Ability of using equity to finance down deposit on new home?

I just did that about seven months ago...except I went from a duplex to a single family home. The major advantage of using you equity to purchase more property is that you can avoid pmi with 20% down and conventional financing. The major disadvantage is that a home equity loan is fairly expensive. I borrowed 90k against my equity and it costs me almost $700 a month. I bought my new home through a bank and got approved before the home equity loan even hit my credit so they couldn't complain about it! If you think your duplex will cover the cost of the mortgage and the home equity loan than go for it! Otherwise you will be footing the bill for the second mortgage on your primary home. Good luck and hope this helps.