The IRS doesn't publish a list, it's not their job to keep track of appliance manufacturers.
The rules state that "The Uniform Energy Factor of an electric heat pump water heater must be at least 2.2."
The UFE may be on a label on the unit. If not, you may need to
contactthe installer or manufacturer.
It's not an electric water heater. I see where you are getting this information and the next line states "an electric heat pump that achieves the highest efficiency tier established by the CEE as in effect on Jan 1, 2009. Seems very vague. The product we installed did rate as Energy Star.
Unfortunately, the EPA energy star designation does not always track with tax law. The energy star website may have more information that will help you, or you will have to check with the manufacturer or installer. (It’s not really vague, it’s about as specific as Congress could have made it in 2009. The problem is that we don’t have the CEE standards memorized).