If you made this purchase in 2017, you would need to add it into your 2017 return. The federal $500 Non-business Energy Property Tax Credit for energy-efficient improvements like windows, doors, skylights, insulation, roofing products, non-solar water heaters, heating, ventilating, and cooling systems wasn't renewed for tax year 2018. See steps to amend a 2017 return below.
For 2018, under the Residential Energy Efficient Property Credit, you can only get a federal tax credit in 2018 for installing alternative energy equipment, such as solar electric property, solar water heaters, geothermal heat pumps, small wind turbines, and fuel cell property.
https://ttlc.intuit.com/replies/6603004