That's right, must be Jakura that has a TK3. The Rinnai R75lsi can also deliver 6 GPM at 50F rise but maxes out a 7.5 GPM and a 35F rise. Was the recommendation for a 53 based on Rinnai's online "tankless assistant" that you referenced in another post? Seems to me it's recommendations are a bit undersized; I entered my zip code and one bathroom a got a recommendation for a unit that could handle a bath group and little more.Nope, don't own a TK3... I have a Rinnai R75lsi. Could have "got by" with a 53 but was advised to "upsize"... so I did.
Seems the advice you got to upsize was good. Where have I heard that recommendation before?