This is the question we get asked standing next to a wet hot water unit more than any other, and the honest answer depends on four things: how old the unit is, what part of it has failed, whether parts still exist for it, and whether the tank itself is leaking. Get those four straight and the decision mostly makes itself. Here is how we work through it on a Gold Coast driveway.
Repair or replace: the usual call by fault
| What has gone wrong | Usual call | What it costs |
|---|---|---|
| Water weeping from the tank body or from under the outer casing | Replace | Installed ranges in the table below |
| Pressure and temperature relief valve dripping or running | Repair | Quoted after diagnosis |
| Electric element or thermostat failed on a unit that is otherwise sound | Repair | Quoted after diagnosis |
| Gas storage pilot will not stay lit, thermocouple or gas valve fault | Repair, by a licensed gas fitter | Quoted after diagnosis |
| Continuous flow unit showing an error code | Repair if the part is still made | Quoted after diagnosis |
| Old unit on its second or third fault in a short space of time | Replace | Installed ranges in the table below |
| Unit past its warranty with parts no longer available | Replace | Installed ranges in the table below |
Replacement cost, supplied and installed
| System type | Supply and install |
|---|---|
| Electric storage, like-for-like | $1,300 to $2,400 |
| Gas storage, like-for-like | $1,800 to $3,200 |
| Gas continuous flow | $1,900 to $3,500 |
| Heat pump, after STC rebates | $2,500 to $4,500 |
Repairs do not have a published figure because there is no honest way to price one before someone has looked at the unit. We diagnose first, then give you a fixed price for the repair, and at the same time tell you what a replacement would cost so you can weigh the two side by side.
Why is a leaking tank always a replacement?
Because the tank is the one part that cannot be fixed. A storage cylinder is a steel vessel with a glass or enamel lining and a sacrificial anode inside it that corrodes so the steel does not. Once water is coming through the tank wall, the lining has failed and the steel has rusted through. There is no patch, weld or sealant that a licensed plumber will put on a pressurised hot water cylinder, and no manufacturer would stand behind one. First, be sure it is actually the tank. Water pooling under a unit often turns out to be the relief valve discharging down its drain line, a weeping fitting on top, or a cold water connection, and all of those are repairs. We check the valves and connections before condemning anything. But once we confirm the water is coming from the cylinder itself, the conversation moves to which replacement suits you, not whether to repair.
Which repairs are genuinely worth doing?
Valves and elements, on a unit that has life left in it. A relief valve that drips constantly is one of the most common hot water faults on the Gold Coast and it is a straightforward part swap. An electric element or thermostat that has failed on an otherwise sound tank is also a sensible repair, and the tank keeps going afterwards. On gas storage units, a pilot that will not stay lit is usually a thermocouple, and on continuous flow units many error codes point to a single component such as a flame sensor, a fan or an ignition module. Those faults do not tell you anything about the condition of the rest of the unit, so on a younger system a repair is the right money. One point on licensing: any repair to the gas side of a gas hot water unit is gas work and must be done by someone holding a Queensland gas work licence, which is separate from the plumbing licence. Ask for it.
How does the age of the unit change the answer?
The older the system, the weaker the case for repair. A repair fixes the part that failed and nothing else. If the tank is well into its life, the element you replace today may be followed by a relief valve next winter and a leaking tank the summer after, and you will have paid for three visits on the way to the replacement you could have bought at the first one. The rating plate on the side of the unit shows the date of manufacture, so you do not have to guess. Our rule of thumb, set out on our should I repair or replace my hot water system page, is simple: under 8 years old, usually repair; over 12, usually replace; in between, it depends on what has failed. A leaking tank is a replacement at any age and a valve on a young unit is a repair at any age. The years are a guide rather than a law, because tanks on the coast age faster than tanks in the hinterland and a well-maintained unit with its anode changed outlasts a neglected one, so on site we tell you plainly whether we think the unit has enough left in it to justify the repair. If we would not spend the money on our own house, we say so.
Do parts still exist for my unit?
This is the question that decides a surprising number of jobs. Elements, thermostats and relief valves are common across brands and are usually on the van. Gas valves, control boards and continuous flow components are model-specific, and for older or discontinued units the part may no longer be made. Chasing a part for weeks while the household has no hot water is rarely the right call, and the cost of an obsolete part, when one can be found, sometimes sits close to a replacement unit. We check availability as part of the diagnosis and tell you before you commit.
What about the running cost side?
If the unit is old enough that replacement is on the table, it is worth asking what you would replace it with rather than defaulting to the same thing. An electric storage tank on a full-rate tariff is the cheapest unit to buy and the dearest to run. A heat pump costs more up front, $2,500 to $4,500 after STC rebates, and is the cheapest to run in the Gold Coast climate, especially with rooftop solar. Gas continuous flow at $1,900 to $3,500 suits big households that keep running out of hot water. A repair on an old electric tank can be the right short-term call and still the wrong long-term one, and we would rather you made that choice knowing both numbers.
What paperwork applies?
In Queensland a like-for-like hot water replacement is notifiable work, so the plumber lodges a Form 4 with the QBCC after the job. Gas units also need a gas compliance certificate from the licensed gas fitter. Valve, element and thermostat repairs do not carry the same paperwork, but you should still receive an invoice showing the licence number and the parts fitted. Keep it, because it is the record that supports any warranty claim later.
How we make the call on site
Look at the unit, find the fault, check the rating plate, check whether the part is available, and check whether the tank is dry. Then we give you two prices: the fixed repair and the installed replacement. Most of the time one of them is obviously the better spend, and we tell you which one we would pick for our own place. Owner operator, 13 plus years on the tools, QBCC plumbing licence 15243081.
Not sure whether your unit is worth saving? Call Hills Plumbing & Gas on 0472 657 042 or book through our Hot Water Repairs service page. We will diagnose it, quote the repair, and tell you straight if replacement is the better spend.