No Hot Water? What to Check First

The first thing to check with no hot water is whether anything else in the house has lost the same supply. Run a cold tap: if nothing comes out of either tap, the problem is the water supply to the property, not the hot water system.

If the cold runs and the hot doesn't, go through these in order. Has the household used a lot of hot water in the last few hours, with guests, back-to-back showers or a full washing load? A storage tank can simply be empty and reheating. Is the power on to the rest of the house, and are other gas appliances, like the cooktop, still lighting? Is there a display or controller on or near the unit, and is it showing an error code? Write the code down.

Three findings end the checklist straight away: water escaping from the tank or its fittings, any smell of gas, or a switch that trips again after one reset. Each of those is a call, not a check.

On an electric storage tank, the first owner check is the switchboard. Look for a circuit breaker or safety switch that has dropped to the off position, often labelled hot water or HWS. Some tanks also have an isolating switch on the wall nearby; check that it is on.

If a switch has tripped, you can reset it once. If it trips again, leave it off. Queensland's Electrical Safety Office says a safety switch that trips during normal use may point to a fault, and that if it trips again after a reset you should get advice from an electrician. The same guidance is plain that you should always have a licensed electrician do your electrical work. So the owner's part ends at the switchboard.

If nothing has tripped and the tank is on an off-peak tariff, the next question is timing, covered below.

An electric tank on an economy tariff only heats when the network supplies that circuit, so a tank that was emptied in the evening may stay cold until its next window. Energex, the network for south-east Queensland, describes two economy tariffs. Tariff 31, which retailers may call Super Economy, Night Rate or Controlled Load 1, supplies 8 or more hours a day, around 10pm to 7am. Tariff 33, also sold as Economy or Controlled Load 2, supplies 16 or more hours, usually outside 4pm to 9pm.

Energex also says those times can change with the needs of its network. It has described moving economy scheduling towards soaking up rooftop solar, with supply typically interrupted during the morning peak and resumed in the middle of the day, and notes that appliance timers may need their settings updated.

So a cold tap after a heavy evening, with no tripped switch, may not be a fault at all. If the tank is still cold after a full window, it is.

With a gas system, check the gas before the heater. If you're on mains gas, does the cooktop light? If you're on bottled LPG, has the cylinder in use run out? An empty cylinder gives exactly the symptom of a broken heater, and your gas supplier can sort out a replacement.

Next, power. A gas unit with a display or electronic controls needs electricity as well as gas. If the unit plugs into an outdoor power point, check the power point is switched on and that nothing has tripped at the switchboard. Then look at the display or the controller inside the house and note any error code.

If the unit has gone out and the manufacturer gives lighting instructions on the unit or in the owner's manual, those are the only steps an owner should follow. Beyond that is gas work. In Queensland only a licensed gasfitter can carry out gas work, which includes installing, altering, repairing, servicing or testing the gas system and its connections.

A smell of gas near a hot water system changes the job from troubleshooting to safety. The Queensland Government's gas safety guidance is short and worth following exactly: don't light anything and don't switch electrical devices on or off, turn off the gas appliance, and open doors and windows. If you can still smell gas, turn off the gas supply and contact your gas supplier or a gasfitter. If you can still smell it after the supply is off, call 000.

Don't try to relight a burner while there is any smell, and don't go looking for the leak yourself beyond what that guidance describes. Once the area is safe, the heater needs a licensed gasfitter before it runs again.

A heat pump that has stopped making hot water is usually checked the same way as an electric tank, with two extra places to look. First, power: check the switchboard for a tripped circuit and any isolating switch near the unit is on. Second, the timer: if your heat pump has one, check it is set to run when you expect, and if the unit is wired to an economy tariff it can only run when the network supplies that circuit. Energex has said timers on economy-tariff appliances may need updating when its schedules change, so a timer set years ago may now miss the supply window.

Third, the display. Note any error code and look it up in your own owner's manual, because codes differ by brand and model.

Don't open the unit. Nothing inside a heat pump's casing is owner work.

If your solar hot water system has an electric or gas booster, the booster is the first thing to check when the water goes cold after a run of cloudy days. A solar system with its booster switched off, tripped, or out of gas will only be as hot as the sun made it, which after several overcast days can be lukewarm or cold.

For an electric booster, check the switchboard and any booster switch for the solar system. For a gas booster, check the gas supply the same way as for a gas heater. If there is a controller with a display, note what it shows.

If the booster is on and working and the water is still cold, the fault may be in the collectors, the circulation pump or the controller. Those are a plumber's job, and on the roof they are also a safety problem, so leave them for the service visit.

If the kitchen tap runs hot but a shower or one bathroom doesn't, the hot water system itself is heating. The fault is somewhere between the tank and that outlet: the valve that controls the temperature of water delivered to that part of the house, the shower mixer, or the pipework to it.

That narrows the job, and it is useful to tell the plumber when you call. Say which outlets are hot, which are cold or lukewarm, and whether the change was sudden. Don't adjust or dismantle valves or mixers to find out more: in Queensland most plumbing work has to be done by a licensed plumber.

No hot water on its own is uncomfortable rather than dangerous. A cold shower is unpleasant, but if nothing is leaking, there is no gas smell and nothing is tripping, it can usually wait for a scheduled visit, and urgent or out-of-hours work generally costs more.

It becomes urgent when one of three things is happening. Water is escaping from the tank or its fittings, which can damage walls, floors and cupboards quickly. You can smell gas. Or the electrical supply to the system keeps tripping. In any of those, isolate what you safely can, follow the gas safety steps above if gas is involved, and call.

For tenants, the answer is different, because Queensland tenancy law treats a hot water failure as an emergency repair. The next section covers who to contact.

If you rent in Queensland, a failure or breakdown of the hot water service is an emergency repair under tenancy law, according to the Residential Tenancies Authority. The emergency repair rules do not apply to rooming accommodation. The tenancy agreement names who to contact first for emergency repairs, either the property manager or owner, or a nominated repairer.

The RTA says the tenant should make every effort to contact that person as soon as they know about the problem. A phone call is enough, though a short follow-up text or email confirming what was said is good practice.

If the tenant can't reach the emergency contact within a reasonable time, either the tenant or the property manager can arrange the repair, up to a maximum of four weeks' rent. Keep every receipt, and read the RTA page on reimbursement before paying for anything yourself.

A plumber can tell a lot from a short, specific description, and it can be the difference between a visit that fixes the problem and one that has to come back with a part. Before you call, gather:

The system type: electric tank, gas tank, continuous flow, heat pump or solar. The brand and model from the data plate on the side of the unit, if you can read it without moving anything, and roughly how old the system is. A photo of the data plate and of the whole unit. Any error code on the display. What you've already checked: which switch tripped, whether it tripped again, whether the gas is on. Which taps are cold and which are not. Your suburb.

If the checks above haven't found the cause, the next step is a repair visit. If the system is old and this is not its first failure, it is also worth reading about repairing versus replacing before you decide.