Choosing a Water Heater (Storage Boiler vs Tankless): Power and Consumption Calculation

Choosing a water heater is not only about brand or price—it’s about matching your hot-water habits to the correct type and capacity. In a plumbing & water systems context, the two main options are a storage boiler (tank) and a tankless/instant unit. A storage boiler is best when you need stable comfort with moderate electrical load: you heat a volume of water and use it over time. A tankless heater is compact and delivers endless hot water, but it requires high electrical power and careful sizing. Start with demand. Estimate how many points may run at once: shower, kitchen tap, and sink. A typical comfortable shower needs about 6–10 L/min of mixed water. For tankless sizing, focus on the temperature rise (ΔT): incoming cold water to your target hot-water temperature. Power can be approximated as P(kW) ≈ Flow(L/min) × ΔT(°C) / 14.3. Example: 8 L/min with ΔT 30°C requires ~16.8 kW—often too high for many apartments. For a storage boiler, choose tank size by lifestyle: 50–80 L for one person, 80–100 L for two, 100–150 L for a family, depending on shower length. Heating time depends on element power (typically 1.5–3 kW) and tank volume. Energy use is mainly the heated liters plus standby losses; good insulation reduces monthly costs. Tankless units have minimal standby losses but may increase peak electricity demand. In a business directory like Fontana, compare installers and plumbing professionals who can verify wiring limits, water pressure, pipe diameter, and safety valves. Correct calculation prevents lukewarm showers, tripped breakers, and unnecessary energy bills.