On Friday, August 7, 2015 at 8:56:00 AM UTC-5, trader_4 wrote:
On Wednesday, August 5, 2015 at 10:12:47 PM UTC-4, micky wrote:
In alt.home.repair, on Wed, 5 Aug 2015 18:42:25 -0700, "taxed and spent"
wrote:

Are they supposed to be changed preemptively after so many years, but before
they fail?

No, they last 10 or 20 years or more and there's no reason to replace
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. .

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.

What Micky writes about the replacement procedure is true. The same properties that keep a lot of water from quickly coming out of a water filled jug when it's immediately turned upside down and goes "glug glug" apply to a water heater. If no air can enter the top of the water heater, not much water will escape when you quickly swap out the element.

I've replaced quite a few electric water heater elements. First turn off the power to the heater. Turn off the water going into the unit. Open a hot water faucet to relieve the pressure in the tank then turn the faucet off. You can also use the TP valve to relieve the pressure but make sure it's not flipped open before you start to replace the element. Of course disconnect the defective element which should have already been determined. Stuff a towel under the nipple where the element screws in or bolts in. Have the other element ready when you pull the old one out so you can immediately slip the new element right in. You should put some Teflon thread sealer on the screw in type when you get it ready, I've used the Teflon paste. Very little water should escape and wind up on the towel if you swap the elements quickly. Sometimes there is calcium buildup on the element making it hard to get out so you'll have to wiggle and yank it out(no sex jokes please). You should have a shop rag ready to wipe out the threads in the nipple of calcium from the element if it had deposits. Even with the extra time it takes to get an encrusted element out, there should still be little loss of water. If you're not sure you can do the quick swap even with some help, you can always drain the tank before you get started. ᕦ( ͡° ͜ʖ ͡°)ᕤ

[8~{} Uncle Tank Monster