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2. Backflow prevention device - Wikipedia

   en.wikipedia.org/wiki/Backflow_prevention_device

   Backflow prevention device. The simplest, most reliable way to provide backflow prevention is to provide an air gap.An air gap is simply an open vertical space between any device that connects to a plumbing system (like a valve or faucet) and any place where contaminated water can collect or pool.

3. Aquastat - Wikipedia

   en.wikipedia.org/wiki/Aquastat

   If the thermostat is calling for heat, the boiler will fire until the high limit is reached, then shut off (even if the thermostat is still calling for heat). The boiler will re-fire if the boiler water temperature drops below a range around the high limit. The high limit exists for the sake of efficiency and safety.

4. Reduced pressure zone device - Wikipedia

   en.wikipedia.org/wiki/Reduced_pressure_zone_device

   Some normal water use conditions may cause short episodes of discharge (this is why check one has a minimum passing value of relief +3. It is designed to handle the pressure fluctuations). In the case of the upstream check valve passing, the differential pressure (higher supply pressure compared with the lower chamber pressure) causes any flow ...

5. Automatic balancing valve - Wikipedia

   en.wikipedia.org/wiki/Automatic_balancing_valve

   In a variable primary chilled-water system, the design flow rate is determined by the water flow velocity in the tube of the coils. At typical conditions, 6–7 feet per second (1.8–2.1 m/s) Maximum 12 ft/s (3.7 m/s) Minimum 1.5 ft/s (0.46 m/s) (based on a Reynolds number of 7500) Minimum flow is typically 50% or less of the design flow. [1]

6. Water detector - Wikipedia

   en.wikipedia.org/wiki/Water_detector

   A water detector is an electronic device that is designed to detect the presence of water for purposes such as to provide an alert in time to allow the prevention of water leakage. A common design is a small cable or device that lies flat on a floor and relies on the electrical conductivity of water to decrease the resistance across two contacts.

7. Tankless water heating - Wikipedia

   en.wikipedia.org/wiki/Tankless_water_heating

   Larger whole-house electric units may require up to AWG 2 wire. In gas appliances, both pressure and volume requirements must be met for optimum operation. Start-up delay: There may be a longer wait for hot water. A tankless water heater only heats water on demand, so idle water in the piping starts at room temperature.