Rinnai Tankless Water Heater Altitude Derate Chart

toeknee

I just got this info from Rinnai support, just wanted to share it here as I couldn't find it anywhere. This may help a person or two out down the road with de-rating these specific models from Rinnai.



There was also an interesting and informative discussion on derating gas appliances started by @Zman a number of years back.
https://forum.heatinghelp.com/discussion/151147/altitude-and-deration/p1

that conversation went on and off for over 3 years I believe ha!

I dont know what this chart I received converts to in percentage because Rinnai uses a range of altitude for each deration for these appliances. And I'm not sure if these tankless water heaters are forced induction or not, but anyway, as many have said, use the documentation provided by the engineers who designed that specific equipment.

Zman

I wonder how much actual research they put into these numbers. Lochinvar and Viessman do real testing at altitude and have very exact derations. This chart looks like they just used 4% per thousand and walked away.
If I see a Rinnai at altitude, I may just need to clock the meter out of curiosity. If these derates are correct, given the low incoming water temps, a 199 model could barely support one shower.