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# Rinnai RUCS75i Fan Frequency Hz Question (Newbie)

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Member Posts: 2
So I am a newbie to the site and tankless water heaters and I am fascinated with the technology. I self-installed a Rinnai RUCS75i with a Control-R wifi controller. The app provides ability to collect codes, which includes Fan Frequency. Can I calculate BTU's from fan frequency Hz?

Sorry if this is a stupid question and my be why searching this forum failed to produce anything.

• Member Posts: 23,428
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Probably not, without access to a calibration curve -- and even then its kind of doubtful.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 7,572
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If the motor is 60 Hz, they likely have it set up so that full output is 60 Hz.
Like Jamie said, without the curves it would be difficult to tell more.
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein
• Member Posts: 2
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Measuring the Hz is what I thought too, but the app fan frequency reading is 384 Hz?? I believe the app is incorrect...just thought I'd ask to confirm my thoughts.

Thanks
• Member Posts: 23,428
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The app might be correct -- and might be measuring a fan blade passing frequency, rather than the drive current frequency. How is the app hooked up? You'd still need curves, though...
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 7,572
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Come to think of it, burner freq drives often spit out numbers like that. They are usually smaller motors and the 3 phase is replicated from a single phase power source. I've never been able to get a clear answer as to what the numbers are actually measuring.
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein
• Member Posts: 1,047
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, You need a hobby! All modulating appliances gas consumption tracks off the air supply, so you may be able to do it, with the curves, which Rinnai does not supply. 800 621-9419 is the Tech number. Make sure you register the warranty with the Wireless function.