Depreciation of Primary Residence converted to a Rental

[Zac Newell]

I bought a house in 2009 for 170k as my primary residence.  In 2015 I converted that house to a rental.  When it was converted to a rental the property was worth ~250k.

For depreciation can I use the 250k value when the property was converted to a rental or do I need to use the 170k purchase price?