On the page Enter Your Qualified Energy Costs use the box labeled Water boilers for the cost of the furnace. The box needs to be re-labeled. If you click on the Learn More link it will describe -
Enter the amounts you paid for a natural gas, propane, or oil furnace or hot water boilers...
That is the correct location to enter the furnace cost as it will flow to the Form 5695 Line 24a for Enter the cost of natural gas, propane, or oil furnace or hot water boilers
If you were eligible for this credit but did not include it on the 2023 tax return that you filed, you can amend the return for the credit.
If the return is accepted you will have to amend your original tax return. An amended return, Form 1040-X, can only be printed and mailed to the IRS if the original tax return was not e-filed. The IRS will take up to 20 weeks or longer to process an amended tax return.
Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed by the IRS.
See this TurboTax support FAQ for amending a tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...
