What temperatures are possible with a thermostat valve?

Quick Answer: A thermostat valve always blends hot and cold water, so it can’t provide pure cold like a pressure balance valve. Under normal supply conditions, you can expect shower temperatures between ~68 °F and ~120 °F (20–49 °C). The cartridge can sometimes be adjusted to raise the maximum setting slightly, but there is an inbuilt safety limit of 120 °F (49 °C), so water will not exceed that point.

Incoming Water Temperatures (Factory Test Conditions)

• Cold water supply: ~57 °F (14 °C)
• Hot water supply: ~158 °F (70 °C)

These are the reference supply conditions used by our factory when testing.

Mixed Water Temperature Range

• Lowest mixed water temperature: below 68 °F (20 °C)
• Highest mixed water temperature: ~116–120 °F (47–49 °C)

How Incoming Cold Water Affects the Range

The coldest achievable mixed water temperature shifts depending on your cold supply:

• If your cold supply is 57 °F (14 °C), the coldest mixed water will be just under 68 °F (20 °C).
• If your cold supply is 50 °F (10 °C), the coldest mixed water will also shift lower, closer to 61 °F (16 °C).
• If your cold supply is 65 °F (18 °C), the coldest mixed water will shift higher, closer to 73 °F (23 °C).

This means the valve adapts to your home’s actual incoming water conditions—the “floor” of your temperature range rises or falls with your cold supply.

Maximum Hot Temperature

• Regardless of how hot your incoming supply is, the hottest mixed water is capped at 120 °F (49 °C) for safety.
• In some cases, the cartridge can be adjusted to shift the maximum setting slightly within this limit. For detailed guidance, please contact our customer service team with your valve information.

Key Takeaways

• Thermostat valves always deliver mixed water, never pure cold or pure hot.
• Normal range: ~68 °F to ~120 °F, depending on incoming supply conditions.
• Coldest available temperature shifts with your cold supply.
• Hottest possible temperature is limited to 120 °F (49 °C) for safety.
• Cartridge adjustments may be possible—reach out to customer service for support.