Many homeowners in Ontario find their hydro bill stays high even after switching to Ultra-Low Overnight (ULO) pricing. One key reason is that electric water heaters run automatically and often operate during higher-cost hours when household activity is higher. As a result, a significant portion of electricity use remains outside the lowest-rate overnight period, reducing the expected savings under ULO.

In a typical household, hot water is used most in the morning and evening. Each use triggers reheating, and stored heat is gradually lost throughout the day, causing the water heater to cycle during higher-cost periods. This leads to higher electricity costs under ULO.

Under ULO pricing, the cost of electricity depends heavily on when it is used. Because water heaters operate automatically, they often run during higher-cost periods unless their operation is managed. As a result, even without increasing total electricity usage much, they can keep your hydro bill significantly higher than expected.