Bad water heater element, guests coming soon!

I am a computer guy, not a handy-man, so forgive the stupidity of my question...
I have a Rheem 40 gallon water heater. 240 volts, 4500 wattage, model number 81V40D C ...
My dad, a water heater inspector for TVA, tells me the top element is probably bad (We have some hot water, but runs out pretty fast now... i trust his judgement since he has done it for over 25 years).
So I go to home depot to grab a new element, and I am seeing screw in, twist in, walk in, fly in, run in, etc... :^)
can someone just tell me what to get and where to get it? Pretend I am your stupid son and feel sorry for me and hook me up. My dad just says "Buy a new hot water heater, they dont cost much" but I dont have time for all that, guests arrive in about 10 days.... I know all i will have to do is turn the breaker off, let the water cool, drain the tank, and pull (or twist, or unscrew) the element out and slap a new one in there...
However, I dont have an ohm meter.... i mean, does the average guy have one of these lying around? Ive replaced light fixtures and ceiling fans, but the more i read the more people seem to freak out about the water heater still haveing power in it even after turning it off at the breaker... what gives?
anyway, thanks in advance! Jazz Mann
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Ask over at HVAC-Talk . com
They love to answer DIY questions over there!

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Your dad may be right about just replacing the whole thing. You need to open the upper access panel, remove the insulation and check the two terminals on the upper element with a volt meter to see that you indeed have 240 volts across them, if not, you may need an upper thermostat, if you do, check to see what holds the element into the tank, and remove it. Mind you, if its a screw in, you need a pretty big socket wrench to get it out. With it removed, bring it to a plumbing supply and get a replacement and gasket, and reinstall it

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Don't have time for all that? You might be a little mistaken about how hard it is the install one. I myself had to install a new gas water heater and that is by far more complicated - it took about 30 minutes once it was on-site for me to do. Of course my buddy helped out, just because they are empty doesn't mean they are light!
How old is your water heater - that would greatly help us provide more information.
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get any hot water. That is the one that comes on first. That is the "quick recovery element" to put some hot water in the top of the tank right now. When the top thermostat is made it switches to the bottom and heats up the rest of the tank. If top one is bad it won't make any hot water to make the stat and flip to the bottom so you are stuck.
A quick look under the bottom cover will tell you what kind of element it is. If it has 4 bolts around the wiring terminals (3" or so pattern) it is bolt in. A screw in only has a big hex nut type end.
BE SURE TO TRIP THE BREAKER BEFORE YOU POKE AROUND IN THERE!
Also be sure water is running free out of a hot water faucet before you turn it back on after replacing the element Let it run a minute or more to be sure there isn't an air pocket in the top or you WILL have a bad top element.
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snipped-for-privacy@aol.com wrote in wrote:

I agree.

I disagree...if the bottom one still works.

Disagree again. Bottom one comes on first because that's where the coldest stored water is. Also, the cold water in dip tube goes to the bottom of the tank.

Disagree. When the top thermostat says turn on, it shuts the bottom one, which should already be on, off. When the top is up to temp, the bottom will go back on to bring the lower half of the tank up to temp.

Ughhhh! Incorrect.

Absolutely key advice!

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Mr Al is correct, I didn't want to take the time to type it all out. :-)
wrote:

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wrote:

Hmmm. Now I am rethinking this (after posting of course!). If the top one was bad the thermostat would apply the power to it but it never goes on. It would always be on never switching to the lower. I eat my original words.

See eat my words statement above.

