Which is more economical - electric or natural gas water heater?

[Some Guy]

When all taxes and other charges are factored in, I pay:

10.62 cents per kWh for electricity

50.46 cents per cubic meter (1.43 cents per cubic foot) for natural
gas.

These are in CDN dollars (which is irrelevant since I am quoting both
forms of energy with the same currency but in case you're interested
the conversion between USA/CAN is about 1.16 CDN per 1 USD).

Given the above costs, what will be a more economical hot water heater
- electric or gas? (This is assuming I buy a tank, not rent it from
my local utility, and this also is just looking at the monthly energy
consumption of the tank - not the initial cost to purchase and
install).

I assume that both types will be equal when it comes to insulation (or
rate of heat loss) but perhaps not identical when it comes to
potential for problems (since a gas heater needs a void or space
running through the center, which means it has a more complex
contruction, as a pressure-vessel there are more seams that can
ruputure or leak).

I notice that new electric hot water tanks are almost half the cost of
a similar-sized NG tank (ie advantage=electric on initial purchase
price). An electric tank is also more "controllable" - I can more
easily control it in terms of powering it for time-of-day and
day-of-week operation.

So I think conceptually that electric hot water tanks are a better way
to go. But for long-term energy usage assuming the costs quoted above
(or more importantly their ratio) holds into the future - which type
will be cheaper to run?

 

[.p.jm@see_my_sig_for_address.com]

When all taxes and other charges are factored in, I pay:

Kee-rist.

You have to spam this bullshit all over the fucking Internet ?

Just in order to avoid doing YOUR OWN FUCKING HOMEWORK ????

Keep this fucking bullshit out of alt.hvac !!!!


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[John Weiss]

When all taxes and other charges are factored in, I pay:

10.62 cents per kWh for electricity

50.46 cents per cubic meter (1.43 cents per cubic foot) for natural
gas.

Given the above costs, what will be a more economical hot water heater
- electric or gas? (This is assuming I buy a tank, not rent it from
my local utility, and this also is just looking at the monthly energy
consumption of the tank - not the initial cost to purchase and
install).

I find that 1 kWh = 3,413 Btu (http://www.baywinds.com/new/FossilFuel.html).

Also, 1 Therm = 100,000 Btu.

And 1 Cubic foot of natural gas = 1,020 Btu (approx)
(http://www.energy.rochester.edu/units/conversions.pdf).

So, 1 CuFt of NatGas = 1020 BTU / (3413 BTU/KWH) = 0.3 KWH.

You pay 1.43 cents / 0.3 KWH for gas = 4.78 cents/KWH.

Natural gas is 45% the cost of electricity.

Now figure out how many KWH you use to figure out the payback time for a more
expensive gas heater.

 

[John A. Weeks III]

When all taxes and other charges are factored in, I pay:

10.62 cents per kWh for electricity

50.46 cents per cubic meter (1.43 cents per cubic foot) for natural
gas.

South of the border here in Minnesota, we have off-peak power
available to us. For any device that can be cycled off during
peak times, or can be rescheduled until night, we get a huge
discount. The way to take advantage of this is to use an
electric storage water heater. These are larger tank units
with a huge amount of very efficient insulation. The idea is
that you heat the water at night, and it keeps warm all day
as you use it.

-john-

 

[Vaughn]

Crossposters are right down there on the evolutionary scale with spammers.

Vaughn

 

[daestrom]

When all taxes and other charges are factored in, I pay:

10.62 cents per kWh for electricity

50.46 cents per cubic meter (1.43 cents per cubic foot) for natural
gas.

These are in CDN dollars (which is irrelevant since I am quoting both
forms of energy with the same currency but in case you're interested
the conversion between USA/CAN is about 1.16 CDN per 1 USD).

Given the above costs, what will be a more economical hot water heater
- electric or gas? (This is assuming I buy a tank, not rent it from
my local utility, and this also is just looking at the monthly energy
consumption of the tank - not the initial cost to purchase and
install).

I assume that both types will be equal when it comes to insulation (or
rate of heat loss) but perhaps not identical when it comes to
potential for problems (since a gas heater needs a void or space
running through the center, which means it has a more complex
contruction, as a pressure-vessel there are more seams that can
ruputure or leak).

