Piggyback HELOC — Credit Union West is a home equity line of credit from Credit Union West. The ongoing APR is Variable interest rates are calculated as the index plus a margin, with a floor of 4.25% APR and a ceiling of 18.00% APR.. Loan terms: HELOC purchase money second products have a 20-year draw period with a balloon payment at maturity, amortized over 30 years..