Raising rent mid lease

[Scott Dougherty]

Hi, I am new to bp but like the site a lot. I have a four unit building with window a/c units in each of the units. I would like to install central air for each of the four units. The building already has furnaces so vents are in shape. I would also like to raise the rent by $50 a month for three of the tenants to offset the costs for this upgrade. What's the best way to pose this to my renters? They are under a 12 month lease for their current monthly rent. Thanks Scott