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Hot water, off-peak and the fine print

Do you have a controlled load? And should you still?

What a controlled load actually is

A second, separate circuit that feeds one appliance — nearly always the hot water cylinder — which your network switches on only during set hours.

Two circuits leaving your meter Your meter feeds two separate circuits. One runs everything in the house and is available all the time. The other runs only the hot water cylinder, and the network decides when it is switched on. Your meter Lights, power, everything else On whenever you want it Network switch Hot water cylinder Only heats in the hours the network allows
Cheaper power per unit, in exchange for the network choosing the hours.

In south-east Queensland it shows up as Tariff 31 (about eight hours overnight) or Tariff 33 (about eighteen hours a day). Occasionally a pool pump or underfloor heating sits on it too. The cylinder itself is completely normal — it is only the circuit feeding it that is different.

Three ways to check, easiest first

  1. 1

    Look at your bill

    You are looking for two usage lines rather than one. The second is usually called Controlled load, Off-peak, Tariff 31 or Tariff 33, and it will have a noticeably lower rate. If it is there, you have one.

  2. 2

    Notice when the hot water heats

    No bill handy? If you run the hot water dry in the evening and it is only back to normal the next morning — never within an hour or two — that is a controlled load waiting for its window.

  3. 3

    Open the switchboard

    Look for a breaker labelled hot water, off-peak or controlled load, separate from the general power circuits. Just look; there is no need to touch anything.

Why it suddenly matters

A controlled load heats your water at 1am. Solar, batteries and the newer plans all want it heated at midday. Same cylinder, opposite instructions.

A day, and when the power is cheap Solar generation peaks in the middle of the day, when some plans give power away free between 11am and 2pm. The evening peak from 4pm to 9pm is the most expensive time. A controlled load heats overnight, missing the free middle of the day entirely. your solar FREE 11–2 PEAK 4–9 12am 6am 12pm 6pm 12am Your controlled load heats here — while the sun is down and nothing is free
The free window and your own solar both land in the middle of the day. A controlled load cannot reach either of them.

That is why some retailers will not sell you a solar or free-window plan while a controlled load is on the meter. The plan assumes you can move your biggest flexible load into the middle of the day. With a controlled load, you cannot — the network holds the switch.

The catch nobody mentions

Take the controlled load off and do nothing else, and your cylinder heats whenever it feels like it — including through the most expensive hours of the day.

Three ways the same hot water can be billed Illustrative yearly cost of heating hot water. On a controlled load, roughly seven hundred dollars. Heated in a free midday window, close to nothing. Left uncontrolled and heating during the evening peak, substantially more than the controlled load. ~$700 Controlled load what you pay now ~$0 Heated at midday free window or your solar ~$1,800 Removed, uncontrolled heating in the evening peak
Illustrative only, assuming a cylinder using about 10 kWh a day. Your cylinder, your household and your tariff will all move these numbers — but the shape holds.

Removing the controlled load is only worth it if something then decides when the cylinder heats. That can be a simple timer, or a controller that heats on your own surplus solar and in the free window. Without one, you have swapped a cheap fixed window for an expensive random one.

How it gets removed

  1. Your retailer starts it. You cannot ask the network directly — the request for a tariff and metering change goes through whoever sells you power.
  2. An electrician rewires the cylinder from the controlled-load circuit onto the normal power circuit at the switchboard. This part needs someone on site. Typically a few hundred dollars.
  3. The meter is reconfigured and the controlled-load record retired. On a smart meter this is often done remotely, but only after the wiring has changed.
  4. Add the control — a timer or a controller — ideally at the same visit, while the electrician is already at the board.

Allow a couple of weeks for the paperwork. Check first whether anything else shares that circuit: a pool pump or underfloor heating sometimes does, and it will move too.

What to ask, word for word

Ring your retailer and ask these. Any of them will get you a straight answer.

  • “Does my meter have a controlled load on it, and which tariff is it — 31 or 33?”
  • “What is on that circuit besides the hot water?”
  • “What would it take to move my hot water onto the general tariff, and what would you charge?”
  • “If I remove it, can I put it back later?”
  • “Which of your plans am I not eligible for while the controlled load is there?”

Worth knowing before you call: removing a controlled load is not always reversible on the same terms, so the fourth question matters more than it sounds.

Not sure it is worth changing?

It depends on your cylinder, when your household uses hot water, and what your solar does at midday. We can work it out against your actual usage rather than a rule of thumb — and if the answer is leave it alone, we will say so.

Talk to us about your setup