Whether you pay for the installation of the 220 v outlet or your tenant with respect to the dryer purchased by the tenant depends upon what your written lease says on the subject assuming you have one with your tenant.If the lease is silent on the subject on the issue of installation then you should not be responsible for such costs. If the lease states whose responsibility it is for the installation of the 220 v outlet, then that provision controls.In order to avoid a dispute with the tenant, I suggest you and the tenant evenly split the costs for the 220 v hook up for the dryer that the tenant bought. Had you bought the dryer, you would have been out the costs for the appliance.