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Assumptions: Two elements, an upper and a lower. Temp setting the same on both. Same thermostats providing the same upper and lower limit swing.
Diagram: http://home.howstuffworks.com/water-heater1.htm
State: No water being drawn. Tank just sitting.
Colder (denser) water will be at the bottom of the tank. Heat rises. When the temp at the bottom of the tank goes below the lower thermostat limit, the lower element goes on until the water at the bottom is up to temp. Element goes off. Top element never comes on.
State: Hot water being drawn lightly/intermittently.
Hot water being drawn from the top of the tank. Cold water being fed into bottom of tank from inlet/dip tube. When the temp at the bottom of the tank goes below the lower thermostat limit, the lower element goes on. Providing the demand is not high, the upper element will not go on because the low limit of the upper thermostat is not reached. Bottom water reaches temp and thermostat shuts off. Top element never comes on.
State: Hot water being drawn heavily like shower or hot water wash.
Hot water being drawn from top of tank. Cold water inlet being fed to bottom of tank via dip tube. Bottom element goes on. Demand is faster than lower element can heat. Lower limit of upper thermostat is reached. Upper element goes on. Lower element turns off. Upper element stays on until the water in upper tank is up to temp. Upper element goes off. Lower element goes back on until water at bottom of tank is up to temp.
I'm no plumber, heating guy or any of that. This is just my understanding.
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If they are both the same age I would think the bottom one would go first. It goes on first since cooler water will be at the bottom of the tank. See diagram at http://home.howstuffworks.com/water-heater1.htm

My guess is one of two things. The bottom one is bad. If the top was bad, that would try to turn on. When the top turns on the bottom shuts off. Since the top is bad, water never heats and bottom never comes on.
No experience personally but I have heard of cases of a cracked/broken dip tube inside the tank near the top. Cold water gets fed to the top of the tank instead of the bottom.

Turn the breaker off then run a hot water tap until it is cold. Much faster than waiting for it to cool.

Open hot water faucets and the pressure relief valve too.
and

If you have high lime/calcium in your water, I had a personal situation where it built up around the lower element to the point the bad element would not come out of the hole. When i finally got it out by breaking it, the bottom of the tank was full of white crud. Nightmare.

Go get a cheap AC tester. You'll find other uses for it. FYI, don't get a cheap analog/digital multimeter. It will probably be low impedance and give you inaccurate readings in some cases.
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wrote:

The bottom goes because it is usually most affected by sediment
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snipped-for-privacy@aol.com wrote in

Good point! Thanks.
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Tennessee Valley Authority?

I don't know what the symptoms are when the top element is bad, but when I had the same symptoms as you, it was the bottom element. I figured that out by using a volt-ohmmeter. Sometimes called a multi-meter. They have them at Radio-Shack for under 20 dollars. If I recall what they sell, I wouldn't get the cheapest little one with a needle movement, but the next one up, which happens to be digital.
(Nothing wrong with an "analog" meter, one with a needle, but the cheap one they sell is just too small. Digital meters do have advantages, though, such as usually auto-polarity. Even when measuring a DC voltage, like testing a battery, you don't have to have the red on positive and the black on negative. It will just show a negative sign if you connect it backwards. Some digital meters have auto-ranging, but one can live without that....)

As someone said, if you take the cover panel off (to check which one you need, and if you need the heater or the thermostat -- neither are hard to replace) you'll see if you want screw in or bolt-in.
OTOH, if you went to a Rheem dealer, he would know. OT3H, who are you going to believe, the dealer or your own eyes? I doubt the dealer would make a mistake, but if you see 4 screws arranged in a square around the element, it's bolt in. If there are no screws, it's screw in. That is, the whole element screws in.
The easiest way to check the element to see if it is bad is to turn off the breaker for the water heater, use the scale of the voltmeter that is higher than 220 volts AC to measure the voltage between the two screw terminals on the element (always measure voltage before measuring resistance, to see if it is safe for the meter to measure resistance).
When you see that there is no voltage, use the continuity setting, the buzzer, to see if the heating element is continuous from one screw to the next. Aha, but since the water is fairly cold by now, both thermostats may be on, so if one heating element is bad, it is still in parallel with the other heating element maybe, probably, so you need to disconnect one wire from the heating element, and then measure the continuity of the heating element. It will show as bad now if it is bad. You can also use any of the ohm scales, especially the lowest one, to measure ohms. If the heater is good, it will show zero or close to it. If the heater is bad, it will not change from when the probes are not touching anything. The reading will be blank, or dashes, or something like that. You can verify the meter is working by connecting its two probes right together and it should say zero or very close to zero.
If it is not the heating element, again (remember that the power is still off. At least you were supposed to have turned it off) then put the two probes on the two screw connectors of the thermostat, which is a square thing with a dial on it right next to the element. Same thing as above. Since the water is cold now, at least cold enough that the heater should be heating, the thermostat should be closed.

