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Douglas, HVAC Technician
Category: HVAC
Satisfied Customers: 3089
Experience:  Manufacture Rep for Major Brand, Technical Trainer, NATE
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Rheem tankless water heater not producing hot water. A code

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Rheem tankless water heater not producing hot water. A code comes up and says P1 when you turn water faucet on. When water is turned off it goes back to 120 degrees

Thank You
Hi, I'm Douglas and I am here to help you resolve problems with your heating and cooling equipment.

P1 on a rheem tankless suggests poor water flow, not enough to turn the system on. If you turn multiple faucets on hot, does the unit come on?

is your water pressure low?
Customer: replied 4 years ago.

Hi Douglas,Smile

That did cure the problem by turning multiple faucets on. Will check my regulator valve and adjust if possible.

Thank You


Great, check for blocked strainers incoming and even at the sinks. The system has to have at least 0.66 gallons per minute flow, if it detects flow, lower than that for 5 secondsminutes it will give you the fault. If you have a regulator like you said, you may need to boost the pressure and ultimately the volume will also increase.

I meant to say 5 seconds, I cant seem to edit what I already wrote.

If this has been helpful, please click accept. As always positive feedback is welcome and greatly appreciated.

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