AO Smith Voltex 80gal vs AO Smith Power Vent 75 Gas

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WildH

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Alright...I am wondering if any of you experts can answer my question because I have a boat load of conflicting data.

I live in Fargo ND. We are building a house and I am trying to decide between gas vs hybrid electric. It will be installed in a decent size mechanical room in the basement. Install cost for the gas is $2850 and the Hybrid is $2400. Gas is currently $1.18/therm and elec is .106/kwh. Family of 5 (three daughters...yes...I'm screwed).

What is more effecient and what would you suggest?

Lots of data out there, but I'm having a hard time finding anything convincing either way.

I've done a lot of research and my calculations show the hybrid is cheaper to run and cheaper to install (using energy.gov calculations) but others tell me different.

Thanks.

Tom
 

Reach4

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See http://www.erpud.com/comparison.htm

What website implies hybrid electric would be cheaper for you? Is it one of these? http://energy.gov/eere/femp/energy-and-cost-savings-calculators-energy-efficient-products ? I understand that at higher ambient temperatures that heat pumps are more efficient... but are they 300% efficient compared to resistance? It gets cold in Fargo. You would be using resistance heat a lot, I would think, unless you are using wells for heatpump water. And if you were using wells, your initial costs would be a lot more than what you are saying.
 

WildH

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Yes it does get cold in Fargo...conversly it get quite warm in the summer. :) It would be installed in a fairly large utility room in the basement of my home so realistically the ambient room temp would be fairly consistent at around 65 deg F.

I haven't found anything specifically comparing the two. Just a couple online calculators without a lot of clarification on input assumptions other than fuel cost and electricity cost. I went with this which is off of energy.gov website and inputted the EF ratings and rates at my local utility. Given the equations below I come up with:

Nat Gas Annual Operating Costs of $260/yr
Hybrid Elec Annual Operation Costs of $199.76

I'm just trying to get an idea of what people's real world experiences are. I just haven't seen any true comparisons of the two in controlled environments and wanted to see what everyone's thoughts were.

For gas and oil water heaters
You need to know the unit cost of fuel by Btu (British thermal unit) or therm. (1 therm = 100,000 Btu)
365 X 41045 ÷ EF X Fuel Cost (Btu) = estimated annual cost of operation
OR
365 X 0.4105 ÷ EF X Fuel Cost (therm) = estimated annual cost of operation
Example: A natural gas water heater with an EF of .57 and a fuel cost of $0.00000619/Btu
365 X 41045/.57 X $0.00000619 = $163
For electric water heaters, including heat pump units
You need to know or convert the unit cost of electricity by kilowatt-hour (kWh).
365 days/year x 12.03 kWh/day ÷ EF x Fuel Cost ($/kWh) = annual cost of operation
Example: A heat pump water heater with an EF of 2.0 and an electricity cost of $0.0842/kWh
365 X 12.03 ÷ 2.0 X $0.0842 = $185
The energy usage per day in the above equations is based on the DOE test procedure for hot water heaters, which assumes an incoming water temperature of 58°F, hot water temperature of 135°F, and total hot water production of 64.3 gallons per day, which is the average usage for a household size of three people.
 

Reach4

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Yes it does get cold in Fargo...conversly it get quite warm in the summer. :) It would be installed in a fairly large utility room in the basement of my home so realistically the ambient room temp would be fairly consistent at around 65 deg F.
The evaporator for the water heater is outside, or it at least is going to be using outside air, right? Otherwise it would cool your house down in the winter. So I am thinking that any calculations for heat pump stuff should have different figures for Fargo vs Florida. If they are not taking climate differences into account, they are missing a very big factor.

Example: A natural gas water heater with an EF of .57 and a fuel cost of $0.00000619/Btu
EF=.57 seems low. Doesn't that expensive gas unit that you are looking at offer better than that?

I don't speak from experience on these.
 
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