Electric water heater: OK to turn it off?

[ishoot308]

Originally Posted by SailinAway

50-gallon water heaters are from the era when we believed that bigger is better and everything in our daily life must be super convenient and always at hand. I don't think we can afford that any more, financially or environmentally. I had a 53-gallon water heater installed only because (a) I didn't want to turn on the oil boiler in the summer to take a shower and (b) I knew that a 10-gallon heater would impact the resale value of the house. I could easily live happily with two gallons of hot water per day, mixed with cold. Surely there is a more efficient way to obtain that than a 24/7 53-gallon water heater! Hence my original post! For the life of me I still don't clearly see the solution in all that has been said in this thread.

Sounds to me like a perfect example of a tankless on demand system you want. If you don’t want to pay for the expense for this system, shut the breaker off on your current system…

[SailinAway]

Originally Posted by ishoot308

Sounds to me like a perfect example of a tankless on demand system you want. If you don’t want to pay for the expense for this system, shut the breaker off on your current system…

I'm warming up to the idea of a small tankless unit for the shower. Can someone post a link to a suitable appliance?

EDIT: Woops, I think I meant to say "under sink water heater."

[XCR-700]

Originally Posted by SailinAway

I'm warming up to the idea of a small tankless unit for the shower. Can someone post a link to a suitable appliance?

I have a Rinnai RL94 thats 9 years old and so far has been a near flawless performer. I say near flawless as the installer had originally installed it with one of the DIP switch settings in the wrong option, and it was timing out periodically. Once that was changed to the correct option it has now been 100% flawless. I believe they have several different flow rates and other options to consider, so you need to do your homework and only buy as much heater as you need. In my case the Model 94 flow rate allows you to have the clothes washer running and take a shower or 2 people showering in different bathrooms at the same time and never see any reduction in flow. Well assuming you are on city water and/or have a good flow from your well.

I see no down side and on the plus side, there is energy savings to be had, no tank to rust out, and no volume of standing water to grow bacteria. Some argue they cost more, but I dont think I paid more than if I bought a good brand/model of tank style heater.

Take a look!

Good luck.

https://www.rinnai.us/residential/ta...-water-heaters

[ishoot308]

Originally Posted by SailinAway

I'm warming up to the idea of a small tankless unit for the shower. Can someone post a link to a suitable appliance?

I have had this one for 13 years now trouble free! It is used from ice out till mid November. In the spring when water temp is 34 degrees it still heats water flawlessly! No issues with two showers going at once or laundry while showering. We use approximately three 100 lb propane tanks per season strictly for hot water and yes we have a lot of visitors so many extra showers taken during the week. The wife is also a “laundry nazi”!

I am not a plumber and don’t know much about these and all I can say is I love mine and wouldn’t be without it.

Here is a couple pics of it and the spec sheet on the side…

Dan

[Garcia]

Originally Posted by ishoot308

I have had this one for 13 years now trouble free! It is used from ice out till mid November. In the spring when water temp is 34 degrees it still heats water flawlessly! No issues with two showers going at once or laundry while showering. We use approximately three 100 lb propane tanks per season strictly for hot water and yes we have a lot of visitors so many extra showers taken during the week. The wife is also a “laundry nazi”!

I am not a plumber and don’t know much about these and all I can say is I love mine and wouldn’t be without it.

Here is a couple pics of it and the spec sheet on the side…

Dan

Thanks for this. I have a 20 year old propane hot water heater (tank) on the island that I know is at the end of it's life. I go back and forth about replacing it with something like this - leaning toward doing it. I like the idea of "trouble free" as while I am willing to try and fix things, sometimes my enthusiasm is greater than my abilities - and getting tradespeople out to the islands can be a challenge, esp. when I tend to be there on weekends rather than during the week.

[SailinAway]

At this point I've had the water heater turned off at the breaker for the past month. My August kWh usage was 34% lower than August last year with a combination of strategies.

Yesterday I closed the hot and cold valves on the water heater to make sure I'm not bathing with water from the heater due to the risk of bacteria. I'm drawing cold water from the town supply for bathing.

