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What is a hot water 'Tempering Valve' ?

A tempering valve is designed to protect you from being scalded by hot water when it comes out of a faucet. A Tempering valve works by mixing hot and cold water to achieve a desired temperature from a particular outlet. If water is delivered too hot, scalding can occur and if stored too cold, bacteria can grow within the tank. A Tempering valve allows hot water to be stored at a high Temperature inside the tank and then mixed with cold water before reaching your kitchen sink, shower or bath.

Common Tempering Valve faults & possible causes

1. The desired mixed water Temperature cannot be obtained or valve is difficult to set

- Inlet temperatures are not within specified limits

- Hot and cold suppliues are reversed

- Strainers contain Debris

2. Temperature fluctuations or changes over time

- Fluctuating supply pressures

- Strainers may contain debris

- Inlet Temperatures may have altered due to seasonal temperature changes.

3. Either Full hot or cold water flowing from outlet fixture

- Hot and cold supplies are reversed

- Strainers are blocked by debris

4. No water flow from the outlet

- Hot or cold water supply failure

- Strainers are blocked by debris

5.Flow rate reduced or fluctuating

- Inlets blocked by debris

- Fluctuating water supply pressures

6. Mixed water Temperature does not change when adjusted

- Hot & cold supplies are reversed

7. Hot water flows into cold water

- Non return valves may be blocked by debris

8. Noisy Valve

- Water Velocity above requirements.

Hot Water Tempering Valve maintenance

- It is recommended the valve is checked annually to ensure it is working correctly. In areas with poor or unknown water supply quality, it is recommended the valve is checked more frequently.

- It is recommended the valve should be checked at the same outlet as was used for the commissioning of the valve.

- The tempering valve itself cannot usually be serviced, if the valve were to malfunction or fail the entire valve will need to be replaced.

If you think your tempering valve is faulty or needs attention, contact our friendly team at The Hot Water Company on 0508 367 468 or visit

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