Difficult to turn the water heater

Replacing a water heater is no very difficult if you follow the steps.
1. If it is electric turn of the breaker and check to be sure it is the right breaker. If it is gas turn off the valve close to the water heater.
2. Turn off both the hot water and cold water valves
3. Drain all water out of the heater.
4. Disconnect the electric wiring if electric and if gas disconnect the gas line.
5. Disconnect both water lines which may have to be cut depending on how they are connected.
6. Now you can remove the water heater and discard.
7. Place new heater where old one was removed and reconnect both water lines and be sure you have a new pressure valve installed on the water heater.
8. At this point you can turn on water and check for leaks. you should also open a hot water faucet to purge the air out.
9. If no leaks go ahead and hook up the electric or gas lines and if gas is used turn it on and check for leaks using a leak detector or a spray bottle of soapy water and look for bubbles. If no leaks you can go ahead and light the heater according to its instructions.
10. If electric is used turn it on.
11. Take a long hot shower.

The relief valve is supposed to have a 3/4 line leading away and down to 9" from the floor . That said if it is loose, tighten it slightly and then run piping away from the controls.

1) Be careful before you Call Whirlpool 1-877-817-6750.
Be careful what you report so not to void warranty because installation protocol was not followed. Whirlpool will cover gas control valve, and possibly the installation of valve which takes about 15 minutes and does not require emptying water heater.
************So make sure you report installation that is consistent with installation shown in manual.

2) Whirlpool will also answer this same question later today with invitation to contact them.

3) Copy following link to identify gas control valve, and download service manual:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

4) If dirt or debris gets into gas control valve, it will cause it not to work. Such as broken gas line. Debris can enter gas line.
Or if too much pipe dope was used on gas connection, or stray teflon tape got into line and then into valve, or end of pipe got dirty during installation, and then dirt got into gas control.
Take off gas line and use vacuum cleaner to see if something can be removed by suction. Clean up the joints.

5) It appears you have ordinary Honeywell gas control valve on atmospheric vented water heater with 9 year parts-labor warranty..
Unknown error code, so it is hard to look up solution in service manual.
Add a comment if you want expert to look up error code in service manual.

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

1) Never, ever install tankless water heater, unless your wallet is 2" thick and you enjoy nuisance problems and recommended continual maintenance.
2) Add in-line air vent.
http://waterheatertimer.org/images/Air-vent-added-to-return-22.jpg
3) Look for check valve along the line. Look for mixing valve, pressure regulating valve, etc.
4) If you have recirculation system, remove cross-over check valve and see if problem is located there.
5) Contact Rheem. 800-432-8373 They will want model number, serial number, and name of installer. And might recommend contacting installer or plumber.
6) Increase water flow. Check water flow requirement of tankless (.5 gallons per minute activation) with actual flow at faucet.
7) Clean water filter at tankless unit.
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf
8) Crossover at single-handled faucet.
http://waterheatertimer.org/Crossover.html
9) Fix all leaking faucets indoor and outdoor so no air is being sucked in.
10) Bad TP valve on water heater sucking in air each time water pressure pulls on the valve?

Additional resources: No information about air-in-line
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Rusted water usually means anode rod depleted and tank is rusting. Change 570241 anode rod every year or so.
Boiling water could mean bad thermostat causing run-away heating so water is released out of TP valve. Replace 994062 thermostat for 4 gallon.
Leaking water at TP valve could mean bad TP valve: replace TP valve with generic valve from hardware store.
Open link for diagram, parts and replacement information
http://waterheatertimer.org/pdf/Bosch-GL_English.pdf

Water heater burner assembly and combustion chamber probably needs clean and maintenance.
I suggest calling sears service 1-800 469-4663 or plumber.

I'm on Sears/ American/ Rheem/ Reliance etc gas water heater websites most days, and read gas water heater manuals continually.
http://www.sears.com/shc/s/search_10153_12605?keyword=kenmore+power+miser+9+40+gallon+gas+water+heater+gas
http://www.sears.com/shc/s/s_10153_12605_Appliances_Water+Heaters_Natural+Gas

Most people don't fix air conditioning without knowledge going in, but people think water heaters are simpler, because water heaters were simpler a few years ago.
Today, gas water heaters require testing equipment, and specialized tools, plus replacement parts.

Possible problems include: Improper fuel-air mixture, dirty air intake, venting problems, gas control valve problems, air in gas line, low gas pressure, dirty combustion parts, Water condensate dripping on burner, chemicals stored inside same room. Service technician will review all these things during troubleshoot, and you can watch technician and glean information for keeping water heater working longer than warranty.
http://waterheatertimer.org/Replace-anode-rod.html

If repairs are going to cost more than $400, then install new gas water heater yourself same day:
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Upvote the help.
And 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.

