The Tankless Paradigm w/"Virtual Storage Tank"?

DCContrarian

@RickDelta : "Lets take a single 199K tankless unit and set the tankless set temp to 185 degrees F. (@ a max 3 gpm flow demand )

Run its output into a mixer valve (its out temp set to 125 degrees F)

Roughly, doesn't this significantly increase the total available (mixed) hot water capacity (@125 degrees F) over just the single tankless unit at its max flow rate of 3 gpm ?"

This is where your conceptual flaw is. It doesn't increase the total available hot water capacity one bit. This is what several people have been trying to tell you, you keep insisting we don't understand what you're trying to do.

Look at the chart 199Delta.png that you posted. It's right there.

hot_rod

If the Rinnais are keeping their internal buffer tanks at 180, and you are mixing down to 120, here is a calculator from the Lochinvar Tool Kit to calculate additional capacity. I assumed 30 gallons each in the Rinnais? 60F inlet water temperature?

Screenshot 2024-12-07 at 8.42.02 AM.png

hot_rod

With any public use building you really want to have a listed mixing valve that data logs it's temperature condition. Tie it into the BMS also, to log that data.

We had a LegoMix installed at a correction facility. It logs 40 days worth of information.

An inmate tried to sue claiming he was scalded in the shower. The building operator was able to pull the data for that day and time and show the valve never exceeded 120F at any point. Case dismissed.

Liability becomes more of an issue than accurate , for the valve manufacturer and building owner, vs temperature regulation, unfortunately.

Screenshot 2024-12-07 at 8.48.01 AM.png

RickDelta

@hot_rod

Agreed! : )

(This was an early concept pic with plug in numbers)