how long do electric water heater elements last?

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Are they supposed to be changed preemptively after so many years, but before they fail?
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In alt.home.repair, on Wed, 5 Aug 2015 18:42:25 -0700, "taxed and spent"

them early.
It's also not true that the water heater will always have a lot of crud in it. I mistakenly replaced mine after about 10 years, and I cut it open and there was just about 2 tablespoonsful of crud. It would have taken more than 300 years to reach the element.
What you should know is that when the time comes, you don't have to drain the tank to replace even the lower element. Turn OFF the electricity to the WH. Turn OFF the water going to the WH, turn ON the hot water somewhere until no more water comes out. Then unbolt or unscrew the element, pull it out and lickety-split put the new one back in and start screwing it (or the screws) in. When I did that I spilled only about a tablespoon of water into insulation just inside the outer cover. It evaporated eventually.
Saved all the hot water, and a bunch of time that it takes to drain the tank and refill it. .
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wrote:

It depends on he water PH. I once lived in a house with well water that was very acidic. It actually ate copper pipes, and water heater elements had to be replaced every 3 or 4 years.
I worked for a guy who lived in a town that had very high calcium in the water. In 3 years, his water heater was half filled with lime particles. The lower element was buried in it. I tried to flush out all the lime, but it was not possible. That 3 year old water heater had to be replaced. Everyone in that town has that problem.
So, this question has no answer.....
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In alt.home.repair, on Wed, 05 Aug 2015 23:51:55 -0500, snipped-for-privacy@spamblocked.com wrote:

You're right. I guess I meant in absence of history or neighbors sayin that WH wear out soon, he shouldn't assume it will happen soon.
And since they sell elements many places and it doesn't take more than an hour to put one in, there's no rush.
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Except this is a vacation rental, and when it goes out when a tenant is there and not the owner, a plumber is called. :(
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On 8/6/2015 1:14 AM, micky wrote:

I read some where that if you crank out the drain valve from the WH, and put in a full flow ball valve, you can drain a lot more crud than what the angle valve (provided) does.
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In alt.home.repair, on Thu, 6 Aug 2015 09:44:06 -0400, Stormin Mormon

That's at most only if there is crud to drain out. Mine had hardly any.
There have been a lot of posts over the years about that valve.
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In alt.home.repair, on Thu, 6 Aug 2015 23:19:26 -0700 (PDT), Uncle

It's the type I had and the type I cut open. I forget what the swirling is supposed to do. ???
Because there has been no detectable crud in the water that comes out of the sink that I touch with my hands, and if there were crud in the bath water, I think I'd notice it. That just leaves the washing machine where i probably would not notce it. The garden hose where I would not notice it, but I don't use very often). And the aerators, which have never clogged or slowed. If there crud in the water it would be in all the outputs, not just the garden hose.
**It's probably the type I have now, since I bought the new one from the same place, in orde to get the inlet and outlet pipes in the same place I'm somewhat compulsive and didn't want any Z or flexible connections.

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wrote:

The stuff that accumulates in the water heater is dissolved calcium in the water. YMMV depending on what is in the water to start with. When I was in the north east our water was very good and water heaters lasted forever. Here in Florida, they don't last that long. Ten years is typical.
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In alt.home.repair, on Sat, 08 Aug 2015 11:08:47 -0400, snipped-for-privacy@aol.com wrote:

Bear that in mind, Taxed.
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On Wednesday, August 5, 2015 at 10:12:47 PM UTC-4, micky wrote:

Interesting procedure. I'm surprised that it works. The hole in the tank for the element is large and I would think even without a way for air to enter at the top, water would still come pouring out. And if for some reason you can't get the new one in, I guess you better be prepared for the consequences. And the "saved all the hot water" part sounds positively dangerous.
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In alt.home.repair, on Fri, 7 Aug 2015 17:49:11 -0700 (PDT), Uncle

When my first element failed, I thought I had to buy a replacement of the same brand AOSmith. Only one vender around here but right on the way to work Plumbing supply store. He told me how to do it. I probably paid more than at a hardware store, but well worth it for the added info.

The water stays pretty hot for a 2 -4 days if you don't use any. Of course the more you use, the cooler it gets.

Oh, yeah. I think I left out turnng the faucet off again. If left on, air would go in and water woudl come out of the WH. Turn it off.

This is especially valuable for plumbers, who don't want to spend an hour draining the tank and an hour filling it before they can turn it back on, either for free or trying to bill the customer for 2 more hours or more.
But it went very smoothly for me. Maybe 3 seconds with nothing in the hole, and another 5 seconds before I started screwing in the new element. Less than 3 tablespoons I think.

