No hot water on a Canberra morning in July is not a minor inconvenience. With frosts most nights and the incoming mains water close to freezing, a household with a baby, a shift worker or an elderly resident needs it fixed the same day, and the plumber needs to give a straight answer on whether the unit can be repaired or has reached the end. This page covers the systems found in Canberra homes, why they fail in winter, what frost does to relief valves, the ACT gas phase-out and what it means for your next unit, and how the repair-or-replace decision is made.
Hot water systems in Canberra homes
Older suburbs run on electric storage tanks, often outside against a wall or in the laundry, and many are on their second or third replacement in the 1970s to 90s homes of Kambah, Wanniassa, Calwell, Kaleen and Florey. Gas storage and gas continuous flow units are common in Woden Valley, Weston Creek and the inner suburbs where the gas network was laid early, and in the 1990s and 2000s homes of Gungahlin. Solar hot water with an electric or gas booster sits on many 2000s roofs in Coombs, Harrison and the Duffy and Chapman bushfire rebuilds. Heat pumps are the fastest growing type, both in new estates and as replacements. Each type fails in its own way, and the repair starts with knowing which one you have and roughly how old it is.
Why hot water fails in a Canberra winter
Winter is the hard season. The mains water arriving at the unit is colder, so an electric element or gas burner runs longer and harder to reach temperature, showers get longer, and a household uses more hot water for washing and heating. An element, thermostat, thermocouple or burner that was coping in autumn gives out under that load. Storage tanks fail in winter in the same way, with the added problem that a corroded tank finally weeps at the base after years of expansion and contraction. Because most of Canberra’s tanks are outside, the plumber is often working on a unit that has spent the night below zero, and may be thawing lines before anything can be diagnosed.
Frost and the relief valve
Every storage tank has a temperature and pressure relief valve with a drain line that runs to the ground outside. It is meant to drip a little as the tank heats. On a frosty night that drain line, and sometimes the valve itself, freezes. A frozen relief line means the valve cannot release pressure, which is a safety issue, and repeated freezing damages the valve seat so it either sticks or runs constantly once it thaws. Never plug or cap the relief line to stop the dripping. If it is running in a steady stream, the valve has failed or the mains pressure is too high, and the fix is a new valve, a pressure limiting valve, or both. Lagging the relief line and the exposed hot and cold pipes at the unit before June is the single cheapest thing a Canberra homeowner can do for a hot water system. The frozen pipes winter guide covers it.
Repair or replace: the honest answer
A tank in sound condition with a failed element, thermostat, relief valve or thermocouple is worth repairing, and the plumber will say so. A tank that is leaking from the body, rusted through at the base or well past the life its maker intended is not, because a repair buys months and the tank will let go in the next cold snap anyway, usually at night. You are told which it is on site, with a price for the repair and a price for the replacement, before anything is done. Where a replacement is the answer, the choice of unit is talked through properly rather than defaulting to whatever is on the van.
Heat pumps and the ACT gas phase-out
The ACT is phasing out fossil gas. New connections to the gas network have been prohibited since 8 December 2023, and the ACT Government aims to be off gas by 2045. If your home is already connected, a gas hot water unit can still be repaired or replaced like for like by a licensed gasfitter. If it is not, gas is not an option, and for many households replacing a gas unit the question is whether to install another one that will eventually have to be replaced by something electric anyway.
Heat pump hot water systems are the usual answer. Modern cold-climate units operate well below zero, although they run longer on frosty mornings and some use a booster element on the coldest nights, and they use far less electricity than a standard electric storage tank. Placement matters here: the unit needs clear airflow, should not be boxed in, and the relief line should be protected from frost. The plumber will tell you whether your site suits one, what the electrical side involves, and whether a plain electric storage tank or an electric continuous flow unit makes more sense for your block. Rebates and schemes change, so ask what is current rather than relying on a web page.
Mains pressure and pressure limiting valves
Canberra’s mains pressure varies with the hills. Low-lying homes near Lake Tuggeranong, in Phillip or along the flat of Belconnen can see pressure high enough to shorten the life of every valve in the house, and the mains-pressure hot water systems standard in 1990s and 2000s Gungahlin homes rely on a pressure limiting valve that is now failing across Harrison, Ngunnawal, Franklin and Casey. A failed limiting valve shows up as a relief valve that runs constantly, a hot water tank that hammers, and a tempering valve that cannot hold a stable temperature. Replacing it is routine and is checked on every hot water call.
