saw an ad for this new energy star rated electric hot water tank

http://www.geappliances.com/heat-pu...atures.htm

I was considering one of these, but the consensus was that it would be more efficient to place a desuperheater on my AC unit and hook it to a Marathon electric tank.

Posted By Jelly on 04 May 2010 03:46 PM
I was considering one of these, but the consensus was that it would be more efficient to place a desuperheater on my AC unit and hook it to a Marathon electric tank.

Yes I agree that propobly the most efficient for the dollars, it is basically the same concept but uses its own coils to extract heat from the air.

I the late 80's before I was building with SIPs ,I put a heat exchanger on every home, for some reason got away from it ten years later

I looked at these early on but went with a traditional tank nat gas unit. All of the claimed energy savings are compared to a traditional electric water heater. When I started comparing numbers, a "regular" natural gas direct vent water heater cost less to operate than the heat pump heater. I think that the heat pump water heater could be a good fit for someone who is doing all electric and NOT doing geothermal. That was the only scenario I could see where it would make sense.

I just saw a heat pump water heater at my local hardware store. I'm intrigued. I once spoke to one of the guys at the Florida Solar Energy Center. He said newer AC units do not super heat anymore so using a heat exchanger is not as efficient as it used to be. He also said they were doing studies where a heat pump water heater was put up in the attic to help cool it as part of an energy efficient design.

So if I am not mistaken another benefit(cooling climates only) to a heat pump water heater is that it can help cool a home. I'll have to look up how many BTUs in cooling they put out.

Off the top of my head, placing a heat pump water heater in the hot attics of Florida sounds like a marriage made in heaven.  This assumes the water stays hot enough in the winter so freezing does not occur and the heat pump electronics can withstand the hot temps.  By the way, in my Auburn Alabama area, some builders place gas water heaters up on a platform near the ridge vent.  They claim this saves natural gas in the hot summer months.  I have not seen any side by side testing.  It does freeze in winter time here but so far I have not heard any horror stories.

Around here, electricity is heavily discounted if you accept an off hours or interruptible rate. So a heat pump water heater is considerably better than nat gas.

AC units still produce heat and it is still a good idea to capture this "free" heat for hot water.

I don't really think that it is an efficient water heater source, I'd rather go with the alternatives. It consumes a lot of energy based on my experience.

I'm taking a second look at the air source heat pump water heaters. We're all electric - no gas available. And I'm not finding anyone with the skill set to mount and maintain a desuperheater on my AC. So it looks like I might need to go with two smaller water heaters - one hybrid and one regular, because the hybrid probably can't handle tub-filling applications. Still working it all out. Electric tankless have their drawbacks too.