I saw a TV show where some plumbers helped a home owner who had really high bills hook up a small heat pump to his water heater. I can't for the life of me find anything online where I could go watch it again. They plumbers on the show recommended doing it that way over the combo unit that you can purchase. Can anyone tell me where I can find out how to do this? I have a big plain old electric water heater now and want to add the heat pump to it.

Thanks in advance.