Guide
No hot water: 5 checks before you call
The short answer
On an electric hot water tank, no hot water at all usually comes down to a tripped breaker, a tripped high-limit switch (the red reset button), or a failed upper element or upper thermostat. Hot water that runs out fast points to the lower element instead. Always switch off the power at the panel before opening a cover.
The part in question
Upper elementThe whole house, or one tap?
Run the hot water in two places, the kitchen and the bathroom. If only one tap runs cold, the problem is probably in that tap or its valve, and the hot water tank is off the hook.
Cold everywhere? Head down to the basement. The next four checks go in order, from the simplest to the most technical.
The breaker
At the electrical panel, find the hot water tank's breaker. A tripped breaker often sits stuck between ON and OFF: push it firmly to OFF, then back to ON.
Some installations also have a switch or a fuse box next to the tank. Giant's manual says to check that it is ON. A blown fuse gets replaced.
If the breaker trips again, leave it off. According to the service manual of Bradford White, another manufacturer, an element shorted to ground will in most cases trip the breaker. The cause has to be found, and guesswork is a poor tool for it.
The reset button (high-limit switch)
Above the upper element, the thermostat is combined with a high-limit switch. If the water gets too hot, it cuts power to the element. It does not reset itself: you have to press its red RESET button.
Giant's procedure: switch off the power at the panel, remove the upper access cover and the insulation, press the red button, then put the insulation and the cover back before restoring power. If you are uncomfortable working next to electrical terminals, leave it to a technician.
The high-limit switch trips when the water gets too hot, and that has a cause. Giant's troubleshooting guide links overheated water to a thermostat set too high, a faulty thermostat, a thermostat that has lost contact with the tank, or a damaged element. And according to Bradford White, a reset button that has to be pressed again and again usually means a grounded element.
After a power outage
A tank that has cooled down will take a while to get hot again. Hydro-Québec says it can take up to two hours to heat a full tank.
Wait an hour, then another
That is Giant's start-up procedure. Once the power is back, wait one hour: there should be hot water at the tap. If not, check the breaker or the fuse, wait one more hour, then call a technician.
If the outage came with a storm
Giant's troubleshooting guide lists lightning and power surges among the causes of a failed element, thermostat or fuse. An outage with lightning deserves a little more suspicion than a quiet weekend outage.
A new tank, or one that was just refilled
The same one-hour wait applies. If only a little hot water comes out after that, Giant suggests checking that the hot and cold connections are not reversed. And if the power went on before the tank was full, the element may have heated dry. In that case, it gets replaced.
Lukewarm water: the lower element
The traditional electric hot water tank has two elements, each with its own thermostat. In non-simultaneous operation, only one heats at a time: the upper one first, until the top of the tank is hot, then the lower one, according to Bradford White's service manual.
That explains the two symptoms. If the upper element, its thermostat or the high-limit switch fails, the lower element never gets its turn: no hot water at all. If the lower element fails, the top of the tank still heats. The shower starts hot and ends cold.
For running out of hot water, Giant's guide is blunt: when an element is to blame, it is the lower one in 90% of cases. The other causes it lists: a thermostat set too low, sediment and scale at the bottom of the tank, a faulty dip tube, or a tank too small for the household.
When to call a professional
Call if the breaker or the red button trips again, if the water is still cold two hours after the power came back, if you smell something burning, or if the hot water runs out faster and faster. An element or a thermostat can be replaced, as long as the tank itself is still sound.
If water is also leaking around the tank, start with Hot water tank leaking from the bottom: what to do now.
M. Chauffe-Eau GL repairs electric hot water tanks, 24/7, in Montreal, Laval, the North Shore and the South Shore. Send a photo of the rating plate, and we'll get back to you with a price in under an hour.
Sources
- Residential electric water heater owner's manual, installation and operating instructions (GI-IM017En), Giant, consulted September 27, 2026
- Service Manual, Troubleshooting Guide and Instructions for Service, residential electric water heaters (238-47104-00A), Bradford White, consulted September 27, 2026
- Chauffage de l'eau 101 (24 février 2021) (in French), Hydro-Québec, Espace d'échange, consulted September 27, 2026
- Standard, Cascade & Super Cascade, Giant, consulted September 27, 2026
No hot water? Call M. Chauffe-Eau GL
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