# Energy Efficient Electric Water Heaters



## charly (Nov 18, 2010)

Any pro's or con's on the GE Geospring or AO Smith Voltex electric water heaters. My farm house basement is unheated. This units require a minimum of 45 degrees to keep working. I figure the basement should stay at 50 over the winter. A friend said he had to blow heat down into his basement that it got so cool from the heat pump removing the heat from the cellar air. Anyone else experience anything like that? Don't want to get this and find out my basement is freezing up. Also is the Voltex worth the extra 600 dollars. Your getting 80 gallons of water with the Voltex verses 50 with the GE.


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## midwestcoast (Nov 18, 2010)

Don't have one. Couple threads on here if you haven't read them. If you're basement is below 45, you've got bigger problems?
Extra 30 gals is only worth anything if you need a tank that size. Smallest that will suit your needs is the best choice IMO, keeping in mind it may have a slower recovery rate.

https://www.hearth.com/econtent/index.php/forums/viewthread/57640/
https://www.hearth.com/econtent/index.php/forums/viewthread/59281/


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## charly (Nov 18, 2010)

midwestcoast said:
			
		

> Don't have one. Couple threads on here if you haven't read them. If you're basement is below 45, you've got bigger problems?
> Extra 30 gals is only worth anything if you need a tank that size. Smallest that will suit your needs is the best choice IMO, keeping in mind it may have a slower recovery rate.
> 
> https://www.hearth.com/econtent/index.php/forums/viewthread/57640/
> https://www.hearth.com/econtent/index.php/forums/viewthread/59281/


Thanks, I'll check out the other threads.


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## Later (Nov 18, 2010)

I would expect that the heat pump units would have a "shutdown" system to switch to 100% resistance heat in the event the ambient temp got too low. Then you would have a traditional electric heater.


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## charly (Nov 19, 2010)

Retired Guy said:
			
		

> I would expect that the heat pump units would have a "shutdown" system to switch to 100% resistance heat in the event the ambient temp got too low. Then you would have a traditional electric heater.


Yes I read that they will do exactly as you say.


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## Later (Nov 19, 2010)

So, for about 8 months a year you'd save. I have been looking at electric resistance heaters for our seasonal home and see that the $300 ones have virtually the same specs as the $500 ones. Given the life of water heaters, our usage and my age, I don't think I could recoup the added cost of the HP units in my lifetime.


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## jebatty (Nov 21, 2010)

The easiest and most cost effective thing you can do with an electric hot water heater is to do a few simple things and possibly achieve a 50% reduction in KWH use, as we did: Electric Hot Water Heater

There is 6" of fiberglass insulation under the foil bubble wrap.


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## karl0525 (Nov 21, 2010)

I have the GE one that i got with the texas appliance rebate. Took 300 bucks off the price and then getting 30-percent back from uncle sam.And oh ya i used the 10 percent coupon from lowes also.I can say iam pleased with the unit as it is installed inside and overall is not that noisy.we put it in standered mode in winter so it wont use the heat from the house but love that it helps out with the ac in the winter.i seen a 20 dollar diffrence in our first light bill and looking over the 1 year history of electrical bills it has saved about that every month, would do it all over agian in a heart beat.


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## jebatty (Nov 22, 2010)

Our 1500 sq ft house, plus full basement, is 100% electric (except wood stove for heat): includes electric cooktop and oven, electric clothes washer and dryer, dishwasher, refrigerator, freezer, all the typical other electric uses, etc., and of course electric hot water heater. Just my wife and I, plus children and grandchildren guests from time to time. Our total electric bill averages $75/mo, of which just $5/month is electric hot water (on a separate meter, so I can positively track electric hot water usage). I can only wonder about the amount of hot water we would have to use to realize a $20/month savings on electric hot water by getting a more efficient electric hot water heater. 

When our electric hot water heater kicks the bucket, I will replace it with the cheapest electric hot water I can find and then insulate to the bejezus. Resistance hot water elements are nearly 100% efficient, so I can't see how a heat pump based hot water heater can be more efficient than 100%.


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## DBoon (Nov 24, 2010)

Hi jebatty - great house you have there, I've always enjoyed reading all your posts.  

You are pretty lucky with a 4 cents/kWh overnight right.  Most of use don't have it that cheap overnight.  My overnight rate is 11 cents/kWh (used to be 8) and my day rate is 15 cents/kWh.  In general, the utility is slowly closing the gap between day and night rates.  I would imagine five years from now there will be no overnight rate anymore.  I think their generation and demand mix is such that they don't have surplus plants running at night that cost more to shut down than keep running. 

In any case, with triple or quadruple the electric rate, less conservation, or more people, things change pretty quickly.  My wife and I probably use a little more hot water than you, but not much.  But we would pay $20 total for that every month.  Heat pump water heaters are just starting to make sense at that usage (though the payback may be the entire lifetime of the unit).  I bought mine just because 1) I run a dehumidifier in my basement anyways, and I will get that for free when the heat pump water heater runs, and 2) I am on a personal quest to reduce my electric usage as much as possible (for a variety of reasons). 

The heat pump water heaters uses an electric motor to drive a reverse refrigeration cycle that moves heat from the room to the water tank.  For a reasonably "warm" (50 degrees F or so) room, there is enough heat to make the process efficient enough to transfer 2 BTUs worth of heat from the room for 1 BTU worth of electricity consumed by the pump.  That is high the efficiency can be 200% (although this does seem counterintuitive, I agree).


