Sanitary Fixtures, Appliances and Water Heating
This domain covers the selection, installation and servicing of WCs, basins, sinks, urinals, baths, showers and water heaters. Questions test fixture set-out, flushing volumes, geyser types, safety devices and energy calculations.
Fixtures and appliances
Know close-coupled and wall-hung WCs, wash basins, kitchen sinks, urinals, bathtubs and showers. Dual-flush WCs commonly use about 3 L and 6 L; sensor urinals reduce flushing. Each fixture needs an accessible trap, a stop valve and a secure connection. Wall-hung fixtures need a suitable frame and fixing. Appliances such as washing machines and dishwashers need a tap, a trap connection and a backflow-protected supply.
Water heating
Electric storage geysers, instantaneous heaters and solar water heaters each have different pressure and temperature limits. Fit a temperature-and-pressure relief valve on a closed storage heater, an expansion arrangement where required, and a drip tray or safe discharge. Keep the thermostat and sacrificial anode in service; hard water causes scaling and shortens element life. Insulate hot-water pipes to cut standing losses.
Worked example
Heat 100 L of water from 20 °C to 60 °C. Q = mcΔT = 100 × 4.18 × 40 = 16,720 kJ. Since 1 kWh = 3,600 kJ, energy = 16,720 ÷ 3,600 ≈ 4.64 kWh. At 100% efficiency this takes about 4.64 kWh; a real geyser takes longer because of losses and element rating.
Traps that cost marks
Never block or remove a T&P relief valve; do not install a storage geyser horizontally unless rated for it; do not discharge the relief valve to a closed space; do not undersize the electrical circuit; and do not ignore the pressure rating when connecting a geyser to a mains-pressure system.