Hot and Cold Water Systems in Buildings: Key Concepts
What Determines Water Hammer?
- The cutting time of the liquid mass flow of water. The parameters that determine water hammer are:
- Kinetic energy = ½ * m * v2. A higher speed results in more kinetic energy surge.
- Water velocity
- Pipe length
- Time of valve closure
- Stopping of lift pumps
Measures for Pipes Through Walls and Floors
Always place a pass-through and fill the slack space with a soft and waterproof material.
Maximum Speed in the Network
To avoid noise or vibration, the maximum speed is set to 2 m/s.
Minimum and Maximum Pressure
- 1 Kg/cm2 = 1 atm. = 10 m.w.c. (meters of water column) for common faucets.
- 1.5 kg/cm2 for flushing valves and heaters.
The pressure at any point of consumption should not exceed 5 Kg/cm2.
Data to Determine Storage Tank/Boiler Level
- The type of activity in the building.
- Hot water volume of the different devices, and the total flow per day.
- Cold water temperatures that will be used.
Low Return Water Inlet Temperature
If the return water inlet temperature is low and the output is at the ideal temperature, check the circulation pump.
Circulation Pump Board Characteristics
Maximum flow, maximum gauge height, and power.
Role of the Boiler Safety Valve
To prevent an explosion in the event of failure of temperature controllers.
Using a Return Pipe for Multiple Lines
Yes, a return pipe can be used as a solution for several lines.
Usefulness of the Safety Thermostat
To turn off the burner in case of failure.
Accelerator Pump in Return Line
The pump is installed in the return line and is sized specifically for the return flow; the ducts should be free of obstructions. If we put it in the supply line, it would act like a plug.
Differences Between Hot and Cold Water Pipes
- Insulation
- Cold water pipes are always below hot water pipes.
- Hot water pipes must expand freely at their anchorages, or use expansion loops (lyres).
- Hot water distribution networks exceeding 15m in length must be equipped with a return line.
- Hot water pipes must have circulation pumps.
Basic Elements of a Booster Group
- Suction tank
- Centrifugal pump
- Tank or pressure tank
- Dashboard
Classes of Hot Water Heating
- Direct heating: The heat produced by the power source is transmitted directly to heat the water, which is later consumed.
- Indirect heating: The heat produced by the power source is transmitted through a carrier (water or other fluid), which then heats the water to be consumed.
Basic Components of Hard Water
Calcium and magnesium. Hardness refers to the total content of calcium and magnesium ions, expressed as carbonates, sulfates, chlorides, and nitrates. Carbonate hardness only refers to the content of calcium and magnesium carbonates in water.
Hot Water Savings in Public Buildings
Timed taps (some with sensors).
Generator Consuming Water Pump
If a generator consumes 15 l/fuel, the flow can be calculated as: Flow (l/h) = (Q (Kcal)) / (Change in temperature °C)
Types of Pipes
- Primary (main artery): Larger in diameter; connections to users are not allowed.
- Secondary (distribution): Arising from the arteries, these are smaller in diameter. They constitute the network fabric and provide user connections.
- Connections (branches): Carry water to individual customer premises. They consist of tubes and fittings.
- Installation: Preferably on sidewalks (1 m) or low-traffic road pavement (1.5 m).
- Coating: Layer of fine sand 10 cm above and below.