Q1: My handyman says I should drain the water heater at this point to avoid mold etc. growing in it and also rust. Is he correct?

Q2: Would the simplest solution be a well-insulated 10-gallon tank placed next to the 53-gallon tank? That way the next owner of the house could use the larger tank if they prefer, while I would not use the large tank from this point forward.

[John Mercier]

Q1. What would the mold be eating? It shouldn't increase rust.
But if you aren't going to use it for a long period of time, draining it would be best... and shouldn't be that hard.

Q2. You could. I remember when my grandmother would fill the tub about quarter/half way and then poor water from the kettle heated on the wood stove to warm it up.
Since I prefer showers now... that is a bit harder to do.

[ApS]

Originally Posted by SailinAway

At this point I've had the water heater turned off at the breaker for the past month. My August kWh usage was 34% lower than August last year with a combination of strategies.

Yesterday I closed the hot and cold valves on the water heater to make sure I'm not bathing with water from the heater due to the risk of bacteria. I'm drawing cold water from the town supply for bathing.

Q1: My handyman says I should drain the water heater at this point to avoid mold etc. growing in it and also rust. Is he correct?

Q2: Would the simplest solution be a well-insulated 10-gallon tank placed next to the 53-gallon tank? That way the next owner of the house could use the larger tank if they prefer, while I would not use the large tank from this point forward.

Why not use your breaker-controlled tank for other chores? (Watering, rinsing, cold water washing machine chores). Maintaining a regular (cold) flow through the water heater shouldn't be difficult. I do it, and turn the breaker back "on" 15 minutes before a shower. The freshly-heated water rises to the top of the heater, and is drawn-off first. You'll know when your shower is nearly over--automatically.

Back when I had 120-v water heaters, I put a household timer on them to save on excessive heating. It doesn't need to be really hot to be useful. One was 40-gallon, the other was 90. (!)

Speaking of timers, take two $8 household timers--plugged together--to operate an irrigation/utility pump one hour a week from a lake (or cistern). Set one timer to go on for three hours, the second to operate one hour. Using this technique, you don't have to be present at the lake to water your plants. As to the number of days and hours, YMMV.

Insurance-based water heater "take-outs" will help to economize. This being hurricane season, advertise "WTB" on Craigslist. I sold two to a desperate contractor who had a "tent city" of volunteer electricians with no hot water.

I should add that mold is suspect in peripheral neuropathy, a nerve condition experienced by ~15% of Americans.

[SailinAway]

Originally Posted by ApS

Why not use your breaker-controlled tank for other chores? (Watering, rinsing, cold water washing machine chores). Maintaining a regular (cold) flow through the water heater shouldn't be difficult.

I don't get this. Why would I draw cold water from the tank rather than directly from the town inlet? Just to make sure I understand: Cold water enters the tank from the town inlet, gets heated, and exits from the tank. Cold water to the house (e.g., sinks, washing machine) comes directly from the town inlet. Correct? That why I don't understand your reference to getting cold water from the tank for the washing machine.

Originally Posted by ApS

I do it, and turn the breaker back "on" 15 minutes before a shower. The freshly-heated water rises to the top of the heater, and is drawn-off first. You'll know when your shower is nearly over--automatically.

What I found online: “A 50-gallon hot water heater with 5,500-watt elements set to 120 degrees takes about 1 hour and 47 minutes to heat water coming in to the unit at 40 degrees.”

Originally Posted by ApS

Insurance-based water heater "take-outs" will help to economize. This being hurricane season, advertise "WTB" on Craigslist. I sold two to a desperate contractor who had a "tent city" of volunteer electricians with no hot water.

What's a water heater take-out? You mean you sold your water heater to a contractor and he did the removal? I need to save my 53-gallon tank for the next family that lives in my house, because it has been suggested here that I sell my house and move! (An idea that I've contemplated every day for the last 10 years.)

