In addition, this water heater exchanger uses propane, and the main burner ... have to wait for 10-20 seconds before getting hot water. Some gas tankless heaters may come with a built-in ...

The Department of Energy estimated the costs saved over the long run by the new rules would be about $112 over 20 years.

The new standards, published the day after Christmas, are meant to reduce costs and various emissions, and lead to a “significant conservation of energy,” the Department of Energy’s Office of Energy ...