I have a rheem heater M/N 81V40D how do I change the anode?

https://www.youtube.com/watch?v=u6w88TXMbg8

Copy following links to identify and troubleshoot leaking water heater:
http://waterheatertimer.org/Leaking-water-heater.html
http://waterheatertimer.org/How-to-install-gas-water-heater.html
When tank rusts out, it will get pin holes, and water will leak out of top.
Replace water heater.
http://waterheatertimer.org/How-to-maintain-water-heater.html
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There are two types magnesium anode.
1) Hex-head that screws into separate port on top of tank, and comes either 44" long or 12" sausage links.
2) Combo-anode that connects to Hot water nipple, and comes in solid or combo.

Contact guys at following link to purchase anodes
http://www.waterheaterrescue.com/pages/WHRpages/English/OrderPages/XCart/sales-through-XCart.html

General instructions and types of anodes
http://waterheatertimer.org/Replace-anode-rod.html

Rheem 'preferred parts'
http://waterheatertimer.org/pdf/2011_Rheem-anode-rods.pdf
Purpose of resistorized anode is supposedly so magnesium performs as well as aluminum.
Rheem however had 'resistorized elements' years ago, and that turned out to be promotional gimmick so people would buy rheem-brand products.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Open following links for water heater troubleshoot:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Is this a tank-type water heater?
Anode rod is usually replaced:
http://waterheatertimer.org/Replace-anode-rod.html
Tanks that have odor, because of bacteria reacting with anode metal, can be flushed with 2 pints of hydrogen peroxide.

Question posted under Rheem water heater.
Model number does not describe water heater.
Model number posted in question does not appear at Rheem, and does not appear in a web search for water heaters.
Here are options:

1) Add a comment and describe water heater in detail so expert can access more information

2) Contact Rheem.
http://www.rheem.com/Contact.aspx

3) If this is tank-type water heater, the anode is located on top of heater.
Look for 1-1/6" hex nut located under a plastic plug.
Some anode rods are connected to the hot-water nipple.
Sometimes the top cover has to be removed to find anode hex nut.
I have used impact wrench on anode, and could not remove in some cases.

4) More resources:
http://waterheatertimer.org/Replace-anode-rod.html

I don't know how much they are, but you can buy replacement parts on amazon, here: Amazon com 81v40d replacement I hope this was helpful. Have a nice day

Generally tank odors are bacteria reacting with anode rod.
Make sure odor is isolated to water heater, and on hot water line only so you know water heater is best suspect.
Change anode rod.
http://waterheatertimer.org/Replace-anode-rod.html

Your plumber will know all about anode rods and will have tools or impact wrench for removing old anode rod.

Anodes are located on top of water heater.
There are no hard fast rules for location, either by model number or brand.
Most times the manual is likewise vague.
1) There is hex head visible on top of tank.
2) Hex head is located under a plastic cover
3) Hex head is located under metal top, so remove screws holding top, and lift top off to view hex head
4) Anode is connected to hot water nipple.
5) With 9-12-15-and lifetime tanks, you can have 2 anode rods, and each has to be made of same material to work properly. Usually magnesium-aluminum instead of aluminum.
But if you inspect and change anodes frequently to prolong life of tank, then one is as good as the next.
http://waterheatertimer.org/Replace-anode-rod.html

Open following links shows Rheem anode rods
http://waterheatertimer.org/pdf/Rheem-Ruud-anode-rods.pdf
http://waterheatertimer.org/pdf/Rheem-Ruud-water-heater-parts-guide.pdf
Tech resistor anode rod has resistor added to prolong life of anode.
You can cut rod off to fit size of tank. You want anode 5-6" from tank bottom so sediment build-up doesn't reach anode.
Anodes are standard 1-1/16" hex head.
http://waterheatertimer.org/images/Water-heater-anode-006-200.jpg
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

Add a comment with your experience so others with same-similar problem can benefit.

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

You can find age of water heater from serial number located on label on side of tank.
Label also shows tank size, and tank wattage and element wattage

http://waterheatertimer.org/Figure-Volts-Amps-Watts-for-water-heater.html
http://waterheatertimer.org/Water-at-bottom-of-water-heater.html

Serial number decoder:
http://waterheatertimer.org/pdf/WaterHeaterSerialNumberDecoder.pdf
For example Rheem serial number 0790...
First 2 digits are month 07 July
Next two digits are year 1990

Rheem site does not show 81v40d
http://www.rheem.com/products/tank_water_heaters/electric_water_heaters/