Refinance primary residence to pay off rental properties

[Dhiraj Chhabra]

I paid off my primary residence 3 years ago. I own 2 rental properties(1 single & 1 duplex). Loans on both are in total equal to 60% of my primary house value. 

Both of them are at 4+ % . Since the rates are so low, should I refinance my existing house at 2.8% to pay off my investment properties. Just coz debt will be cheaper.