No Hot Water in Canberra? What to Check Before You Call a Plumber

Check four things before you ring anyone, in this order: whether every hot tap is cold or just one, whether the unit still has power or gas, whether the pilot or ignition is running, and whether the isolation valve at the unit has been turned off. Most no hot water calls we take in Canberra come back to one of those four, and two of them you can sort out yourself in five minutes.

Is it the whole house or just one tap?

Run the hot tap at the kitchen sink, then the bathroom basin, then the shower. It takes a minute and it decides everything that follows.

If every outlet is cold, the fault is at the unit or at its power or gas supply. If the kitchen is hot and the shower is cold, your hot water system is fine and the problem is at that fixture, usually a worn mixer cartridge or a tap isolation valve that has been wound shut.

If the water is hot but the flow has dropped away, that is a different fault, and our guide to low water pressure causes and fixes covers it.

What should you check on an electric hot water system?

Start at the switchboard. Look for a breaker labelled HWS, hot water, or water heater. If it has tripped, reset it once. Plenty of jobs end right there.

If it trips again, stop. A breaker that will not hold usually means the element has failed or the thermostat has shorted, and pushing it back up repeatedly does the switchboard no favours.

The second thing to check is the tariff. A lot of older Canberra homes run the hot water on a controlled overnight circuit, so the tank heats in the small hours and then has to last the day. Three long showers and a load of washing will empty a 250 litre tank, and it will not reheat until the next window. If the hot water disappears late in the day and comes back by morning on its own, that is what is happening, and the answer is a bigger tank or a different tariff rather than a repair.

Also look at the unit for a cold water isolation valve, usually a small lever or gate valve on the inlet pipe. If it has been closed, the tank cannot refill.

Do not take the cover off an electric unit. The element and thermostat sit behind it with live wiring, and that panel is not a homeowner job.

What should you check on a gas hot water system?

Try another gas appliance first. Turn on a burner, or fire up the gas heater. If they are dead too, the water heater is not your problem, the gas supply to the house is. Check whether the isolation valve at the meter has been turned off, and check with your retailer that the account is still connected.

If the other appliances work, the next check is power. Most gas units made in the last fifteen years use electronic ignition rather than a standing pilot, and they need 240 volts to fire. Look for a powerpoint near the unit that has been switched off, and check the breaker.

Older units with a standing pilot have a small viewing window and a relight procedure printed on a label. Follow that label exactly as written. If the pilot does not hold after two attempts, stop and call a licensed gas fitter. Do not remove panels and do not adjust the gas valve.

If you can smell gas at any point, do not attempt to relight anything. Turn the gas off at the meter if you can reach it safely, open the windows, get everyone outside, and ring the Evoenergy gas emergency line on 13 19 09. Evoenergy publishes its gas safety advice for the ACT network.

Why does my pilot light keep going out?

A pilot that lights and then drops out an hour or a day later has one of four causes, and all four are a licensed gas fitter's work.

• A worn thermocouple. This is the small sensor sitting in the pilot flame that tells the gas valve the flame is there. As it ages it stops generating enough signal and the valve shuts the gas off, which is what it is designed to do. Most common cause by a distance.
• A blocked pilot injector. Dust and spider web narrow the orifice and starve the flame. Cleaning it means opening the burner compartment, which is gas work.
• Draught. Units mounted on an exposed wall get blown out, and in Canberra it is usually the westerly side of the house that suffers. A flue cowl or a wind deflector sorts it.
• Gas pressure. If the pilot only drops out when the ducted heater kicks in, the supply pressure is sagging under load. That needs a manometer test on the line, not a new thermocouple.

If the unit is past ten years old and you are relighting it weekly, you are spending money on a tank that is close to the end anyway. Our licensed gas fitting work covers the diagnosis either way.

What should you check on a heat pump hot water system?

Check the breaker and the isolating switch first, same as an electric unit. Then read the controller. Nearly every heat pump displays a fault code when it stops, and that code narrows the diagnosis straight away. Write it down before you call. It can be the difference between one visit and two.

Cold weather is worth understanding rather than worrying about. A heat pump pulls warmth out of the outside air, so on a Canberra winter morning it runs defrost cycles and recovers more slowly than in January. The Bureau of Meteorology puts the mean July minimum at Canberra Airport at 0.1 degrees. Slow recovery in July is normal. No recovery at all is a fault.

Last check is airflow. Leaves packed against the fan, a fence built too close, or a cover someone put over the unit will all choke it.

Why is the water lukewarm instead of properly hot?

Lukewarm everywhere usually means the tempering valve is failing. That is the valve limiting water to the bathroom to 50 degrees, and when the cartridge inside it wears out it lets too much cold through. Small part, quick job, and the most common cause of a warm shower that used to be a hot one.

The other likely cause on an electric tank is one dead element. Larger units have two, and when the top one fails you get a partly heated tank that runs cool almost immediately. Sediment in the bottom of an old tank does the same thing more gradually.

What does each symptom usually mean?

When should you stop checking and call a plumber?

There is a point where more poking about costs you money rather than saving it. Ring someone if any of these apply:

• Water is pooling under the unit, or there is rust staining around the base. The cylinder has gone and no repair brings it back.
• The relief valve is running constantly rather than dribbling occasionally, which it is meant to do.
• The breaker trips a second time after you reset it.
• The pilot will not hold after two attempts.
• You can smell gas, in which case ring Evoenergy on 13 19 09 before you ring us.
• There is no hot water and no obvious reason for it, and the unit is over ten years old.

The checks above are not wasted effort even when they do not fix anything. Telling us the breaker held, the cooktop works and the pilot is lit rules out most of the diagnosis before we arrive, and it often means we turn up with the right part on the van.

Is it worth repairing the unit or replacing it?

Age decides most of it. Gas and electric storage tanks last roughly 8 to 12 years, heat pumps 10 to 15, and solar panels 15 to 20 with a shorter life on the tank and booster underneath.

Under about eight years with one failed part, repair it. A thermocouple, a tempering valve, an element or a thermostat are all straightforward and none of them cost anything like a new system. Past ten years with a leaking cylinder, or a second failure inside twelve months, replacement is the cheaper call even though the invoice is bigger. What a new system costs in the ACT is set out in our guide to hot water system cost in Canberra, and if you are weighing up a change of type, we compare gas, electric, solar and heat pump systems side by side.

We do hot water repairs and replacements across the ACT, including same-day work in Tuggeranong. If your unit died on the coldest morning of the year, the rest of the house is worth a look too, which is what our Canberra winter plumbing guide is for.