Method
Hot-water storage volume from peak demand, recovery during peak and explicit storage margin.
Equations
Vn = max(0, Vp − Vr)
Vs = Vn · (1 + m)
Symbols and units
| Symbol | Quantity | Unit |
|---|---|---|
| Inputs | ||
| Vp | Peak-period demand | L |
| Vr | Heater recovery during the peak | L |
| m | Storage margin (0.1 = 10 %) | – |
| Results | ||
| Vn | Net storage required | L |
| Vs | Design storage | L |
Assumptions and limits
- No default storage margin.
In practice
- Only part of a stored volume is usable before the outlet temperature falls; allow for it in the margin or the demand.
Worked example
The input values are the calculator's own verification test, run through the calculator. They show the working; they are not design values.
Inputs
| Vp | Peak-period demand | 500 L |
| Vr | Heater recovery during the peak | 300 L |
| m | Storage margin (0.1 = 10 %) | 0.1 – |
Results
| Vn | Net storage required | 200 L |
| Vs | Design storage | 220 L |
A preliminary check for engineer review, not an engineering approval. The project calculation to the applicable codes, authority requirements and specification governs.