Who to hire for a hot water system that needs replacing

Short answer

A licensed plumber, and a gasfitter as well if it is a gas unit — in practice the same person, holding both. If you are changing fuel type rather than swapping like for like, get the quote to spell out the new wiring, gas sizing or drainage, because that is where a cheap-looking quote turns out to be incomplete.

Soon, not tonightIt will not usually get cheaper by waiting, and it is rarely worth an after-hours rate.

When it is someone else

Calling the wrong trade costs an attendance fee to be told so. These are the cases where this problem belongs to someone other than a Plumber.

  • an electrician

    you are moving to a heat pump or adding a boost circuit. Heat pumps draw differently from an old resistive element and may need their own circuit.

  • a solar hot water installer

    you are putting collectors on the roof. That is roof work plus plumbing, and rebate eligibility usually depends on the installer's accreditation rather than the plumber's licence.

What to do before anyone arrives

  1. Photograph the old unit's data plate — brand, model, capacity, and whether it is gas, electric, heat pump or solar. A quote given against a photo is a quote, not a guess.
  2. Measure the space, including the doorway it has to come through. Heat pumps in particular are physically bigger than the electric tanks they replace.
  3. Check what rebates exist where you live before you commit, and whether they require a particular product list or an accredited installer. Some are claimed by the installer and some by you, and the sequence matters.
  4. Decide how many people are actually showering in the morning. Undersizing to save money on the unit is the single most common regret with hot water.

What to ask when you book

  • Is the compliance certificate included, and will I get a copy?
  • Does the quote include the tempering valve, expansion control, safe tray, drain line and disposal of the old unit?
  • What is the warranty on the cylinder, on the parts, and on your labour — they are three different periods.
  • If you find the existing electrical or gas supply is not adequate, what happens to the price and do you tell me before you proceed?

What changes the price

No dollar figures here: this directory holds no price data and an invented range is worse than none. What follows is what makes one of these jobs cost more than the same job next door, which is the part you can actually use when comparing quotes.

  • Like-for-like swap versus a change of fuel type or location.
  • Access: ground level against an external wall is the cheap case; a roof, an internal cupboard or a second storey is not.
  • Bringing the installation up to current requirements the old one predates.
  • Whether the electrical supply or gas pipe sizing has to change to suit the new unit.

Is this licensed work?

Installing, replacing or relocating a water heater is licensed plumbing work, with a gasfitting licence required for gas units and an electrical licence for the circuit on an electric one. Most states require a compliance certificate for the plumbing work; keep it, because it is what a buyer's conveyancer asks for.

There is no national register. Search the licence number with the regulator for the state the work is happening in.

Licensing thresholds and certificate requirements differ by state and change with amending regulation, so this page describes the mechanism rather than quoting a figure. The regulator’s own page is the current answer.

Common questions

Who should I hire for a hot water system that needs replacing
A licensed plumber, and a gasfitter as well if it is a gas unit — in practice the same person, holding both. If you are changing fuel type rather than swapping like for like, get the quote to spell out the new wiring, gas sizing or drainage, because that is where a cheap-looking quote turns out to be incomplete.
Do I have to replace it with the same type?
No, and it is the best moment to change, because the disruption is already paid for. What you should not do is assume the swap is free of consequences — a different type can need a different circuit, a different gas pipe size, a different location and a different drain.
What is a tempering valve and do I need one?
It is a valve that mixes hot and cold so the water reaching bathroom outlets cannot exceed the maximum set by plumbing regulation, which exists because children and older people are scalded by water that feels fine to an adult hand. On a new or replaced installation it is required, and it is a routine part of the job rather than an upsell.

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Who to hire for

General information about who does what, not advice about your specific job. Licensing, consumer law and council rules differ by state and change; the regulator for your state is the current source. More guides to hiring a tradesperson.