Occupancy Permit Pittsburgh approved as 2 unit county site says 3

[Jim K.]

I'm currently under contract for a 3 unit building in Pittsburgh Pa.   The occupancy permit is for 2 units.   The county tax website is saying 3 units.    I called the zoning office to see what was going on.  They than told me that it is only approved for 2 units.  If I want to rent it out as 3 units I would need to install a sprinkler system.   I spoke to the current owners and they told me since they've owned they have always used it as a 3 unit building and never had an issue.   I don't think I want to attempt to travel down this road.   What is the possible penalty for renting it as a 3 unit when only approved as a 2 unit.   The gas and electric are separated so I would think the city had to know what was going on. I'm to the point where I wouldn't cash flow what I would need to be profitable only renting 2 of the units.    Any advice or tips would be greatly appreciated.