[ApS]

Originally Posted by SailinAway

What's a water heater take-out? You mean you sold your water heater to a contractor and he did the removal? I need to save my 53-gallon tank for the next family that lives in my house, because it has been suggested here that I sell my house and move! (An idea that I've contemplated every day for the last 10 years.)

I replaced a 7 y-o water heater because, after being partly submerged during a hurricane's surge, turning on the breaker resulted in a plume of smoke.

Days later, when the plumber replaced it, it was put out by the curb. Looking at the now-exposed wire connections, I realized that the heater was still good.

As a backup, I'd previously purchased a 20-gallon, 120-V, water heater for $50. Small, it may have been smaller than 20-gallon.

Those two "take-outs" I sold to the above contractor for $150. (Explaining all that I knew). So, I was "ahead"...sorta...

[Patofnaud]

Originally Posted by SailinAway

What I found online: “A 50-gallon hot water heater with 5,500-watt elements set to 120 degrees takes about 1 hour and 47 minutes to heat water coming in to the unit at 40 degrees.”

Remember, you do not have to heat the WHOLE tank to be able to take a shower.

20->30 mins is more reasonable.

[SailinAway]

Originally Posted by Patofnaud

Remember, you do not have to heat the WHOLE tank to be able to take a shower. 20->30 mins is more reasonable.

You make it sound like I can just heat the top 5 gallons in 20 rminutes and get a 10-minute shower. Is that really how a water heater works? Or is all the water mixing inside it such that ALL the water has to reach 140 degrees?

[DickR]

Originally Posted by SailinAway

You make it sound like I can just heat the top 5 gallons in 20 rminutes and get a 10-minute shower. Is that really how a water heater works? Of is all the water mixing inside it such that ALL the water has to reach 140 degrees?

A typical electric water heater of any size has two heating elements, upper and lower, with two thermostats. My 40 gallon tank has two, 4.5 KW each. The upper element and thermostat are located somewhat below the top of the tank, and not right at the top. Starting cold, the upper thermostat turns on that element, and the lower element is off. When the upper thermostat is satisfied, with enough hot water above it to take a shower (for most people), that thermostat turns off the upper element and sends power to the lower thermostat. The lower element heats water from there up to the upper element. When the lower thermostat is satisfied, that element is turned off. Power remains available at the lower thermostat, to turn that element back on after some use of hot water. If enough hot water is drawn, the upper thermostat switches off power to the lower thermostat and turns on its element again.

[SailinAway]

Two things I want to add to this discussion.

(1) Legionella: I did an experiment today. I turned the thermostat to about 140 degrees (it only has markings for 125 and 150). The water heater is in the basement, which is about 45 degrees. I had not used the heater for about two weeks. I ran the heater 1h 15 min. The temperature at the kitchen faucet was 130 degrees. I ran the heater another 15 minutes and the temperature at the faucet was 140. So total 1 hour 30 minutes to reach 140. Research shows that to kill Legionella it takes 140 degrees for 32 minutes. Granted, the temperature at the faucet is lower than in the tank. Still, this experiment shows that with a cold tank, it takes a fairly long time to heat the water to 140 for 32 minutes---perhaps 2 hours.

(2) My new plan: I opened up the panels on the heater and found that it only has one thermostat, at the top. I'm thinking of disconnecting the lower element. I think the top element would provide enough hot water for a good shower. Two questions: (1) Do you see any problem with this plan? (2) Can I disconnect the lower element myself? How would I do that? What would I need to be careful about? (Response: Turn off the breaker. )

I have some R30 insulation that I plan to wrap around the tank and put on the top. I will also insulate the pipes. The I'll turn the water heater on for one month and see what my electric bill is.

This will be in lieu of the best solution, which is to get either a smaller tank or an on-demand heater.

[tis]

Sailin, is this a hobby for you?

[SailinAway]

Originally Posted by tis

Sailin, is this a hobby for you?

My hobby is saving money while staying safe and healthy. I consider all precautions and suggestions I receive, especially those that are based on evidence, experience, and logic.