I notice that new electric hot water tanks are almost half the cost of
a similar-sized NG tank (ie advantage=electric on initial purchase
price). An electric tank is also more "controllable" - I can more
easily control it in terms of powering it for time-of-day and
day-of-week operation.

So I think conceptually that electric hot water tanks are a better way
to go. But for long-term energy usage assuming the costs quoted above
(or more importantly their ratio) holds into the future - which type
will be cheaper to run?

Everyone has posted some good information for you so far (save one).

I'll just add that there are a couple of more factors to think about.

A natural draft gas heater (one that uses a chimney) can operate just fine
even without electricity in case the power goes out.

A forced draft gas heater (one that vents thru the wall and has a blower)
needs electricity to run at all. But you can plug them into a cheap 120V
'lamp timer' to 'program' it to run only when you want.

But programming won't really cut down on your losses unless you're gone for
several days, in which case you could just shut it off (or turn to 'pilot'
only to save having to relight the pilot when you return). The one
exception is if you have TOU (time of use) electric like John from Minnesota
has, where the cost of running it at night is a great savings.

Because gas heaters have a fire tube that runs up through the middle, they
have more standby losses than electric.

Insulate the vertical piping right above the heater (both the hot and cold)
to help reduce losses by convection when no water is being drawn off.

Consider getting a waste-water heat recovery heat exchanger to avoid sending
all the energy 'down the drain' after use. (google 'GFX heat exchanger' for
an example)

daestrom

 

[Bill]

If there is just one person in the house...

Electric can be less expensive if you get a "time of use" electric meter
from the electric company and a water heater timer (link below), then run in
the early morning (off-peak time) for about 40 minutes - just long enough
for one shower, then you will have warm (not hot) water for the rest of the
day with the water heater not running. So the water heater is only running
40 minutes a day. You can also skip taking a shower on some days (maybe a
weekend day) and just run the water heater for 15 minutes and this will give
you warm water for most of the day.

If you have more than one person in the house, I suppose you could get a
couple of water heaters and run them both in the early morning (off-peak)
and use one, then switch to the other.

Water heater timer...
http://www.rewci.com/inehwaheti24.html

 

[Canfree]

When all taxes and other charges are factored in, I pay:

10.62 cents per kWh for electricity

50.46 cents per cubic meter (1.43 cents per cubic foot) for natural
gas.

These are in CDN dollars (which is irrelevant since I am quoting both
forms of energy with the same currency but in case you're interested
the conversion between USA/CAN is about 1.16 CDN per 1 USD).

Given the above costs, what will be a more economical hot water heater
- electric or gas? (This is assuming I buy a tank, not rent it from
my local utility, and this also is just looking at the monthly energy
consumption of the tank - not the initial cost to purchase and
install).

I assume that both types will be equal when it comes to insulation (or
rate of heat loss) but perhaps not identical when it comes to
potential for problems (since a gas heater needs a void or space
running through the center, which means it has a more complex
contruction, as a pressure-vessel there are more seams that can
ruputure or leak).

I notice that new electric hot water tanks are almost half the cost of
a similar-sized NG tank (ie advantage=electric on initial purchase
price). An electric tank is also more "controllable" - I can more
easily control it in terms of powering it for time-of-day and
day-of-week operation.

So I think conceptually that electric hot water tanks are a better way
to go. But for long-term energy usage assuming the costs quoted above
(or more importantly their ratio) holds into the future - which type
will be cheaper to run?

 

[Canfree]

I find that 1 kWh = 3,413 Btu (http://www.baywinds.com/new/FossilFuel.html).

Also, 1 Therm = 100,000 Btu.

And 1 Cubic foot of natural gas = 1,020 Btu (approx)
(http://www.energy.rochester.edu/units/conversions.pdf).

So, 1 CuFt of NatGas = 1020 BTU / (3413 BTU/KWH) = 0.3 KWH.

You pay 1.43 cents / 0.3 KWH for gas = 4.78 cents/KWH.

Natural gas is 45% the cost of electricity.

