I recommend not looking at the Zillow estimate at all. It is often completely wrong about estimated home value. What ever flawed formula Zillow uses to estimate home values, it does not take into account most of the relevant factors that typically are considered when evelauating market value. It would not know to look at surrounding areas if there are no close comparables present, neither would it take into account seller concessions, short sales, condition of the property, and many other important factors. that's not to say that your appriaser is right. I recommend you try to refinance with a different lender, you may be surprised that the value may be much different with another appraisal as often happens today. However, you should definitely consult with me, or any other professional real estate broker on Staten Island about the home's value to make sure that efforts would not be in vain. If your broker tells you there are no comparables and the value is way below what you need to refinance, it is likely that the appraiser will have an issue as well.