Example: Health safety of using only the top element. You can only answer that by thinking about questions like: Does water in the lower, middle, and upper zones mix together? Or does hot water at the top remain at the top, while lukewarm water remains in the middle? If water in the top zone is heated to 140 degrees for 32 minutes, is a short shower drawn only from the top zone, where Legionella has been killed? Or is there a risk that lukewarm water from the middle zone will end up in the shower water? Is using only the top element any different from using the top and bottom elements with regard to bacteria? After all, even with two elements, there are still heat zones in the tank from cold to lukewarm to hot, so wouldn't that be equally dangerous? When you're taking a shower you can sense when the water is getting colder---is that dangerous?

Somewhere in a two-element tank there has to be water in the 68°–122° (some sources say 130°) zone where Legionella grows. I surmise that if the thermostat is set to 140, the water in the middle zone never makes it to the faucets because hot water rises to the top of the tank. There is no way to ensure that the entire tank is 140 degrees all the time, and it's not necessary that that occur. So the question becomes, is there enough HOT water at the top of the tank for low usage, such that one element would be sufficient to provide Legionella-free water? And if a person uses more water, will one element replenish the hot water fast enough for safety? My intuition says that one element would be enough for my low use, but I will try to confirm that before turning off the bottom element.

Some people have no patience with such questions and say, "Just turn the heater on 24/7 and get it over with." But inquisitive people have spent a lot of time investigating just such questions because health safety, fire safety, and conservation of water and power are important to them.

Not being curious is what led to Legionnaire's disease outbreaks in apartment buildings and homes. People just blindly accepted statements that water heaters should be set at 110 degrees to conserve power, or that 125 degrees kills Legionella bacteria. Even the government issued such statements. Science proved them to be false. Now it's hard to go back and change people's minds about what they heard for years. Is your water heater set to less than 140 degrees? Why? Is that based on facts, beliefs, or habits?

[LikeLakes]

Sailin, well said and I understand what you are trying to accomplish from your various threads. I also appreciate the discussions, they are interesting and I learn from the input from everyone.

When I say my 2 cents is I'd leave the hot water heater on, please understand it's not coming from a "spend the money, spend the energy, stop trying to save" point of view. To the contrary, I'm very interested in saving energy, renewable energy, and saving water, not to mention am just generally environmentally conscious.

Instead, my reasoning comes from a lot of experience not only as a homeowner, but also in various industrial settings where I've got a lot of experience with heating, cooling, various fuel sources, etc. My experience tells me that generally it's best to operate a piece of equipment the way it was meant to operate. Meaning, run your hot water heater set up the way it was made to operate, shut it off completely when you choose to. That's all. And I may very well be wrong about that, I'm just giving my opinion.

[DickR]

Originally Posted by SailinAway

...
(2) My new plan: I opened up the panels on the heater and found that it only has one thermostat, at the top. I'm thinking of disconnecting the lower element. I think the top element would provide enough hot water for a good shower. Two questions: (1) Do you see any problem with this plan? (2) Can I disconnect the lower element myself? How would I do that? What would I need to be careful about? (Response: Turn off the breaker. )...

Something doesn't make sense in the thermostat configuration you describe. As an element heats water around it, that water, considerably hotter than the bulk water away from the element, rises and displaces cooler (well, less hot) water until the heated water meets water at the same density/temperature. While there certainly is some mixing and heat transfer in this convective flow, in general the level of sufficiently hot water moves downward toward the element doing the heating until the thermostat controlling power to the element is satisfied.

As I explained back on Sept 30 (post #92), I would expect there to be a thermostat associated with the lower element. When the upper one is satisfied, it would turn off power to the upper element and switch to powering the bottom thermostat/element. When the level of sufficiently hot water got all the way down to the lower thermostat, then the thermostat would shut off power to its element, and it would be that element that would come back on first if hot water use brought the hot/cold interface back up over that point. If continued hot water draw brought the interface level up to the upper thermostat, then that one would cut power to the lower thermostat and turn its own element back on.

