I am confused here, I thought the inclusion of 'voi' (and it being optional) would make the phrase look like, "Voi încălziți apa?" -- how come 'voi' comes afterwards? Is it because this is a question, thus altering the placement of words?
Thinking this, I first thought this would translate as "You heat your water?" (excusing the incorrect possessive, I tried to fit the 'second voi' in)
Thanks for the help
Yes, you guessed right, it is because it is a (real) question. There at least two ways for a question, one where you change the word order and one where you just change your accent (at the end of the sentence). i.e:
Do you heat up the water? - Încălziți voi apa?
You heat up the water? - Voi Încălziți apa?
But with dropping the pronoun in Romanian both look the same "Încălziți apa?"