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taxed and spent wrote:

thermostat few years ago. Still working good. Having two element(top and bottom) I'd think replacing element is not rush job.
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On Wed, 5 Aug 2015 18:42:25 -0700, "taxed and spent"

In my experience their life is highly variable. I've had them burn out in a couple years and I've had them last 20 years. One thing that seems to make them burn out faster is that the bottom ones wind up down in the muck at the bottom of the tank and that shortens their life.
speaking of muck, I've had far far less muck form by turning the temperature down below "normal" on the dial. I keep it around 120 degrees or less and it seems to reduce the formation of muck and crud. When I used to run them hot they would build up muck all the way up to teh bottom element (and make it burn out) in only a few years. I almost couldn't get one of the elements out it was so encased in calcium buildup.
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On 8/7/2015 6:29 PM, Ashton Crusher wrote:

Less than 120 is a good range for legionella though. I opt for 130 for safety.
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NIH has some differing views but you can find lots of others:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC118082/
<<L. pneumophila multiplies at temperatures between 25 and 42?C, with an optimal growth temperature of 35?C>>
That's 77F to 107.6F with an optimal growth temperature of 95F.
Legionella pneumophila (203). Legionellae are intracellular parasites of freshwater protozoa and use a similar mechanism to multiply within mammalian cells (91). These bacteria cause respiratory disease in humans when a susceptible host inhales aerosolized water containing the bacteria or aspirates water containing the bacteria.>> Again:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC118082/
The key to infection is "inhaling aersolized" water or actually aspirating water into the lungs. My understanding is that it grows best in the condensate of rooftoop cooling towers and not in water heaters:
<< During the past 3 years, the epidemiology of Legionnaires' disease has been dominated by the occurrence of several large outbreaks, two linked to cooling towers and one linked to a whirlpool spa. In April 2000, a large outbreak of Legionnaires' disease occurred among persons visiting the newly constructed aquarium in Melbourne, Australia (9). By June, 119 persons were confirmed to have Legionnaires' disease, and four (3.6%) persons died. This outbreak was due to a new cooling tower which had recently come on line. It demonstrated that even new cooling tower systems pose a risk when coming on line and that decontamination procedures should be followed.>>
And yes, I realize hotter water is better in the case of killing Legionnaire's bacteria but the tradeoffs are a greater chance of scalding. That said, OSHA says this:
https://www.osha.gov/dts/osta/otm/legionnaires/faq.html
<< Q. Can my home water heater also be a source of LDB contamination?
A. Yes, but evidence indicates that smaller water systems such as those used in homes are not as likely to be infected with LDB as larger systems in workplaces and public buildings.>>
One of the reasons it thrives in cooling towers is that it prefers warm, stagnant water with a source of food. A cooling tower is pretty much the ideal growth medium because bugs, bird droppings and all sorts of nasty food for bacteria live there. The first diagnosed outbreak that gave the bug its name was found in the Legionnaire's hotel cooling tower.
<<Q. Do you recommend that I operate my home water heater at 60?C (140?F)?
A. Probably not if you have small children or infirm elderly persons who could be at serious risk of being scalded by the hot water. However, if you have people living with you who are at high risk of contracting the disease, then operating the water heater at a minimum temperature of 60?C (140?F) is probably a good idea. Consider installing a scald-prevention device.>>
Those most likely at risk probably should amp up the temperature of their water heater: a.. Organ transplants (kidney, heart, etc.) b.. Age (older persons are more likely to get disease) c.. Heavy smoking d.. Weakened immune system (cancer patients, HIV-infected individuals) e.. Underlying medical problem (respiratory disease, diabetes, cancer, renal dialysis, etc.) f.. Certain drug therapies (corticosteroids) g.. Heavy consumption of alcoholic beverages Since I am not in the high risk category and the water in my 120F water heater doesn't have much of a chance to get stagnant, I don't worry about it. Too much. Many other nastier demons out there.
Here's something really nasty that can be found in warm freshwater.
http://www.webmd.com/brain/brain-eating-amoeba
<< The so-called brain-eating amoeba is a species discovered in 1965. It's formal name is Naegleria fowleri. Although first identified in Australia, this amoeba is believed to have evolved in the U.S. There are several species of Naegleria but only the fowleri species causes human disease. There are several fowleri subtypes. All are believed equally dangerous.
N. fowleri is microscopic: 8 micrometers to 15 micrometers in size, depending on its life stage and environment. By comparison, a hair is 40 to 50 micrometers wide.
Like other amoebas, Naegleria reproduces by cell division. When conditions aren't right, the amoebas become inactive cysts. When conditions are favorable, the cysts turn into trophozoites -- the feeding form of the amoeba.
Naegleria loves very warm water. It can survive in water as hot as 113 degrees Fahrenheit.
These amoebas can be found in warm places around the globe. N. fowleri is found in:
a.. Warm lakes, ponds, and rock pits b.. Mud puddles c.. Warm, slow-flowing rivers, especially those with low water levels d.. Untreated swimming pools and spas e.. Untreated well water or untreated municipal water f.. Hot springs and other geothermal water sources g.. Thermally polluted water, such as runoff from power plants h.. Aquariums i.. Soil, including indoor dust Naegleria can't live in salt water. It can't survive in properly treated swimming pools or in properly treated municipal water.
Most cases of N. fowleri disease occur in Southern or Southwestern states. Over half of all infections have been in Florida and Texas.>>
As for scalding v. Legionnaire's, there are apparently 10K to 50K cases a year of LD compared to 500K for scaldings. That makes the risk from hot water burns far more likely than catching Legionnaire's. I think the increased longevity of the heater and the lessening of the scald risk are well worth turning the dial back. Saves money, too. YMMV
Over 500,000 scald burns occur annually in the United States. The two highest risk populations are children under the age of 5 and adults over 65.
Did you know?
a.. Hot liquids can cause life-threatening burn injuries. b.. Scalds are the number-one cause of burn injury to children under age 4. c.. Burn accidents frequently occur when parents or caregivers are in a hurry, angry, or under a lot of pressure. d.. Coffee, tea, soup and hot tap water can be hot enough to cause serious burn injury. e.. Scald and steam burns are often associated with microwave oven use. * f.. When tap water reaches 140? F, it can cause a third degree (full thickness) burn in just five seconds. g.. Hot tap water accounts for 17% of all childhood scald hospitalizations. www.burnfoundation.org/programs/resource.cfm?c=1&a=3
*Ever heat water in a coffee mug and have it boil over just as you open the door? It's very nasty and I assume that it's the same sort of phenomenon where water can freeze over in seconds if it's supercooled and it's disturbed by a loud noise.
https://en.wikipedia.org/wiki/Supercooling
<<Droplets of supercooled water often exist in stratiform and cumulus clouds. Aircraft flying through these clouds see an abrupt crystallization of these droplets, which can result in the formation of ice on the aircraft's wings or blockage of its instruments and probes, unless the aircraft are equipped with an appropriate de-icing system. Freezing rain is also caused by supercooled droplets.>>
IIRC (and these days mostly I don't) the Air France flight that crashed in the Atlantic Ocean a few years ago had a pitot tube speed sensor (actually 3) whose internal heaters were all overwhelmed by supercooled water.
https://en.wikipedia.org/wiki/Superheating
Aha! The site above finally explains why the coffee mug sometimes "spits up" all over the inside of the microwave (but fortunately not my face)
<<Superheating is an exception to this simple rule; a liquid is sometimes observed not to boil even though its vapor pressure does exceed the ambient pressure. The cause is an additional force, the surface tension, which suppresses the growth of bubbles.
Surface tension makes the bubble act like a rubber balloon (more precisely, one that is under-inflated so that the rubber is still elastic). The pressure inside is raised slightly by the "skin" attempting to contract. For the bubble to expand, the temperature must be raised slightly above the boiling point to generate enough vapor pressure.
What makes superheating so explosive is that a larger bubble is easier to inflate than a small one; just as when blowing up a balloon, the hardest part is getting started. It turns out the excess pressure due to surface tension is inversely proportional to the diameter of the bubble.>>
Another mystery revealed by Google and Wiki. (-:
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Bobby G.




