Due to the fact that a HELOC is a line of credit based on the equity in your home, lenders do require an appraisal. To calculate the available equity, the lender will need to confirm the value of your property as well as your current mortgage balance.
If your appraisal does not confirm the value of your home, you may have difficulty obtaining your HELOC. The lender requires enough equity so that if you default on your loan, it can recoup the outstanding debt even after your mortgage has been paid off.