This leads to questions. If there is only one thermostat, at the top, and it controls power for both elements, then it would turn off when the hot water level comes down to that thermostat, at which point heating would stop altogether, and the water in the tank between the two elements never would reach the set point. How would the lower element remain on long enough to finish heating all the water in the tank? If the upper thermostat controls only the upper element, when would there be any power to the lower element, and what would control power to it? Safety requires control of power to that element.

Actually, never getting enough hot water for more than one short shower, followed by recovery of hot water availability after a short time, usually means failure of the lower thermostat or element. Not getting any hot water at all usually means failure of the upper assembly.

Given that you have two heating elements, each would have its own thermostat, for control purposes. The look and function of the upper element/thermostat assembly will be different from that of the lower one; they are not interchangeable. If one fails, the correct type must be used for replacement.

As to disconnecting the lower element, to save power by not having the entire tank contents kept hot, yes, that could be done. Be sure to turn off the breaker before fiddling in there, and put twist caps on the wire ends, for safety. It might also be a good idea to attach a clear note to the tank, explaining what's been done and why.

I have to wonder about how much power use would be saved by disconnecting the lower element. Some savings would come from reduced heat loss from the lower half of the tank to its surroundings, since the water there would be cooler than at the top and the rate of heat loss is proportional to temperature difference between hot water and cold surroundings. Still, the hot water at the top of the tank will be cooled at some considerable rate by direct conduction of heat from hot water to the cold water below and in direct contact with it. The thermostat will come on regularly to keep the top water up to setpoint. With both elements wired, it would be the lower element that would cycle on and off to replace heat loss, but the loss rate would be somewhat higher.

I do think that the same overall power savings can be achieved without disconnecting the lower element simply by adding a lot of insulation around the tank and piping. Heat transfer in this situation is governed by Fourier's law: Q = U*A*dT, where Q is rate (BTU/hr), U is a heat transfer coefficient (BTU/sq.ft/hr/degree F), A is area of heat transfer, and dT is temperature difference (F). Insulation value R is defined as 1/U, so that the heat loss equation could be written as Q=A*dT/R. The important thing to note is that cutting U in half, by doubling insulation R, cuts the rate of heat loss in half. At some point there is little additional saving to be had by increasing total insulation R (more thickness). But we are talking about just a water heater, so the total area involved is small, and adding even more insulation is cheap.

[SailinAway]

Dick, I will remove the upper and lower panels and take photos of what's in there when I get a chance.

[Seaplane Pilot]

I think it would be easier to move to Florida.....

[TheProfessor]

Originally Posted by SailinAway

or an on-demand heater.

Great. Save money. Spend the $1,500+ on one of these.

Except the payback or break even will be about 22 years.

Sounds like a real good idea.

Pay the electric coop piper. Or pay the plumber installer piper. Or pay the propane company piper.

One of those pipers is going to win out.

[LikeLakes]

I'd recommend you have an electrician, or someone with very solid electrical skills, do the disconnect of the 2nd element. You've stressed safety all along the way with your research and changes and re-wiring water heaters is definitely not safe for someone to just get some advice and try themselves.

And, just once again tossing in my 2 cents, I wouldn't do it. You have a water heater, let it heat water, shut it off when you don't want hot water. You are concerned about legionella, yet you are proposing heating SOME of the water in the tank to a temp you think the water is all at and for a period of time you think is safe. Yet half that tank or more won't be at that temp, won't be at the same duration, due to disconnecting one element. Makes no sense to me.

[NH.Solar]

I installed a solar array for a client about five years ago that had a fairly large all electric house, including the biggest electric tankless I have ever seen. I belive it was made by Bosch. The thing that caught my immediate attention was that it required two 30 amp and one 40 amp 240 volt breakers. The client explained however that he was very happy with the setup becuase most of the time it drew zero power, but if the kids and grandkids were all in residence for the holidays he never ran out of hot water. A unique situation to be sure but a good solution.
I've installed gas tankless heaters in two of my previous homes and for the most part were pleased with them. One however would act up occasionally because the well water occasionally had a small amount of very fine silt the would get by the inlet filter. After I figured it out it would onlky take a few minutes to remove the water metering valve from the front of the unit and rinse it off.
In my current home I installed a Rheem Marathon tank water heater and I'm so pleased with it that I will probably install another in my next house. The tank is one "tupperware" plastic hull (like used in kayaks) moulded inside another and then they blow 3" of foam between the two hulls. Its efficient, has a lifetime warranty, and is very light and was easy to install. Perhaps the smallest version of the Marathon series or an electric tankless would meet your needs?

