A family of four is selecting a storage water heater. Which comparison is most useful for checking whether it can meet their busiest hour of hot-water use?
- ACompare the heater height with the room height, without considering demand
- BChoose only by the tank diameter
- Compare the first-hour rating with the household’s estimated peak-hour hot-water demand
- DUse the number of bathrooms alone, without considering how they are used
Where to look it up
https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/26465.pdf
Why C is correct
Estimate how much hot water the household needs during its busiest hour and compare that demand with the storage heater’s first-hour rating. That rating reflects both stored water and the heater’s ability to heat incoming water. Bathroom count can inform usage estimates, but does not describe the timing or amount of use by itself. Physical dimensions matter for installation fit and are not a substitute for this performance comparison. Source: https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/26465.pdf