05/20/2026
Most commercial DHW sizing errors start with the same miss:
Peak day gets modeled. Peak hour gets ignored.
📆 Peak day tells you total demand.
⌚ Peak hour tells you whether the system can keep up when demand stacks up fast.
A 200-room hotel with a 6 to 9 AM shower window does not care about the 24-hour total. It cares about recovery, storage, and flow when the morning load hits.
The fix is not always bigger equipment.
It is better load math:
- Concentrated draws
- Simultaneity factors
- Recovery against the actual demand curve
- Storage strategy that matches the peak window
That is where commercial water heating specs either hold up or force changes after startup.
How does your team check peak-hour assumptions on DHW projects?