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The humble water heater could be the savior of our energy infrastructure woes

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Re: The humble water heater could be the savior of our energy infrastructure woes

#51

Post by coryrc »

cartoonworld wrote: post #4
ttyprintk wrote: post #2

I think these water heaters in question are actually hybrid units. They cool the surrounding room to maintain a temperature set point. In some places, colder room air and thus more condensation is not appreciated. A less-sophisticated approach is to put your tank heater on a timer. Think carefully before you do this. Does your tank heater have the capacity to keep the water hot for a full shower, until you’re back un…

>A less-sophisticated approach is to put your tank heater on a timer. Think carefully before you do this. Do not do this without understanding the lifecycle of legionella pneumophila, or you will face a dramatic decrease in your quality of life. https://en.wikipedia.org/wiki/Legionnaires'_disease

Man, let me tell you about my friend the Greeks. Any time they leave the house, turn off the water heater. Hotel: water heater is off until you ask. All because in the 50s (iirc) they incorrectly installed a bunch of heaters which exploded from overpressure. I'd be surprised if they have unusually high rates of Legionnaires'.

Re: The humble water heater could be the savior of our energy infrastructure woes

#52

Post by selectodude »

elil17 wrote: post #45

Another type for thermal battery: ice thermal storage. Instead of running AC, it’s a freezer that makes ice during the night (using off-peak electricity and taking advantage of the cooler nighttime air) and then melts it during the day to cool large buildings. They’re a ridiculously good idea if you’re running a large enough HVAC system - they can even lower capital costs compared to traditional systems. Unfortunatel…

There is a large building in Chicago that basically contains a giant ice cube.

https://www.enwave.com/locations/chicago.htm

Re: The humble water heater could be the savior of our energy infrastructure woes

#53

Post by coryrc »

coryrc wrote: post #46
deviledeggs wrote: post #42

Earlier quoted context omitted.

Heat pump water heaters mentioned in the article are better for efficiency. They typically use half the energy of a normal water heater. And they cool the air around them, so if you live in a hot area they save more.

And if you live in a cold area, you get no efficiency advantage, pay more, and probably eventually leak coolant with a GWP of 2088.

A system like Sanden CO2 or Chiltrix will heat your water with outside heat, so it's always 2x+ the efficiency of resistance heat. If your climate is predominately hot then thermal collectors are far more efficient, but interior hot water heat pumps would be an okay choice where that's not possible.

Re: The humble water heater could be the savior of our energy infrastructure woes

#54

Post by labster »

vl wrote: post #15
labster wrote: post #7

Earlier quoted context omitted.

Large tanks are cheap, square feet of residential space are expensive. Tankless water heaters work well when powered by nat gas, but if you want electric it’s not great. I’ve been intending to do solar water heating, and convert from gas to electric, but the old heater gave out at the wrong time. So the current plan is build the solar and make a new place to move the electric tank into, then use the other tank for ex…

> The good news about climate change is that I never have to worry about the pipes freezing any more. As they recently learned in Texas.

Nah, I’m in coastal California. The last frost here was in the 1990s, last time it snowed was the 1930s. Think I’ll be okay.

Re: The humble water heater could be the savior of our energy infrastructure woes

#55

Post by aaron695 »

WhompingWindows wrote: post #28
s0rce wrote: post #18

Virtual battery, there is an interesting project to do a similar thing with aluminum smelters where you heat them and operate at full capacity off-peak and then during peak electricity usage you run slower. Since a smelter consumes so much power this can significantly level the grid usage.

Would that be economical? Places with abundant geothermal power like Iceland are probably going to make much cheaper aluminum smelting than anywhere else.

Iceland's power is hydro. (It's only ~26% geothermal)

The Aluminum smelting is done on hydro not geothermal.

Iceland is small compared to the USA or Indonesia for geothermal power. Large per capita, but Mexico has more geothermal power.

https://www.thinkgeoenergy.com/the-top-10-geothermal-countri...

(Iceland also has geothermal heating for housing which works well)

Re: The humble water heater could be the savior of our energy infrastructure woes

#56

Post by jhgb »

toomuchtodo wrote: post #48
jhgb wrote: post #43

Earlier quoted context omitted.

