Mechanical Insulation Installation Incentive Act of 201 7 This bill amends the Internal Revenue Code to allow an additional tax deduction for the cost of installing mechanical insulation property. The bill: (1) limits the amount of such deduction to the lesser of 30% of the cost or the reduction in energy loss from the installed mechanical insulation property compared to property that meets the minimum requirements of American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard 90.1-2007; and (2) allows the cost of mechanical insulation property that is placed in service to replace insulation property to be treated as a deductible business expense in the current taxable year. The bill defines "mechanical insulation property" as insulation materials, facings, and accessory products: (1) placed in service in connection with a mechanical system which is located in the United States and of a character subject to an allowance for depreciation; and (2) utilized for thermal requirements for mechanical piping and equipment, hot and cold applications, and heating, venting and air conditioning applications which can be used in a variety of facilities. The bill also allows a tax deduction for capital expenditures related to mechanical insulation property.