Calorifier Storage Capacity Calculator
Use this Calorifier Storage Capacity Calculator to estimate the required hot water storage volume and a recommended calorifier tank size based on occupancy, hot water demand and reserve capacity.
Input Parameters
Persons
L/person/day
Multiplier
%
Calculation Results
Daily Hot Water Demand
—
L/day
Peak Demand
—
L
Required Storage Capacity
—
L
Recommended Calorifier Capacity
—
L
Calculation Formulas
Daily Demand = Occupants × Hot Water RequirementPeak Demand = Daily Demand × Peak Demand FactorRequired Storage = Peak Demand × (1 + Safety Factor / 100)
The required storage is rounded up to the nearest practical calorifier tank size. Above 50,000 L it is rounded up to the nearest 5,000 L increment.
How to Use This Calculator
- Enter the number of occupants the system serves.
- Enter the expected hot water requirement per person per day.
- Set a peak demand factor to allow for busy periods.
- Add a storage safety factor for reserve capacity.
- Review the recommended calorifier size and download a PDF report.
Frequently Asked Questions
How do I calculate calorifier storage capacity?
Multiply occupants by the hot water requirement per person for daily demand, apply a peak demand factor, then add a safety margin. The result is rounded up to a practical tank size.
How much hot water storage is required per person?
A common planning figure is around 45–60 litres per person per day, varying with building type and usage. The default here is 50 L/person/day.
What is a peak demand factor?
It accounts for periods when hot water use is concentrated, such as mornings, so the calorifier is sized for peaks rather than the daily average alone.
Why add a storage safety factor?
A safety factor provides reserve capacity to cover higher-than-expected demand, heat losses and future growth.
Why is the tank size rounded up?
Calorifiers are manufactured in standard sizes, so the calculated volume is rounded up to the nearest practical capacity you can actually purchase.
Results are estimates based on the values entered and the calculation method shown. Actual system requirements may vary depending on operating conditions, demand patterns, equipment configuration and applicable project requirements.