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<stuff snipped>

I haven't taken mine apart but it's outlived its predecessor which used to run at 140F (I keep mine at 120F coming out of the tap - eventually - but it takes a while to get there.) We'll see when this one dies. I also trimmed the cold water input to the tank to try to limit the thermal shock of 36F water (the lowest I've ever measured) hitting 120F internals.
What I haven't come across yet (still looking) is something on the web that explains how water heaters build up so much sediment. The "duh" answer is of course, sedimentation but it seems to be more complex than that otherwise there would be sediment filtration on the incoming cold water line.
You would also think that heating the water causes more sediment to dissolve so I am not sure exactly what most causes gunk buildup. I suspect it's the quality of the water, but I haven't seen any study that apportions the causes of sedimentation.
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On Sat, 8 Aug 2015 10:28:16 -0400, "Robert Green"

Yes, you would think heating it would make it dissolve stuff, not precipitate it but perhaps the fact that it just sits there perking away (figuratively) much of the day with no water movement somehow results in precipitates dropping out. Or perhaps the mixing of cold and hot water causes precipitation regardless of it being on average quite hot and lessening the high temp results in less of that presumed effect.
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wrote:

Well, I'll keep looking. What's clear is that gunk DOES build up and with some heaters/areas it builds up pretty quickly. It would be nice if lowering the temperature not only saved money, but lengthened the service life of the heater. We'll get at least one more data point when mine finally goes. I started seeing some water dripping lately. Maybe I'll find out soon. )-:
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On Wednesday, August 5, 2015 at 9:42:30 PM UTC-4, taxed and spent wrote:

The lower elements tend to have shorter lives than the upper element. When one goes, there is a difference, but some hot water is still available. It will take longer to heat.
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