I have a Model PH-28ROFN. The control pad reads 120 as it always has. When I turn on the faucet the code C2 11 flashs in sequence. No hot water is available. Any ideas please. Jerry Averill

You have a hot water leak. If you turn off the water your system should hold pressure. If you turn a faucet on and it doesn't spurt or if it draws air in that is a sure water leak.

Copy following link:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

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

follow this steps and fix it. God bless you
Drain a tank:

1. Shut off power at the electrical service panel and post a sign warning others not to turn it on.
2. Close the cold-water supply valve and open a hot-water faucet somewhere in the house (to speed draining).
3. Attach a garden hose to the drain valve and run it outside the house.
4. Open the drain valve and allow all water to drain out.
5. To refill the tank, close the drain valve tightly and open the cold-water supply valve. Also open a nearby hot-water faucet. When a steady stream of water flows from that faucet, the tank is full and the faucet can be closed.
6. Once the tank is full, turn the electrical power back on

Test and replace a heating element:

1. Turn off power at the electrical service panel and post a sign warning others not to turn it on.
   
2. Remove the access panel on the electric water heater.
   
3. Disconnect one of the element wires and set a multimeter to RX1000 (resistance times 1,000). Touch one probe to an element mounting bolt and the other to each element terminal screw, in turn. If the tester displays anything but infinity ( open circuit), replace the element.
   
4. If necessary, set the multimeter to RX1 and touch the probes to the terminal screws. If there is any resistance reading at all ( closed circuit), then the element is good. If not, replace it. Both upper and lower elements are tested in the same manner.
   
5. To remove the element, first drain the heater.
   
6. Disconnect the remaining element wire. Remove the mounting bolts holding the element in place. Remove the element.
   
7. Replace the heating element with one of the same model, shape, and rating. Make sure you also replace any installation gaskets.
   

Test and replace a high-limit cutoff:

1. Disconnect power to the heater at the electrical service panel and post a sign warning others not to turn it on.
2. Remove the upper access panel and push the reset button.
3. Replace the access panel and turn the power back on. If the water is hot, the reset was the problem. If not, you'll need to turn the power off again and reopen the access panel.
4. Use a multimeter to test the cutoff terminals for continuity. If faulty, replace with an exact replacement part.

Before calling service technician, open following link for troubleshooting resources, including possible manual, and Rheem chat.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
Rheem usually asks you to call local service technician.

There are many factors that cause problem you describe: bad PC board, sensor problem, loose wires, crossover in single-handled faucet, lime build-up in heat exchanger, clogged water filter.
The remote control might give you an error code. Error code is a starting point for troubleshoot.
Error code on one unit can have different cause than same error code on different unit.

Read manual for required maintenance.
Tankless require yearly maintenance.

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The only Whirlpool electric heater I know with control board is Energy Smart electric:
Open following link to identify product and download sample manual:
http://waterheatertimer.org/Whirlpool-Energy-Smart-electric.html

First of all, the water heater is always full of water.
When you turn on hot water tap, hot leaves top of tank, and new cold water immediately enters bottom of tank through the dip tube. The tank never has air pockets as these would damage tank as explosive steam would fill that pocket ... remember they used to run locomotives with steam power.
So the tank is always full of water, and you know that since no air comes out of the hot water faucet.
http://waterheatertimer.org/How-it-works.html

You did not say if this is new heater, or if heater was working correctly and stopped functioning.

What you describe does not sound normal.
I suggest calling Whirlpool at 1-877-817-6750.
You need to have serial number and model number from label on side of tank so product can be fully identified by Whirlpool.

If control board is bad, they will know and will sell you new board.
Installation is easy, and wires are color coded.
Replacement comes with instructions.

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

Add a comment for more free help.
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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.

Double check your incoming power supply to the heaters main control panel with a voltmeter.

Inspect the power supply inlet fuses and replace if necessary.

Remove and clean the inlet water supply filter; impeded water flow will not activate the flow switch.

Measure the water flow from each hot-water faucet. You need at least .75 gallons a minute.

Inspect the water flow control turbine. Mineral buildup on the blades will stop it from spinning.

If this is a new installation, make sure that the hot and cold-water lines are not crossed.

Test your plumbing for a cross connection. Turn off the water supply to you heater. Open all the hot

water faucets. If you get a steady steam of water from any of them, you have a cross connection that needs to be remedied. When all else fails, Rheem's customer support team is great. They have always help me with the most technical questions, even on older and outdated products.

For images and product information
For manual


You checked ohms, did you check for 240V across lower element when lower element is turned on?

Energy smart electric water heater has a control box on top of unit. Water heater does not have typical thermostats that can be tested and replaced. Temperature sensors located above each element send information to control box through small black and red wires. Temperature sensor sells for about $40, but there is no test listed that shows how to determine when sensors fail.

Potential problems:
-Temperature sensor is not reading correct temp
-Control box not processing correct temperature information
-Selector on control box set to 2, 3 or 4
-Thermostat temp on control box set lower than 120 degrees F
-Sediment build-up starting to surround lower element so water doesn't circulate (see if drain valve runs full-open

actually, does it give you a big rumble? if it does, then your problem is that the meter's btu's are not high enough and there's too litle gas getting to the heater so it's blowing itself out, basically. you'll need to call your gas provider and ask for them to bring in a higher btu meter. around 220,000 btu meter is best, so your furnace and gas stove(if you have one) dont take to much gas themselves, meaning dont get a 180,000 btu meter, because it would only be able to supply the heater.

check your gas pipe size. make sure you have enough gas running to the unit. also turn all your faucets on hot and turn off the cold water to the heater and see if you get any water out of the hots anywhere, that could mean that you have a cross connection.

http://www.rheemtankless.com/content/tankless/rheem/help.shtml

This is there website.Above.
Use the live chat to ask them, the code you listed does not seem to correspond to there code list, the only code that does is code 76,
which is a problem with the remote control not talking to the unit.
So your best bet is to tell them the error.