Is now the time to switch to an electric water heater?

[Kolesar]

There is going to be a significant shortfall of methane/natural-gas this winter as detailed in this article: Daniel Gross, Slate.com. We had been considering replacing our gas hot water tank with a quite more efficient on-demand gas heater. Our installer said that she had had a few problems with the earlier designs and I am not sure it makes sense altogether with respect to financial, cost of ownership, or environmental concerns. There are other alternatives such as installing an electric hot water tank with a timer or an electric on-demand heater. My idea of a seasonal solar pre-heater tank was nixed by her.

We need to eventually do something to replace the hot water heater. The chimney is unlined and since the furnace is now ducted through the wall, there is less draft and hence a long-term problem of condensation on the tile chimney liner.

Our usage is small: both of us commute all day and don't need water midday or after 9pm. The shower has a wand and I don't think it is low-flow. We have a contract for gas for <$10/million cu ft (I recall) but that will end next year. Electricity is a pricey $0.13/kilowatt*hour here. Our region is about 80%/20% coal/nuclear although we technically have a contract with Green Mountain Energy for a “greener” source.

I am sure my cheapest option is to drop in a new electric tank now or when the gas tank fails. We still have the wiring and timer from when the house had an electric tank in the 1980s. I could install it myself. I am just wondering if a case can be made for an on-demand heater using either fuel source. Both have significantly higher initial costs. The information at the gas and electric companies' websites is woefully short of good pricing data to evaluate the choices.

[ayeshahaqqiqa]

1. A couple of other options

some of my neighbors have solar powered hot water heaters (they are totally off the grid). Others have a wood burning hot water heater. We have propane, but with prices going up, I'm sure we'll opt for the solar powered heater whenever we can afford to go back to our home and not live in town(100 mile daily commute was eating us alive, and an apartment rents for less than my gasoline costs for a month-and that's with a fuel efficient car!)

[bemildred]

2. Whatever you do, it's wrong. nt

[kcwayne]

3. If your electric company uses oil fired burners you can expect the price

for KW consumption to rise significantly. If they use coal, you can still expect it to rise, they will make up some oil price related cost impact. If you are on nuke power, it will rise because they will say oil influenced inflation is raising their costs.

[ret5hd]

4. i can't directly answer your questions, but...

i will say that we have an on-demand electric water heater. we love it. it is about the size of a large phone book, which gave us a whole extra closet to use as a pantry.

on-demand electric water heaters are rated by temperature rise per gallons per minute. for example, ours is rated at 70 deg @ 2 gallons per minute...in other words, if the incoming water is at 40 deg (very very cold), it is capable of raising the temp of 2 gallons of water to 110 deg every minute.

a low flow shower head is metered to 2 gallons per minute. thus, even in the coldest regions, you couldd have a very comfortable shower.

one adjustment we had to make was on the clothes washer. when washing clothes in hot water, the valve would let much more than 2 gal per minute into the washer...so we just closed the hot water valve some.

downsides:
relatively expensive for the unit (about $500 if i remember)
wiring: a 220volt 100amp circuit was required

[Ready4Change]

5. Mix of pros and cons

Gas vs Electric: Gas prices will go up, no doubt. Depending on your local power sources, electric may or may not go up as well. Some electric plants are powered by natural gas, so you'd be paying extra either way. (It's also possible that you company will raise electric rates no matter what, citing a variety of excuses.

On Demand vs Tank: It's less efficient per gallon to quickly heat water on demand. However, storing more slowly, more efficently heated water in a tank results in losses over time. On Demand makes sense if you use very little hot water, or you use so much that your tank heater can't keep up anyway.

Objections to solar: Solar water heat got a bad reputation because many early installations were undersized, resulting in showers running cold half way through, etc... Experienced installers are better at estimating and meeting needs than they were. It can be so effective that many people use it to heat their homes, running pipes through the floors to radiate heat.

However, gotta pick your battles. If the SO is adamantly opposed to the idea of solar it may not be worth your marriage to force the issue.

[NNadir]

6. From a long term economic standpoint, coal and nuclear are

independent more or less of the fluid fossil fuel prices - if and only if - you are unfortunate enough to live in a coal producing region.

Right now in most places retail gas is still cheaper than retail electricity, although on the wholesale level this is not true.

From an environmental standpoint, if the majority of your power is being produced via fossil fuels than burning the transportable fossil fuel (natural gas) is better than burning the fuel at a power plant, since much of the thermal energy of the fuel at the powerplant is lost up the stack, through electrical resistance, and through carnot inefficiencies. Also you, and everyone else, has to breathe the shit from the powerplant. On the other hand the only loss you face with natural gas is the smaller fraction of what goes through your chimney. Thus the greenhouse gas impact is likely to be lower with the gas. Coal fired electricity is the most dangerous fuel commonly in use today.

It's not a good choice in either way, but if I were you, I would go with the gas.

I note that I have an electrical water heater in my own home, but 50% of the energy produced averaged of a year is produced by nuclear power in my state. Only 16% comes from coal. Actually on days of lower demand, the instanteous fraction supplied by nuclear is much higher, but in summer we tend to burn gas for our electricity here and the percentage owing to nuclear capacity is lower. (Our baseload is typically 50-60% of our peak load.) Thus my electric heater is safer and cleaner in winter than it is in summer.

[Strelnikov_]

7. Since The Furnace No Longer Uses The Chimney, I Would Go Electric

for the water heater. That way the chimney can be sealed.

That is my plan for when the gas furnace needs to be replaced. The way things are going, I will probably be looking at a geothermal system anyway.

[skids]

8. Go tankless gas. Keep the old tank.

...when upgrading to the tankless gas, have the plumber put in the
necessary guts for a solar preheat system. Then use the old tank to store preheated water from roof panels.

(Oh and on edit: point-of-use electric heaters can be good, if you only have a couple of sinks. They prevent the heat loss in pipes between the heater and faucet.)

[Kolesar]

9. I was thinking of depowering the gas fired tank

..with the idea of using it if the electricity fails in the winter. Then I could fire it up and have some source of heat in the house. The gas furnace won't run without electricity.

The house only has a kitchen, a bath, and a laundry. We could do it all with two point of use heaters. I was also debating if plastic plumbing for the hot water would make sense. Copper is a great heat conductor, and it would just suck the heat out of the flowing water in any on-demand heating system.

Great ideas, everybody, thanks!