Selecting a size of Hybrid Electric water heater


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Old 05-12-13, 10:17 AM
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Selecting a size of Hybrid Electric water heater

3300 sq/ft home + currently unfinished basement (that will be changing over the winter), '04 build, all electric home in central Ohio.

Currently have a builder grade 80 gallon hot water heater. Family of 3 and will likely stay that way.

Our current water heater is very inefficient and costing a fortune. It is also starting to show signs of a very slow death...taking longer to heat the water and occasional times where it doesn't fully heat the water. Time for a hybrid.

I've found 9 different brands to choose from: Rheem, GE, Kenmore, AO Smith, Whirlpool, Bosch, American, Reliance and Stiebel Eltron. Any to avoid?

Sizes range 50, 60, and 80 gallon. I know when our water heater was working at 100% that 80 gallons was overkill for our needs. The 50 and 60 gallon hybrid units seem to be a lot less expensive. Would it be okay to go with the smaller unit to same some cash or will I be unhappy with the result?
 
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Old 05-12-13, 12:26 PM
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Do you have a large tub that needs to be filled? Its code to have sufficient size heater for appliances.

Whats your electric rate?

IMO you may want to consider propane. Best IMO with this application would be tank less, even though I do not recommend them for other reasons.

How many baths?
 
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Old 05-13-13, 03:06 AM
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We have a Jacuzzi tub (big enough for 2) in the master bath that gets used maybe 2-3 times a year. There is also a bathtub/shower combo in the upstairs bathroom. When we give our two year old a bath we still utilize the baby bathtub inside it so I'm not filling a tub.

I have tracked electric use for the past couple of years. Though the rate changes monthly, the out the door rate (after taxes and their other BS fees) averages about $.103 per KwH. We also average around 2800 KwH per month. It has been high as 6000 in a month and as low as 1000 (though that was in the fall of 2010 and never to be seen again, now the lowest is around 2000). My monthly bill averages to $276 though I've seen single months of over $500 in the winter (yes, I have a heat pump).

Propane is not an option I will consider. Propane is expensive here and even if there was a small cost savings, the ROI would be way too long to consider it. I don't have a great place to hide a tank, so either I have a big ugly tank in the yard or I have to have it buried (expensive).

Tankless only works here with natural gas or propane. No natural gas in our neighborhood and electrics can't handle our cold ground water.
 
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Old 05-13-13, 06:24 AM
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Hi Nitro,
I've added a link at the bottom with lots of good information.
Note the "How much will I save?" topic at the end. At your $0.10 per kwh their estimate would put you at a potential savings of $25 to $150 (their $40 to $270 @ $0.17/kwh adjusted for your $0.10/kwh) per year and that does not include the scavenged heat from your finished and fully heated basement. When a HP is stealing heat from mother nature in a warm climate and providing the home owner with cooling and dehumidification they are a win/win. But when they have to rob your home's heating system, even though yours is an efficient heat pump source, they struggle to provide a meaningful improvement. Heat from your whole house HP at an EF rating of 2 that is then recovered by your HPWH at the same EF of 2 results is an overall EF of 1. You paid twice for the same heat.

I have measured the power consumption on several regular electric water heaters and each time I found it was no where near what I or the home owners expected. At my own house at 17 cents per kwh with 5 adults I averaged $35 a month. I never found the water heater to be the smoking gun for high electric bills.

The better approach is to reduce your hot water use. Low flow shower heads were a big improvement for us. Plus, our two girls growing up and out on their own.

Heat-Pump Water Heaters Come of Age | GreenBuildingAdvisor.com

Bud
 
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Old 05-13-13, 07:03 AM
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After your additionall info IMO I would install two 40 gallon electric hot water heaters in parrallel. Pipe in a way that you will only use one heater with proper shut offs to isolate either heater.

When you want to fill the big tub put the other heater on line.

This will allow you to use a 40 gallon for everyday use, but have the option of an additional 40 gal for the tub fill.

Also you can alternate between the two heaters on a 6 month interval. It will allow you to even thier usage and flush the heaters when doing so.


See if ohio has any type programs that add a second meter for your heaters that will reduce the rate at certain times. Also check for income levels as you can get assistance from heap/leap and such that will give you $ off every month and or a one time payment every year.

Electric Consumer Information - PUCO

That would be your best payback.

Lower the temp on the heaters to 120f.....

Last your payback may not be good, you would need to calculate, but you can cut the bill down in the summer months by going solar... They have some turn key systems out there. Just a though but they do run about $4k without install.

I like ao smith products. I install and use them in my own home.

Cirrex® Solar Electric System - Water Heaters Residential by A. O. Smith > A. O. Smith Water Heaters
 
 

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