Mixing Valve Calculator
Mixing Valve Calculator
Calculate safe hot water mixes to optimize tank storage while preventing scalding.
Table of Contents
Mix Settings
140°F kills Legionella bacteria in under 32 mins.
120°F is the standard safe delivery temperature.
Mix Ratios & Safety
Hot Water Ratio
0%
0 GPM
Cold Water Ratio
0%
0 GPM
Delivery Safety Zone
Safe
Time to severe scald: Safe at this level.
Tank Legionella Prevention
At Risk
Legionella grows rapidly inside tanks set below 120°F.
Why use a Mixing Valve? Setting your tank to 140°F kills bacteria, but can burn skin in 3 seconds. A mixing valve safely blends in cold water right at the heater outlet to deliver safe 120°F water to your taps.
Thermostatic Mixing Valve Formula
Mixing valves blend hot water from the heater with cold inlet water to deliver safe, warm water to fixtures. This allows storing water in the tank at a bacteria-killing 140*F while preventing scalding at tap.
Formula Used
Hot Water Ratio = (Mixed Temp - Cold Temp) / (Hot Temp - Cold Temp)
Reference Quick Chart
| Tank Storage Temp | Cold Inlet Temp | Hot Water Ratio for 110*F Shower |
|---|---|---|
| 120°F | 50°F | 85.7% Hot / 14.3% Cold |
| 130°F | 50°F | 75.0% Hot / 25.0% Cold |
| 140°F | 50°F | 66.7% Hot / 33.3% Cold |
| 150°F | 50°F | 60.0% Hot / 40.0% Cold |
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