Now figure out how many KWH you use to figure out the payback time for a more
expensive gas heater.

Yes but the efficiency of electric is 100% . What about gas ?

 

[Canfree]

Yes but the efficiency of electric is 100%. What about gas?

Sorry about my previous message

 

[Noon-Air]

Yes but the efficiency of electric is 100% . What about gas ?

100% efficient?? LOL

average water heater operating cost in this area is roughly $30/mo on
electric, and less than $10 on natural gas.

 

[Oscar_Lives]

Typical is about 85%

Even with that big hole sucking warm air to the outside 24/7 (flue)?

 

[John Weiss]

Yes but the efficiency of electric is 100% . What about gas ?

Start at http://www.aceee.org/consumerguide/topfurn.htm or
http://www.cmhc-schl.gc.ca/en/burema/gesein/abhose/ce_048.cfm (in Canada).

New gas furnace designs are 90%+ efficient -- some as high as 96%. So, even at
the low end of the high-efficiency range, gas cost is still 50% of electricity.

Back to his payback calculations...

 

[daestrom]

Yes, and electricity efficiency is probably closer to 25%, even without
the flue. A LOT of energy is wasted in the conversion from electrical
energy to heat energy.

What planet are you from?? An electric heater is *very* efficient from a
thermodynamic standpoint in creating heat. Where does your 'lot of energy'
go, if not into some form of heat? Put in 10 kwh, and 10kwh of heat are
generated. Now, you have to put in a lot more raw fossil fuel at the
electric plant to *get* 10 kwh, but that's a different matter altogether.
And since electricity costs more per kwh an equivalent amount of NG, it is
an *expensive* way to generate heat.

However, when you convert natural gas to heat, you only waste a little bit
of energy in the form of light. -Dave

And that 'light' just warms up the combustion chamber (except for the tiny
bit that escapes out the 'peep' hole). NG waste some energy by letting hot
CO2 and water vapor go up the flue though. So they are less efficient than
electric heaters. But NG is usually a *cheaper* source of energy if all you
want is heat.

daestrom

 

[Bill]

Doesn't that maximize the amount of thermal variation in the tank, and
thus stress it, shortening its life?

I've had my water heater on a timer for years and have not had any problems.
And I have saved a ton of money over those years considering an electric
water heater can be 1/3 of an electric bill.

 

[Geoman^^]

DON"DON'T RESPOND TO THIS IDIOT WHO CROSS POSTS

 

[Bob Pietrangelo]

I know they're expensive, but have you considered an "on-demand"
natural gas hot water system? The initial cost is high, but the
payback is supposed to be quite substantial since you're not heating
water for nothing while you're not using it.

On-demand water heaters do not produce enough water for multiple showers,
especially in the winter. They also are more prone to mineral build-up in
the coils. I do not recommend them for anything more than a small
apartment.

 

[John Gilmer]

Sure electric is 100% efficient for water heating, but it costs more to
operate, making gas the winner.

Actually, electric water heating isn't 100% efficient. The difference is
that the "waste" heat with electric heating stays in the house. With gas,
most of the waste heat goes up the stack.

And there are other considerations. For example, it's practical to place a
small electric water heater relatively close to the point of use for things
like basins.

The other major consideration is whether you have gas coming into the house
in the first place. If you use gas for heating and cooking and water
heating then it would almost always pay to stay with gas. If you only
use gas for hot water and everything else is electric you may well be better
off going all electric. We found that when we moved from a house with gas
heat and hot water but electric stove and air conditioner to a truly all
electric house (with deep well), our utility costs were about the same and
the new house was quite a bit larger.

 

[SQLit]

On-demand water heaters do not produce enough water for multiple showers,
especially in the winter. They also are more prone to mineral build-up in
the coils. I do not recommend them for anything more than a small
apartment.

The total degree temp increase with colder input water was the turn off for
me. Reading the specs of the various manufactures was confusing at first
then it all made sense. That and in a city of over a million people there
were no spare parts available.

 

[John P.. Bengi]

The Rinnai units are up to 199,000 BTU and can give 5
GPM at 70F rise.

How hot do you need your two simultaneous showers? I
doubt you shower at over 110F.