Calculation of a water heater: selection of volume and power (Excel)

Calculation of a water heater: selection of volume and power (Excel)

Which water heater should I buy? What capacity do I need? Calculate in 5 minutes.

This is an Excel calculator for computation. If you haven’t yet decided what kind of water heater you need, start with the guide "How to Choose a Water Heater."

You’re a professional or a DIY enthusiast. You know that selecting a water heater requires considering the number of people, the number of water outlets, and the water temperature. Calculating manually is time-consuming and prone to errors. An error can cost money: if you buy one with insufficient capacity, you won’t have enough hot water; if you buy an oversized one, you’ll overpay.

This calculator solves the problem. Enter your data and get a ready-made answer: the required capacity, heating time, power rating, and cable cross-section.

What it calculates:

For storage type: recommended capacity (liters), heating time at 1.5 / 2 / 2.5 kW (in minutes), and electricity consumption.

For instantaneous type: current, circuit breaker, and cable cross-section. It warns if the power is close to your apartment’s capacity limit.

Reference data: average water consumption rates.

Why it’s convenient:

• Takes into account the number of people and outlets. No guessing needed.
• Shows heating time so you immediately see how long to wait.
• Checks wiring for instantaneous water heaters.
• Protected. Formulas are hidden, so buyers can’t break them.

Who it’s suitable for:

• Professionals — for selecting equipment for clients.
• DIY enthusiasts — for themselves.
• People renovating their homes.

Important: Consumption rates are averages. Instantaneous water heaters are only suitable for a single outlet. Power exceeding 6 kW is only possible with sufficient dedicated power supply.

Format: Archive (Excel + Word). Works in Microsoft Excel and Google Sheets.