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## Highbeam (Nov 24, 2010)

Yes, the whole concept of heat pumps is that they can be more than 100% efficient by stealing energy from the air. So you add electric energy from the meter to the heat energy stolen from the environment to get a total amount of heated water. 200% is easy, look at home heating systems with heat pumps or geothermal. You don't need to bring all the energy to your house through the powerlines.


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## jebatty (Nov 24, 2010)

Some quick research said you're correct, efficiency over resistance hot water heaters (1 being resistance) is 2-3, so 2 to 3 times more hot water for the same amount of electricity. You all also have it right to locate them in areas that normally are too warm and need cooling and/or dehumidification, 40-90F being the recommended ambient temperature of the units in the info I saw.

If you can realize a savings of 50% or more, then be sure also insulate the unit as appropriate and all accessible hot water lines for some substantial additional savings for even more bang for the buck. Insulation is low buck, high return on investment.


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## semipro (Dec 6, 2010)

One of my 25 year-old water heaters finally gave out.  I could no longer remove key parts like heating elements and anode rods.  I replaced it with one of these: http://www.geappliances.com/heat-pump-hot-water-heater/  It was on sale at Lowes and is eligible for a 30% federal tax rebate.  Its does cool our basement but should be set up to (indirectly) take advantage of our ground-source heat pump since that heats the air inside the house.  It does cool and dehumidify the basement utility room I installed it in which should be good in the summer too.  Maybe I won’t have to keep using my dehumidifier.  When operating the fan is about as loud as a small computer server.  We have hard water which has really been hard on our electric water heaters.  The lime collects on the heating elements and then falls off, collecting in the bottom of the tank.  I'm hoping this heater won't have that problem since the heating coil is on the outside of the metal tank. We plan to operate it in the highest efficiency mode so that the aux. heating elements won't engage.  It might cause my teenagers to get out of the shower a little sooner   After only a day's use I"m impressed.  Its not that loud and it seems to heat the water up pretty fast.


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## semipro (Dec 6, 2010)

jebatty said:
			
		

> The easiest and most cost effective thing you can do with an electric hot water heater is to do a few simple things and possibly achieve a 50% reduction in KWH use, as we did: Electric Hot Water Heater
> 
> There is 6" of fiberglass insulation under the foil bubble wrap.



I'm glad you reminded me.  When installing our Geospring i put it on top of a foam insulation pad.  I also created heat traps with flexible stainless tubing and plan to insulate the piping.

Edit: I'm considering adding some additional insulation around the tank but plan to check temps with an IR gun first to see how much heat we're really losing that way.


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## Mcbride (Dec 9, 2010)

Look at the Marathon brand.
Much better made and insulated than the regular water heaters.


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## SolarAndWood (Jan 16, 2011)

Semipro said:
			
		

> After only a day's use I"m impressed.  Its not that loud and it seems to heat the water up pretty fast.



Still impressed a month later?  What did you end up doing with the insulation?  I have a 15 year old lp unit that I am feeding with $3.50/gal grill tanks now that the big tank is gone.  Looked at the tankless, but they seem to draw a lot of juice for the heat they produce.


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## GaryGary (Jan 17, 2011)

Hi,
The heat pump water heaters do remove heat from the area they are in, so that area will get colder.  
The colder the area the HP water heater is in gets, the lower the efficiency of the heat pump will be.

If the area the water pump is in is part of the conditioned space in the house, then the heat that the HP water heater gets for "free" might end up just having to be provided by the furnace -- not such a fine deal.  But, sounds like it might not apply in your case.
On the other side of the coin, in the summer, the HP water heater can provide a bit of free AC if you have a way to duct the cool air to where its needed.

Some interesting stuff on heat pump water heaters here:
http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm#HeatPumpWater Heater

The one called "winter use of heat pump water heater" gives a way of basically changing where the air that the heat pump water heater uses as a heat source on a seasonal basis so that you get more benefit out of the heat pump.

Thought about a tankless NG, or a solar?

Gary


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## SolarAndWood (Jan 17, 2011)

Thanks for the thoughts Gary.  No natural gas here.  I have 1000 sq ft of 7/12 solar south roof ready for some combo of solar water and PV eventually.  Just looking for a stopgap until I get a bunch of other stuff done.  It will reside in the space the stove is in.  So, hot air from wood in the winter and air conditioning where I need it in the summer anyway.


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## semipro (Jan 17, 2011)

SolarAndWood said:
			
		

> Semipro said:
> 
> 
> 
> ...



Yes.  Still impressed.  I don't have energy usage statistics though; too many other variables confounding the info.  

I can't wait until summer when it should really do well and hope we no longer need a dehumidifier in the basement.  Solar preheating is the next step. 

I placed it on top of 2" of polyiso foam.  I used my IR gun to check the water heater's outer skin temp and compared it to that of surrounding surfaces of non heat generating surfaces.  There was only a several degrees difference so I haven't put a high priority on adding any additional insulation.


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## SolarAndWood (Jan 17, 2011)

Cool, thanks.  I think I am going to do a simple pre-heat system as well when there is no risk of freezing.


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