If you mean the drain valve, then buy garden hose cap at home center.
Cap will have rubber washer that seals tank.
If drain valve is plastic, the cap may not thread on without sanding down end of plastic drain valve.
Otherwise replace drain valve, which is simple if drain valve is brass, but can be difficult if drain valve is plastic.
Turn off power to water heater: Electric: turn off circuit breaker. Gas: turn knob to pilot.
Turn off water, open bathtub spigot on Hot side, drain water heater, remove drain valve with wrench.
If plastic drain valve breaks while being removed, then 'gently' break out broken part using hammer and big screwdriver.
Buy new drain valve at box store in water heater department.
Put teflon tape on new drain valve threads.
http://waterheatertimer.org/Water-heater-is-leaking.html
http://waterheatertimer.org/Water-heater-will-not-drain.html
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

Add a comment for more free help.
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.

Very simple - call a Plumber. He will fix your plumbing problem, and any foreseen potential problems related to your water leak. He may also suggest replacing your 6 year old water heater. Of course ..... for a professional cost.
However, depending on your time, skills, proper tools, patience and luck, it's easy enough to perform yourself:
1. Switch off the water heater Breakers (220v) in your service panel.
2. Turn off the water supply to the water heater.
3. Attach a water hose to the drain faucet. ( a good time to flush sediment -calcium deposits)
4. Open a hot water faucet to vent (above the level of the water heater drain - kitchen sink)
5. Remove the suspected leak components. (a union connection is a good place to start)
6. Install New pipes -3 wrap all male threaded ends with teflon Tap. Tighten securely - using 2 wrenches.
NOTE: Before refilling - you can turn on the water heater supply valve for a few minutes, to flush out any lingering calcium debris.
7. Shut off drain valve - remove hose. Shut off venting hot water faucet.
8. Turn on water supply valve to fill water heater.
9. Open a hot water faucet to relieve air pressure while filling - preferably the bath tub faucet, it doesn't have a screen that might clog.
10. When water flows without air - shut off tub faucet.
11. Look for leaks.
12. Switch the water heater Breakers on.
Note: 50 gallons should take an hour or more to heat up. Turn on a hot water valve momentarily within this heat up time to relieve thermal expansion. ( the PT valve on your water heater will perform this task if pressures/temperature exceed new water heater tolerances - it's just a precaution to introduce these fluctuating pressures on your fragile 6 year old unit)

These are just basic instructions - assuming you fill in the common sense and work safe steps.
Good Luck - The Skill will only come after trying.

A) Calculate date of water heater manufacture from serial number located on side of tank:
http://waterheatertimer.org/pdf/WaterHeaterSerialNumberDecoder.pdf
Date of manufacture is not date of installation.
Warranty is usually from date of manufacture
Serial number also shows tank size in gallons, tank volts and watts, and whether tank has 1 or 2 elements.

B) Troubleshoot leaking water heater:
http://waterheatertimer.org/Water-at-bottom-of-water-heater.html
Several things can be looked at to see where leak is coming from.
Carefully go over tank pipes and valves to eliminate every suspect.
Final suspect: tank is rusted out.

C) If tank is rusted out, then tank needs to be replaced before it ruptures.
Ruptured tank can cause major damage and water runs until shut off.
To prevent rupture, turn off power to heater, turn off valve located above tank, open tub faucet for a moment to relieve pressure on tank.
Turn on heater only when needed until new tank is installed.
4500 Watt water heater produces 21 gallons hot water per hour.
Shower uses 6-9 gallons hot water. Bath uses 12-14 gallons hot water.

"It is possible to limp along with a failed water heater if the leak is slow and if you turn off power and water when not using hot water. That trick could buy time, possibly up to 3 months. With time, you can consider how to make the system do more for less as well as comparison shop, get competitive bids, etc"

D) Now you're home is safe from damage.
If tank is only 5 years old, it rusted out pretty quick.

There are three things you can do so next heater lasts longer.

1) Learn about anode rods, and inspect anode rod every 1-3 years.
Loosen anode rod before installing new tank so replacement is easier.
http://waterheatertimer.org/Replace-anode-rod.html

2) Attach electrical ground wire between hot and cold pipes to prevent stray current from reducing life of water heater
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html#straycurrent

3) Flush tank each 6 months to prevent sediment
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html#flushelectric

Expansion tank is supposed to stop over-expansion due to pressure.
The check valve will stop over-expansion from pushing pressure back into the supply line.
The real question is what is causing the pressure.
If your TP valve is bad that could cause problem.
If the thermostat is set very high, and there is frequent short-term use of hot water, that can cause heat to build up inside tank.
Solution:
Lift TP valve and let out pressure to see if there is something lodged in the valve.
Be careful of the scalding water.
Let the TP lever down slowly.
Next step would be replace TP valve.
Turn down thermostat to 120, or set to 130-5 if objective is to kill most bacteria.
Last. You might check that your expansion tank is correct for water heater.