Licensing, compliance and what to expect
Hot water installation and repair is plumbing work, and in the ACT it must be done by a tradesperson licensed by Access Canberra under the Construction Occupations (Licensing) Act 2004. Any gas unit requires a licensed gasfitter, who issues a compliance certificate for the work. In Queanbeyan, Jerrabomberra and Googong the licence comes from NSW Fair Trading. A new installation has to meet current requirements for tempering valves, relief drains, pressure and electrical isolation, which is why a like-for-like swap on a 1980s install often involves more than the tank. You can ask for the licence number, and the price for the work is agreed before it starts. For a failure at night or on a weekend, the 24 hour plumber page explains how after-hours calls work, and the gas plumber page covers gas appliance work more broadly.
What is included
- Diagnosis of no hot water, not enough hot water, leaks and noise on electric, gas, solar and heat pump systems
- Replacement of temperature and pressure relief valves, thermostats, elements, thermocouples and tempering valves
- Supply and installation of replacement electric storage, continuous flow and heat pump units
- Advice on heat pump options given the ACT gas phase-out and the ban on new gas connections
- Pressure limiting valve and isolation valve replacement on mains-pressure systems
- Frost protection for relief lines and exposed pipework on outdoor units
- Licensed gasfitting and a compliance certificate where gas work is involved
Signs you should call now
- No hot water, or hot water that runs out far sooner than it used to
- Water dripping or running constantly from the relief valve or the overflow pipe
- Rusty or discoloured hot water, or a tank that is weeping at the base
- A gas unit whose pilot keeps going out, or a continuous flow unit showing an error code
- Banging, rumbling or kettling noises from a storage tank
- The circuit breaker for the hot water tripping repeatedly
- Water temperature swinging between scalding and cold at the taps
Never cap a leaking relief valve
The temperature and pressure relief valve on a storage tank is supposed to drip a little as the water heats, but a constant stream or a frozen, blocked relief line is a fault. Never cap or plug the relief line to stop a drip; it is the safety device that stops a tank over-pressurising. Turn the cold water isolation tap off at the tank and call.
Frequently asked questions
Why do hot water systems fail in a Canberra winter?
Winter is the hardest season for a hot water system. Incoming mains water is colder, so the unit works harder and longer to reach temperature, showers are longer, and an ageing element, thermostat or burner that coped in March gives up in July. Frost also freezes the relief drain line on outdoor units and can damage the valve. Tanks on their second or third replacement in Tuggeranong and Belconnen homes are the usual casualties.
Can I still install a gas hot water system in the ACT?
If your home already has a gas connection, a gas hot water unit can still be repaired or replaced like for like by a licensed gasfitter. New connections to the gas network in the ACT have been prohibited since 8 December 2023, so a home without gas cannot add it, and the ACT Government aims to be off gas by 2045. For most replacements the plumber will walk you through heat pump and electric options alongside gas.
Is a heat pump worth it in Canberra's cold?
Modern heat pump units are designed for cold climates and operate well below freezing, although they run longer on frosty mornings and some models use a booster element when it is very cold. They use far less electricity than a standard electric storage tank. Placement matters in Canberra: the unit needs airflow and should not sit where the relief line freezes. The plumber will tell you honestly whether your site suits one.
Should I repair or replace my hot water system?
It depends on the age and condition of the tank. A thermostat, element, relief valve or thermocouple on a tank in good condition is worth repairing. A tank that is leaking from the body, badly corroded or well past its expected life is not, because the repair buys months rather than years. You will be told which it is on site and given a price for each option before deciding.
Why is water running from the pipe on the side of my tank?
That is the relief valve drain. A small drip while the tank heats is normal. A constant stream means the valve has failed or the mains pressure is too high, which is common in low-lying Canberra suburbs and in Gungahlin homes where the pressure limiting valve has failed. In winter the drain line can freeze solid, which stops the valve working. Both are straightforward repairs but neither should be ignored.
How do I protect my hot water system from frost?
Lag the exposed hot and cold pipes and the relief drain line on an outdoor unit with pipe insulation, make sure the relief line drains freely and does not have a low point where water sits and freezes, and keep the area around the unit clear. On a heat pump, do not enclose the unit. For a house left empty over winter, ask about setting the unit to a holiday mode rather than switching it off completely.
Do I need a licensed plumber to replace a hot water unit?
Yes. In the ACT, hot water installation is plumbing work that must be done by a tradesperson licensed by Access Canberra, and any gas unit requires a licensed gasfitter who issues a compliance certificate. The installation has to meet current standards for tempering valves, relief drains and pressure, which older installs often do not. In Queanbeyan the licence is issued by NSW Fair Trading. Ask for the licence number.
