Hot Water System Calculator
Size water heaters and boilers based on occupancy, fixture count, and peak demand. Calculate tank capacity and recovery time.
Enter building details to size hot water system
DISCLAIMER
This calculator provides ESTIMATES for preliminary planning purposes. Results are based on standard assumptions and may not reflect your specific project conditions.
By using this tool, you acknowledge that:
1. All calculations are approximate and based on typical industry standards and assumptions.
About This Calculator
The Hot Water System Calculator helps MEP engineers and plumbing contractors size water heaters, boilers, and storage tanks for buildings across the UAE and Gulf. Calculate hot water demand based on occupancy, fixture count, and peak usage patterns. Determine tank capacity, recovery time, and heating element/boiler sizing for residential, commercial, and industrial applications in Gulf climate conditions.
When to Use This Calculator
- Sizing water heaters for residential villas and apartments
- Calculating central hot water plant capacity for hotels and hospitals
- Determining storage tank volumes for peak demand coverage
- Estimating boiler sizing for district heating systems
- Verifying hot water system specifications for tender submissions
How to Use This Calculator
Enter Building Data
Input number of occupants, apartments/rooms, or specify building type (hotel, hospital, residential).
List Fixtures
Enter fixture counts (showers, basins, baths, kitchen sinks) or use typical occupancy factors.
Set Design Parameters
Specify hot water temperature (typically 60°C), cold water inlet temperature, and peak hour factor.
Select System Type
Choose instantaneous, storage, or combination system based on demand profile.
Review Results
Get recommended heater capacity (kW), storage volume (L), and recovery time.
Typical Scenarios in UAE & Gulf Projects
First-pass check for a hotel with 800 occupants. Using the tool's 40 L/person/day and 40% storage, it gives 32,000 L/day, a 12,800 L store and about 670 kW heating capacity (60°C storage, 15°C cold water, 60-minute recovery) before heater efficiency. Hotels usually need higher per-guest demand figures from the MEP consultant.
Individual heater check for a 4-person apartment: 160 L/day, a 64 L store and about 3.4 kW for a 60-minute recovery (60°C storage, 15°C cold water) before heater efficiency. The contractor then picks the nearest standard heater size and checks SEWA requirements.
Frequently Asked Questions
Take Your Calculations Further
This calculator reflects the logic built into Arkan's construction management platform.
Last Updated: January 2026
Standards Reference: ASHRAE Applications Handbook, BS 6700, CIBSE Guide G