Because I didn't know I could get heating elements at a hardware store, I got up early and went to the AOSmith dealer in town (I had an AOSmith heater iirc) and he sold me what I needed, and because I talk a lot (as you can see here) I said something like this, and he said there was no need to drain the tank, which is time-consuming and wastes water and hot water. IIRC, he had me turn off the main water supply to the house, hot and cold, then open the lowest HOT water faucet in the house, the basement sink. Some water will come out, but after a few minutes, no more will. Because if new water can't get in the other end, water can't come out this end. Air pressure, growing vacuum, etc.
Then go to the water heater, have the new element ready, the wires disconnected from the old element, remove the element and as quickly as possible put the new element in and start screwing it in or bolting it on.
That's what I did and I didn't lose more than 2 or 3 tablespoons to a quarter cup of water. Not positive because some went into the insulation inside the water heater, but it was very little. Because of turning off the water to the house and opening the hot water faucet, there was no pressure so the water idn't come out with force and there was no problem putting the new element in, which there would have been I guess if the water pressure were on.

You could use the USB port. Just go into DOS, or Command I guess it is called, and type "voltmeter". That will measure the voltage at the first USB port. Wait a second.... No, that was just a dream I had once. You need a separate meter.

It's the air conditioning where this happens because there are two breakers powering the AC, but you really shouldn't be doing anything electrical more than changing a lightbulb wihtout a meter. Maybe you turn off the breaker and a helpful family member turns it back on. Maybe you develop geriatric dyslexia and turn off the wrong breaker. You need someway to see the electricty, and the meter is the best way.
Never measure ohms until after you have measured voltage. There should be no voltage when you are measuring ohms.

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loved the DOS joke... lol! I bought two elements today, called rheem customer support and they told me what to get, i also bought the tool used to screw them in (since they are screw in). Figured id replace bouth.
I was thinking "the heater is 12 years old, ill just buy a new one" but the installed price was like over $700, so I fugured I would try this one first...
Yeah, my dad told me about the "quick draw" mehtod, but all the same i think I will drain it, in case there are any sediments...
if you guys dont hear from me by this weekend, it went well... if it was a disaster, ill prob be back. thanks again! Jazz Mann
PS... yes, tennessee valley authority. Honestly, he has worked there my whole life and retired recently,... and still, to this day, I cant tell anyone what my dad does or did... i always jut say "He works for TVA" that either stumps them or they nod in understanding... either way they stop asking.
mm wrote:

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12 years ain't that old so replacing the element was probably a good call.
I would definitely drain it before working on it, in doing so you might also get rid of whatever it was that caused the problem - like all that rust and mineral deposits.
Watch the drain, sometimes they don't want to shut off after you open them, might just try to flush the drain with water if it doesn't want to close all the way - sometimes rust and or minerals get caught in the valve.
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wrote:

Saw a guy change a pressure relief valve doing "quick draw" as you call it. Neat. With risk of soaking stuff due to lack of personal experience, I drain. And like said, suppose to periodically drain from valve anyway to extend lower element life.
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success! Called rheem, asked them exactly what to buy at home depot, installed it in only a few hours (would have been less than an hour but my neighbor took his time bringing my screwdriver back that i lent him lol). I did drain, and, as everyone suspected, it was the bottom element (but i replaced them both). thanks guys! jazz mann
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wrote:

OOops. If the heater is good, it will show a low value, but not zero.
With analog meters, where the ohmmeter part has to be "zeroed", and where different scales zero maybe a bit differently, I got used to thinking, in places where the actual value wasn't critical, where I was using the meter to decide if there was continuity or not, of anything close to zero as zero.

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I'd get your dad to help plumb a natural gas line and put in to new water heater. Electric water heaters are inefficient. Ofcourse, you could also forget the element, and put a solar panel on the roof to put hot water in there.
Jazz wrote:

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