Code P1 is flasing - Rheem Tankless Hot Water Heater Rtg-74pvp-2 7.4 Gpm

Go to the manufacturer's website and enter your model number and click on "Support" and there should be a FAQ's or other support options for you. Otherwise the website may have a "Contact" phone number to call or a way to Chat online.

are you sure it is E1 not P1?
Error P1 is not enough water flow.
Clean water filter located on cold water inlet at top of cold pipe when cold enters unit
Test single handle faucets for crossover
Check if faucet can fill 1 gallon can in 30 seconds.


http://www.palomastore.com/paloma_error_codes.html

P1 clean water filter:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#filter

Gene

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

Copy following link for troubleshoot resources Rheem/Paloma tankless:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://waterheatertimer.org/images/Rheem-service-valves.jpg
http://waterheatertimer.org/Crossover.html

Error P1 is not enough water flow.
Clean water filter located on cold water inlet at top of cold pipe when cold enters unit
Test single handle faucets for crossover
Check if faucet can fill 1 gallon can in 30 seconds.

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

P1 error code is not enough water flow to operate the unit: increase water flow to unit.
http://waterheatertimer.org/pdf/Rheem-Error-code-P1.pdf
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Error codes are considered start-point for troubleshooting.
Page 18 of maintenance manual shows how to clean water filter monthly.
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

Other causes can include faulty sensor, clogged in-line filter, clogged water softener, sediment in pipe, sediment at elbow, bad check valve, water leak, etc.

Take a moment and rate answer:
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.
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Before calling service technician, open following link for Rheem troubleshoot resources including Rheem chat:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Error codes are considered start point for troubleshooting, and can sometimes mislead.
Error P1 is 'not enough water to operate the unit:'
http://waterheatertimer.org/pdf/Rheem-Error-code-P1.pdf

This problem can be caused by plumbing problems such as crossover, or clogged water lines, or dirty water filter, or clogged water softener, or temperature of unit set too high. Or combination of these problems.
Remember if temperature is set very high, then more cold water is used at the faucet. This means less hot water is drawn through the tankless water heater, so the flow rate may drop below activation threshold.
http://waterheatertimer.org/Crossover.html
http://waterheatertimer.org/Low-hot-water-pressure.html

just clean shower head or faucet with CLR to increase water flow. I have same problem

P1 is reportedly defective check valve that can cause water flow to decrease, and tankless not heat water smoothly. But can also be other causes, or combination of causes. Call service technician, contact Rheem, or replace check valve and see if problem solves. Then add a comment with solution so others can benefit from your experience.

Open following link for Rheem/Paloma/Richmond/Ruud tankless troubleshoot resources including error codes, self help, manuals, parts links, tips, and contact information.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

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.

1) I cannot find Rheem error code P1
http://www.palomatankless.com/owners/homeowner+trouble.lasso
http://www.palomastore.com/paloma_error_codes.html

2) BOSCH does not show P1 either:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx

3) Best I could find is that folks with P1 error code report tankless fires for short period, and then turns off.
This implies air, fuel or vent problem, and can be internal, external or combination.

4) P1 appears frequently on control board descriptors, which might imply the error is control board malfunction.

5) Call Rheem 1-800-432-8373, and then add a comment to this thread and let folks know what you discover.

6) I will also call Rheem when time permits, and post what I discover.

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.

Water inlet temperature to the heater is the same as preset on the controller.
I had this happen to me becouse I have a solar tank with temp of
135 farenheit.
Once I bypassed the sollar tank..no problem