If we replaced an existing gas furnace with a new, more efficient furnace, how do we ensure it qualifies as energy saving?

[CarolC]

For 2017, your new gas furnace needs to meet the following requirements:  AFUE >= 95.  You can check your product documents to see if your furnace qualifies.  Also, the manufacturer is required to provide a certification statement if it does.

"A Manufacturer’s Certification Statement is a signed statement from the manufacturer certifying that the product or component qualifies for the tax credit.  Manufacturers should provide these Certifications on their website. Call the manufacturer, or search their website. EPA does not have copies of the Manufacturer's Certification Statement.  Taxpayers must keep a copy of the certification statement for their records, but do not have to submit a copy with their tax return."

The maximum Tax Credit Amount for your furnace is $150.  Click this Energy Star link for more information:  https://www.energystar.gov/about/federal_tax_credits/2017_non_business_energy_property_tax_credits.