun.

Word	Noun	Adjective	Verb	Adverb
heft	Yes	No	Yes	No
heft up	No	No	Yes	No

As verbs, heft and heft up are synonyms defined as:

Other synonyms of heft include heave, heave up.

heft (noun)	heft up (noun)
the property of being large in mass

heft (verb)	heft up (verb)
lift or elevate	lift or elevate
test the weight of something by lifting it