How Do Anti-Scald Devices Work?

anti scalding device

An anti-scald device is a simple yet highly effective way to protect your family from burns caused by hot water. Because not all anti-scald devices work the same way, it helps to understand the differences before you buy.

anti scalding devicePressure Balance Valves

Scalds often happen when the cold water pressure suddenly drops, such as when the toilet is flushed and the water in the shower turns hot. The simplest anti-scald devices prevent this by maintaining a balance between the hot and cold water pressures. They contain either a diaphragm or piston that responds to changes in water pressure. When the cold water pressure drops, the piston moves to reduce the amount of hot water leaving the fixture.

While these models are the least expensive, they need to be calibrated after installation. Accurate calibration is essential for correct operation. If you change the temperature setting of your hot water heater after the anti-scald device is calibrated, the device must be re-calibrated to work reliably.

Thermostatic Mixing Valves (TMVs)

Instead of controlling the water pressure, a thermostatic anti-scald device controls the temperature of the water leaving the fixing. The device mixes hot and cold water inside a chamber that contains a thermostat element. This element expands and contracts in response to temperature changes. As the temperature rises, the element expands to limit the amount of hot water entering the chamber.

With one of these valves, you can reduce the water volume without affecting the temperature, making it easier to save water. These valves don’t need to be calibrated, but they’re also more expensive than pressure balance devices.

Combination Valves

These anti-scald valves use both pressure balance and thermostatic mixing mechanisms to provide maximum protection from scalds. They use a mixing chamber to control the temperature of the water leaving the tap. Additionally, when there’s a sudden change in the hot or cold water pressure, the valve moves quickly to balance the pressures.

For guidance on choosing anti-scald devices for your home, contact us at Reliance Home Services anywhere in Greater Los Angeles.

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