# Hybrid Electric water heater vs. indirect fossil fired



## SIERRADMAX (Mar 14, 2013)

Looking for some input.

My house uses a 40 gallon indirect water heater heated by an oil boiler. It's a well insulated water heater. I've kept track of oil consumption over the past 3 years and have noticed, on average, the indirect water heater uses roughly 25 gallons of oil a month with my household. At $3.69 a gallon, that is close to $100 a month.

My states electric providr has a rebate for the installation of a hybrid energy efficient electric water heater. Combined with a $300 Federal tax credit, this would nearly pay for the entire cost of the heater. I'm looking at the GE model or Kenmore.
http://www.sears.com/ge-geospring-50-gal-10-year-hybrid-electric/p-04232200000P
http://www.sears.com/kenmore-elite-...p-04232116000P?prdNo=5&blockNo=5&blockType=G5

Both estimate electrical usage of roughly 1900KWH. Does anyone know how Energy Star comes up with these values? How do they determine the household size and pair with the size (gallons) of water heater.

Our electric services has been slowly increaseing from $.14/kw to not $.157/kw in the last 2 years. At that cost, these new hybrid heaters should only cost $30-$40/month and even if it's consumption was 7,000kwh annually, it would still be less than what it costs me now to heat with oil.


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## pdf27 (Mar 14, 2013)

If you have an idea of your hot water consumption, it's fairly easy to calculate:
Energy use = water consumption x specific heat capacity of water x (hot water out temperature - cold water in temperature)

That is the raw amount of heat energy you use - multiply it by the efficiency of the proposed boiler (i.e. x1 for an electric resistance heater, x 0.5 for a 200% efficient heat pump, etc.) and that will give you your electricity consumption.


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## woodgeek (Mar 14, 2013)

The EF rating on the tank includes the effect of COP (generally 2-3 for a HPWH) and the effects of tank loss. It assumes a 'typical' usage that scales with the size of the tank. If you use less than a typical family, the EPA cost estimate will be too high, obviously.  The EF is the ratio of (electric) BTUs you buy to the BTUs you get out the tap. 

From a money point of view, the HPWH is a no brainer, esp if you have some nice rebates. I got $300 from my utility, but put in a 80 gal HPWH that was pricey. Even so, it is saving me $1000/yr relative to the oil system it replaced....$200/year to run versus closer to $1000 /yr for oil + $200 for boiler service.


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## Circus (Mar 14, 2013)

Do it. Not sold on Sears though. What you have now is the worst, especially when room heat isn't needed. Old boilers operate at about 180 degrees and waste most of the heat.


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## Gary_602z (Mar 15, 2013)

Cheap and easy way put in a 40 gal. electric. Cost may be 250.00 plus a little electrical work,put a heater blanket on it and it should run you 30-40 bucks a month. Probably good for 10-15 years. Rinse and repeat!

Gary


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## Bret Chase (Mar 15, 2013)

$100 a month for hot water? holy hell....  I have an oil HWH... I dump in 5 gallons every other week... and I have a family of 6.... 3 of them being tweens... smelly, smelly tweens...

I generally am not a fan of a super-stor setup for a number of reasons... the biggest one is it is a damned expensive way to make hot water...


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## maple1 (Mar 19, 2013)

This is a no-brainer especially with the rebates etc. you're talking about.

Get a HPWH, and get rid of the oil.

Haven't heard much about Kenmore, but the Geospring has happy owners on here.

Even putting in a regular electric hot water heater would put you way ahead of where you are now - one of those should do your hot water for not much more than $30/month. A HPWH should be less than that, and it will provide some dehumidification and A/C effect too.


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## semipro (Mar 19, 2013)

I have a GeoSpring and have had good luck with it.
You might also consider a Geyser unit if you can get the rebates on it. You may be able to use it with your existing tank.


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## woodgeek (Apr 12, 2013)

A note for tax day....if you installed a HPWH in 2012, you can get a tax credit for 10% of the cost (equipment + installation), up to $500.  I ended up getting $300 back on my 2012 taxes (plus the $300 rebate from my utility last year).

That and other energy improvement credits here...

https://www.energystar.gov/index.cfm?c=tax_credits.tx_index


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