We had our electric bill go down by 1/4 after installing our AO Smith Signature 900. Then the heat pump broke 13 months into a 12 month labor warranty (it no longer blew cold air, so it wasn’t working). We found out nobody even fixes the heat pump part. AO Smith agreed to take it back and refunded us but we had to hire a plumber to put in another one, this time a less expensive one.