Sounds like you have a nice house! Zillow is obviously wrong about the rent Zestimate. A house that is 3X in size and is similar condition should command a lot more rent than a smaller one. Probably not 3X times in rent, but considerably more than the smaller house. Just look around local rent listings to see what your house should rent for. Rent prices are a very localized thing based on neighborhood, access to transportation, and of course demand.