I would be interested in knowing a bit more about this. As a BPI home energy audit and home performance contractor the only way I know of improving the efficiency of a hot water heater is to A. Turn down the thermostat, B. Flush it on a regular basis, C. Install a power vent system. D. Install an additional thermal blanket around heater. E. Replace the unit with a heat pump assisted unit, or Geo-thermal system. Or on demand unit.
I have never heard of doing anything that would make the existing heater increase to a EF of 2.
if you would like to review details of this machine simply pull up : airtap a7 & it takes you to LOWES & scroll down a few lines & there are several items of info & also you can pull up specs. if you are able to learn more pertinet info i would welcome your further comments thanks charles