What should always be provided with instantaneous water heaters to prevent scalding?

The requirement for a hot water temperature limit with instantaneous water heaters is crucial in preventing scalding incidents. Instantaneous water heaters, which heat water on demand rather than storing it, can produce water at very high temperatures. If the temperature is not adequately controlled, there is a risk of delivering scalding hot water to faucets and showers, posing a significant safety hazard, especially for vulnerable populations such as children and the elderly.

By implementing a hot water temperature limit, typically set around 120°F (49°C), the risk of scalding is significantly reduced. This feature allows for a safe water temperature to be delivered while still providing sufficient hot water for typical household needs. It is important for plumbing designers to consider this aspect when specifying equipment to ensure the safety and comfort of the end users.

The other options, while they have their roles in a plumbing system, do not serve the specific purpose of preventing scalding associated with the high output temperatures from instantaneous water heaters. For instance, a pressure relief valve is essential for safety in the event of excessive pressure but does not regulate temperature. An expansion tank helps manage thermal expansion in closed systems, and a backflow preventer is crucial for maintaining water quality by preventing contamination but is unrelated to temperature control