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Marc, Plumber
Category: Plumbing
Satisfied Customers: 1126
Experience:  Plumbing heating & home maintenance contractor
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I have a Rinnai RUR98i tankless water heater. The technical

Customer Question

I have a Rinnai RUR98i tankless water heater. The technical specifications show a minimum hot water capacity of .26 gpm. My unit doesn't kick on until 1.1 gpm according to diagnostic code 1 on the controller. Why is it not starting at the lower flow rate?
Submitted: 1 year ago.
Category: Plumbing
Expert:  Jed Noble replied 1 year ago.

Hello. My name is Jed. This could be happening because the Rinnai needs to be flushed with vinegar and clear the float switch. If the unit has been in for a while and you have hard water this is most likely the problem and solution.

Customer: replied 1 year ago.
Hi Jed. I installed the water heater a few weeks a few weeks ago and it needed the 1.1 gpm to start from the beginning. I checked the filters and they were spotless. The controller shows the unit is measuring the high flow and it doesn't seem restricted. It just turns on at a much higher flow than it should.
Customer: replied 1 year ago.
Any ideas?