Signs of trouble with an electric tank
- Lukewarm water, or hot water that gives out halfway through a shower.
- The safety switch trips when the tank starts heating.
- No hot water at all, even with the circuit on.
- Water seeping from the base or the side of the tank.
- A relief valve drain that drips and won't stop.
- Rusty or smelly water from the hot taps.
How a plumber will work through it
A plumber will first confirm power is reaching the unit, then test the element and the thermostat. Those are the usual failures, and both can be replaced with the tank left where it is.
Next comes the tank. Seepage from the body, or rust at the base, means the inner lining has corroded, and no part fixes that. The sacrificial anode inside is what slows that corrosion, so its condition says a lot: see anodes and other parts.
Off-peak circuits and running out
Many electric tanks are wired to an off-peak or controlled circuit that only heats at set times. If you run out late in the day, the cause may be the tariff and the tank size rather than a fault.
Your electricity bill or the label at the switchboard usually shows which circuit the unit is on. If the tank is simply too small, our sizing guide helps with the next one.
Safe checks, and where to stop
You can
- Check the hot water circuit and the safety switch at the switchboard.
- Note when the hot water runs out, and how many showers came before.
- Read the model and install date from the label.
- If it's leaking, switch the unit off at the switchboard and close the cold water valve.
Leave to a licensed plumber
- Removing the cover, and anything wired to mains power.
- Swapping the element or the thermostat.
- Thermostat settings. In Queensland, Queensland Health says adjustments should be made by a licensed electrician.
- Relief valve and anode changes.
Don't turn the tank down to save power
Storing water at 60°C or hotter keeps Legionella growth down, according to the building regulator, and lowering the storage temperature encourages it. Queensland's hot water page says water must be heated to a minimum of 60°C. To stop scalds at the shower, the answer is a tempering valve, not a lower thermostat.
Replacing an electric tank
In Queensland, the Government's hot water page sets no restriction on replacing an electric storage system. Other states may differ, so ask the plumber what's allowed where you live.
Switching to a heat pump can attract a discount. In NSW, the Energy Savings Scheme lists a figure for replacing an electric water heater with a heat pump, but calls its amounts indicative only: see NSW discounts. Eligible heat pumps under 425 L can also earn STCs.
In South Australia, a water heater replacement comes with an electronic certificate of compliance, due to you within 7 days of the work.
Whatever the job, get the plumber's licence number and look it up before work starts. Our licence guide lists each state's register.
Questions to ask
- Is it the element, the thermostat or the tank?
- Is the anode worth checking while the cover is off?
- Would a bigger tank, or a different tariff, stop us running out?
- If it's time to replace, would a heat pump suit this house, and what discounts apply?
- Will the new unit need a tempering valve here?
What we would do
If the tank is dry and it's the element or thermostat, fix it: those parts are made to be swapped. If the tank is weeping, don't spend on parts. Use the time to decide between another electric tank and a heat pump, check the discounts, and have a hot water specialist confirm the size before anything is ordered.