It all depends-----

My propane cost hit $3.10/gal in Dec., kwh is $.12. Propane is MORE expensive per btu at $2.70+/gal, even if you have 100% efficiant use.

There are 2 adults here, low DHW use. I have a 50gal elec. with a 8 event digital timer. It is on 2 hrs max a day@ 4.5kw, occasionally more in winter, less in summer. Less than $30/mo AVERAGE.

My summer (no heat) electric bills are under $40, average.

A moderate 50 gal + timer is $3-400, lasts 10+ years. Have done it this way for 20+ yrs.

Unless you have cheap-cheap nat gas, there is no cheaper way to heat water from the grid.

Follow up on the GE Hybrid, installed two days ago. (Yes...Propane is too expensive! And when you factor in the trucks that carry it around to fill our tanks, it gets less and less green.) The GE Hybrid installed easily. After two days, the pattern seems to be that it runs in e heat (heat pump) twice a day; once just to warm up which takes from one half to one hour. And again in the evening after we've washed dishes and taken two showers (it starts up about the time the second shower begins). It takes about 2 hours of run time in heat pump mode to recoup heat again after that. It is louder than what I had hoped, but its in the basement so its not a problem. Compared to purchasing a new regular propane hot water tank, and considering the fed tax credits, and the cost of fuel for each, the hybrid comes out ahead in under 3 years, by our estimates.

Posted By Dana1 on 26 Feb 2010 12:26 PM

Posted By jonr on 25 Feb 2010 07:04 PM
As Brock experienced, a heat pump water heater certainly does not add net cooling load (aka heat) to the interior space - quite the opposite. It's doing the same thing as a geo heat pump in cooling mode - except that the heat is going into a hot water tank instead of your yard (or some combination of your yard and your hot water tank if you use a desuperheater).

 Unless it adds 100% of it's compressor heat to the water (which it can't), it DOES add heat to the interior space. This load is much less than the heat it's extracting from the room and pumping into the water, but the heat pump would have to remain below room temp to not put some heat into conditioned space.

But it's a small load, to be sure-could even be less than the heating up of the wires to the tank from the current.  But a small net positive is radically different from a small net-negative, eh?

Our geo unit is in our basement right next to the pre water heater, in the cooling season the geo heat pump is a lot bigger and has more AC motors running. The heat from the geo unit and its associated pumps are also in the same conditioned space so I am still confused on how you could be gaining more heat with a air source unit compared to a ground source unit? I am not saying the air source unit is more efficient, but both units "leak" the motor heat to the conditioned space, don't they?

Yes. During the cooling system, both are doing the same thing in the same way - extracting heat from the air and moving it into geothermally cooled water. And in both cases, the amount of net cooling is quite substantial - the COP is high enough that some of the fairly minimal motor winding heat* being released to the air isn't a big issue.

* note that a motor drawing 1000 watts has only ~200 watts of internal losses that cause heating.

From news reports I've heard, heat pump hot water heaters may qualify for a 50% instant refund when Obama's Homestar jobs bill gets passed.
That together with the 30% tax credit is going to make this a very popular option. Does anyone else understand that program that way ?

Yes, It sure looks like they're thinking about green energy again in the Homestar program. I wonder if they are going to date it part way through the year, though, so early year purchase might not count ? On the other hand, the Homestar program was initially introduced in the fall of 2009, so maybe it might cover all of 2010. Time to Stay Tuned!!