There are a lot of clunky old pool heaters on the market, and a major utility company wants homeowners to upgrade.

SoCal Gas, the nation’s largest natural gas utility, is offering $300 rebates on natural gas pool heaters that have a thermal efficiency of at least 84%. The utility offers an even more generous kickback of $750 for so called ultra-efficient heaters, which boast an efficiency rating of 94% and higher.

A caveat: Rebates only apply when homeowners replace existing heaters with one of the more than three dozen qualifying models. Folks who didn’t previously own a heater do not qualify.