Can a chumash be used for a public torah reading?

Question

I recently attended a weekday morning minyan where the Torah reader was reading simultaneously from a sefer Torah and a printed Chumash. It appeared that the person was mostly reading from Chumash and moving the yad to follow along in the sefer Torah. The usual liturgy before and after the reading was said as were the blessings before and after the aliyot. Is this a valid practice?

Answer 1

The Rama (OC 143:2) writes:

בחומשים שלנו, אפילו כל ה' ספרים ביחד אין לברך עליהם, ובמקום שיש ס"ת ואין ש"ץ הבקי בנגינה בעל פה, ראיתי נוהגים שהש"ץ קורא מן החומש בנקוד והעולה קורא אחריו מן הס"ת הכשר.‏
In our Chumashim [which are printed] even if all 5 Books [of the Torah] are included, one cannot recite a blessing over [reading from] them. In a place with a Torah Scroll but the leader doesn't know the cantillation by heart, I have seen a custom that the leader reads from a [printed] Chumash with vowels-points and the one receiving the Aliyah reads [word-for-word] after him in the kosher scroll.

I can't comment about the specifics of your case, but in general one may not recite the blessings and perform the standard Torah service using a printed Chumash^[1]; however, when no one has prepared the reading, it's possible to have a prompter use a printed Chumash so long as it is read for real out of the kosher scroll.

^{[1] Reading from a written Chumash is a whole 'nother story, but you don't see those around too often anymore.}