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Water heater sizing for Nursing Home--Any practical calculators?

JUGHNE Member Posts: 11,102
I have tried several on line, some come up with same or larger than existing.
Existing is working fine, want to change proactively before failure.
Was sized for 1971 usage, 1997 change out was based on that sizing.
Runs at 140 tank temp, mixing valve set at 115 max output, recir line.
Short cycles until tub time, then may have a long cycle.
Want to replace with HTP Phoenix.

Looking for friendly calculator on line.
Also the recovery gain/increase by using temp/mix valve.
I can post all the numbers if someone is into this.


  • hot_rod
    hot_rod Member Posts: 22,468
    Did you try the Lochinvar Toolkit? It has tank sizers and drawdown calculators.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Zman
    Zman Member Posts: 7,605
    On existing setups I have found data logging to be the way to go. If it has it's own gas meter you can log the pulses over time.
    For a couple hundred bucks you can log run time using one of these and a state logger http://www.onsetcomp.com/products/sensors/csv-a8
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    JUGHNE Member Posts: 11,102
    Thank you, I did find the Loch calculator and come up with a number.
    HTP factory rep gave me some good advice also.
    So will go with 199,000 input/119 tank.
    The main factor in this is the tub which can hold up to 80 gallons.
    The insulated reservoir holds 55 gallons.
    Resident is placed in the tub and the 55 gallons dumps and another 20-25 gallons added.
    Then reservoir is refilled during the 30-45 minute bathing time.
    Could be a bath every 45 minutes.
    If the reservoir refill was put off for 15 minutes of recovery time then demand would not be as great. But that takes training and sometimes that will not happen.
    Thanks for your input.
    I'll pull the trigger on this probably tomorrow.