The garage space were I placed my 70 gallon Marathon has 12' walls and I was able to weld up a rack that elevated the water heater by four feet and placed this next to my basement woodstove. Then I formed 60' of 3/4 soft copper pipe around the woodstove's flue pipe and tee'd the top hot outlet from the loop into the Marathon's outlet to the domestic water and radiaint floors, and tee'd the return from the water heater drain back to the feed to the coil on the flue. It works simply and perfectly using the convective rise all winter, and the natural striation of hot to cold water keeps the lower portion of the loop from pulling heat out of the water heater in the summer. My water heating costs in the summer are minimal, and in the winter are virtually nil. Two caveats to this system; one would want to install a mixing valve in the domestic feed because the water in the tank can get very hot, and second there should be absolutely no shutoff valves anywhere in the convection coil loop. As long the loop is open the water will flow constantly, but it there were a shutoff and the flow stopped it could result in a steam explosion. I did install a 180 degree boiler pop off valve in my loop and plumbed the drain down to a pail on the concrete floor just in case, but it only activated once during an extremely cold windy night and even then only relieved itself of a gallon of water.

[LikeLakes]

Originally Posted by NH.Solar

In my current home I installed a Rheem Marathon tank water heater and I'm so pleased with it that I will probably install another in my next house. The tank is one "tupperware" plastic hull (like used in kayaks) moulded inside another and then they blow 3" of foam between the two hulls. Its efficient, has a lifetime warranty, and is very light and was easy to install. Perhaps the smallest version of the Marathon series or an electric tankless would meet your needs?

We installed the same Marathon heater, or maybe it's an 80 gallon, in our lake house. Amazing unit, barely feels warm from the outside which tells the story on the excellent insulation. Really a great option. Pricey to purchase, but worth it IMO.

[ApS]

Use the left (hot, red) faucet frequently to avoid "stale" water residing in the "shut-off-breaker" tank. (Although I don't think this is a real problem--even with lake water). Of course, there is no tank involved in the right (cold, blue) faucet.

Note, however, the left (hot, red) side is likely to have a taste of magnesium--or whatever anode is installed in the tank--so drinking from the left (hot, red) side might be objectionable.

And, yes, town water ultimately feeds both faucets. (Or both of the red and blue sides of single faucets)

Originally Posted by SailinAway

I don't get this. Why would I draw cold water from the tank rather than directly from the town inlet? Just to make sure I understand: Cold water enters the tank from the town inlet, gets heated, and exits from the tank. Cold water to the house (e.g., sinks, washing machine) comes directly from the town inlet. Correct? That why I don't understand your reference to getting cold water from the tank for the washing machine.

That's only regarding one's preference for a complete/fully cold-cycle washing.

[TheProfessor]

My Myson 325 Thermor is over 20 years old. Propane.
Made in England.
On demand instantaneous hot water heater.
Direct vent out the wall.
No electricity required.
Does have a pilot.
Starts heater by water pressure.
Works perfectly.

Unfortunately Reagan, Bush, Clinton did away with pilot light appliances.
Recently took cover off and all still looks new inside.

Works perfectly.

[John Mercier]

Originally Posted by SailinAway

I'm warming up to the idea of a small tankless unit for the shower. Can someone post a link to a suitable appliance?

It depends on your fuel options.
Electric or propane?

[SailinAway]

Originally Posted by John Mercier

It depends on your fuel options.
Electric or propane?

Electric....

[John Mercier]

Rheem has good ones.
I think you may be able to find them at one of the two Big Boxes.

Just determine the size that you need, because too large will need a panel and service upgrade.
We have quite a few of those going on in the Bristol area... and the pvc conduit is getting tricky to supply.