> timer or grid controlled water heaters are old and busted (especially with bacteria concerns due to a lack of in tank convection) This is literally the first time I'm hearing of this as a concern. Our local recommendations are to keep tank temperature above 70C and you should be fine.

https://patents.justia.com/patent/20180290899 provides background on the topic. Keeping your hot water tank at or above 50-55C constantly is a reasonable mitigation, anything hotter can cause scalding.

You can't scald yourself with mixed water from the faucet unless you set the faucet lever wrong, so I've never had that issue. In addition to that, the recommended high temperature setting (I believe the recommended default setting on my tank is 60 C?) increases the amount of mixed water that you can use before depleting the tank, so even a smaller tank suffices for a person.

Re: The humble water heater could be the savior of our energy infrastructure woes

#57

Post by cartoonworld »

coryrc wrote: post #51
cartoonworld wrote: post #4

Earlier quoted context omitted.

>A less-sophisticated approach is to put your tank heater on a timer. Think carefully before you do this. Do not do this without understanding the lifecycle of legionella pneumophila, or you will face a dramatic decrease in your quality of life. https://en.wikipedia.org/wiki/Legionnaires'_disease

Man, let me tell you about my friend the Greeks. Any time they leave the house, turn off the water heater. Hotel: water heater is off until you ask. All because in the 50s (iirc) they incorrectly installed a bunch of heaters which exploded from overpressure. I'd be surprised if they have unusually high rates of Legionnaires'.

A quick google proves your intuition pretty spot on. Looks like there was a major increase of the disease between 2016-2018.

Greek public health announcement regarding outbreaks ~2018: https://www.acg.edu/about-acg/institute-of-public-health/fac...

An anecdotal account of a man contracting Legionnaire's while on holiday in Greek apartment: https://www.irwinmitchell.com/news-and-insights/newsandmedia...

An older account of a similar ocurrance in a hotel, just as you describe: https://www.sciencedirect.com/science/article/abs/pii/004313...

Granted, no mention of this particular cultural artifact. Global temperature warming was cited in some reports as part of the cause of these outbreaks. It seems that the bacteria really likes to live in showerheads, so especially older shower heads can accumulate legionella especially given commonly lukewarm temperatures. This creates a perfect storm of ideal reservoirs, protected, moist, temperature conditions and aerosolized distribution.

Nasty.

Re: The humble water heater could be the savior of our energy infrastructure woes

#58

Post by perihelions »

Can you also store cold cheaply? For example, to run an A/C early in the morning, and put the cold in an insulated tank of a room-temperature phase change material [0]?

[0] https://en.wikipedia.org/wiki/Phase-change_material#Common_P...

Re: The humble water heater could be the savior of our energy infrastructure woes

#59

Post by s0rce »

WhompingWindows wrote: post #28
s0rce wrote: post #18

Virtual battery, there is an interesting project to do a similar thing with aluminum smelters where you heat them and operate at full capacity off-peak and then during peak electricity usage you run slower. Since a smelter consumes so much power this can significantly level the grid usage.

Would that be economical? Places with abundant geothermal power like Iceland are probably going to make much cheaper aluminum smelting than anywhere else.

Usually its done with standard hydropower not geothermal, lots of aluminum smelting in Quebec. China produces like 10x more than the next highest producing country.

Re: The humble water heater could be the savior of our energy infrastructure woes

#60

Post by anonymousisme »

s0rce wrote: post #19
otterley wrote: post #14

Earlier quoted context omitted.

"Cold" basements rarely fall below 50 degrees Fahrenheit/10C. There's plenty of thermal headroom below that for heat pumps to work. Heat pumps already work outdoors at below freezing. I don't think there's anything to worry about.

More of a problem is when your water heater is within your conditioned space envelope and in the cold months when you are heating your space the hot water heater takes that heat. Its not a huge issue but you do run the heater extra for the heat that's going into your hot water. If you've got an air source heat pump outside then its just an extra step.

I was thinking the same thing. You don't get something for nothing. Assuming the water heater is in the conditioned space, it will just make the central heater work harder (and consume more fuel) during the winter months. Maybe this is offset during summer months when it can help the AC cool the space.

None of this applies if the water heater is not in a conditioned space, but that's not feasible in (common) environments with cold winters.

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