Avoiding Balloon Payments For Owner Financing

[Brian Ortiz]

I saw a couple of online sources that advocated a graduated payment strategy as an alternative to offering a seller a balloon payment in an owner financed deal. The deal has a constant 5% interest rate, but to entice the seller to sell, we would increase the monthly mortgage payment by 14% a year for years 2-5. The purpose of this would be to shrink the number of months until the loan was paid off and provide a higher average payment to the seller. It's an easy calculation to make if the interest rate is zero, but it seems to get sticky when the interest rate is not zero. Here's the deal specifics:

150,000 loan
30 year amortization
5% interest rate 
No Balloon Payment 
monthly mortgage payments increase 14% per year for years 2-5 and remains at the year 5 level for the remaining payoff duration of the loan.  

So -- how many months until this loan is paid off considering the above numbers?

Also, if there are any other viable alternatives to offering a Balloon Payment I'm all ears -- 

Thanks!