HPWHs can work any time there is a need for hot water heating and a cooling load or opportunity. Performance varies with the situation. An economic comparative analysis must be benchmarked against some alternative arrangement. Energy performance is fairly straightforward. This means they produce about twice as much hot water per kWh as electric resistance water heaters.
Maintenance costs are greater than simple resistance water heating.
The maintenance requirements and cost are more similar to that of conventional air conditioning equipment of similar tonnage. Note that if the application was a retrofit rather than new construction, this benefit wouldn't apply. In recent years the market has slowed for stand-alone commercial heat pump water heaters. Competition with gas water heaters is strong because of recent good gas prices. Also electric rates have not risen as fast as projected in many areas.