Hot Water Mixing Temperature Calculator
Outlet temperature (or ratio) when hot tank water blends with cold supply.
Storing at 60 °C kills Legionella; a thermostatic mixing valve delivers 43–49 °C safely. A 60 °C tank effectively holds ~1.4× its volume of 'shower-temperature' water.
Formula
Hot Water Mixing Temperature Calculator is a free water mixing temperature for HVAC designers, technicians and energy auditors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Hot Water Mixing Temperature Calculator
Outlet temperature (or ratio) when hot tank water blends with cold supply. The calculation implements T_mix = (Q_h·T_h + Q_c·T_c)/(Q_h+Q_c) (ASSE 1017; plumbing code scald guidance). Storing at 60 °C kills Legionella; a thermostatic mixing valve delivers 43–49 °C safely. A 60 °C tank effectively holds ~1.4× its volume of 'shower-temperature' water.
How to use Hot Water Mixing Temperature Calculator
- 1Enter Hot water temperature in °C.
- 2Enter Hot flow in L/min.
- 3Enter Cold water temperature in °C.
- 4Enter Cold flow in L/min.
- 5Read Mixed temperature, Total flow instantly — no submit button needed.
Why use Hot Water Mixing Temperature Calculator?
- ✓Implements the standard formula — T_mix = (Q_h·T_h + Q_c·T_c)/(Q_h+Q_c)
- ✓Reference cited on-page: ASSE 1017; plumbing code scald guidance
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Hot Water Mixing Temperature Calculator use?+
It computes T_mix = (Q_h·T_h + Q_c·T_c)/(Q_h+Q_c), per ASSE 1017; plumbing code scald guidance. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Storing at 60 °C kills Legionella; a thermostatic mixing valve delivers 43–49 °C safely. A 60 °C tank effectively holds ~1.4× its volume of 'shower-temperature' water.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Hot Water Mixing Temperature Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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