In a city that can experience four seasons in a single day, having a reliable hot water system isn’t just a luxury—it’s a necessity. If you’ve ever been the last one in the shower only to find the water turning icy, or if you’re tired of paying to heat a massive tank of water you aren’t even using, an instantaneous system might be the perfect solution for your Melbourne home.

At King and Sons Plumbing, we specialise in Instantaneous Hot Water Installation Melbourne. This “tankless” technology is rapidly becoming the gold standard for efficiency and space-saving. In this guide, we’ll answer your most common questions to help you determine if making the switch is right for you.

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What is an Instantaneous Hot Water System?

Unlike traditional storage units that keep 100+ litres of water hot all day and night, an instantaneous hot water system (also known as a continuous flow or tankless system) only heats water when you turn on a tap.

How does instantaneous hot water work?

The process is ingenious in its simplicity:

1. Detection: When you open a hot water tap, a sensor inside the unit detects the water flow.

2. Ignition: This sensor triggers either a gas burner or an electric heating element.

3. The Heat Exchanger: The cold water travels through a coiled pipe called a heat exchanger, which is instantly heated by the burner or element.

4. Delivery: The water reaches the desired temperature within seconds and flows directly to your shower or sink.

Because there is no tank, you never “run out” of hot water. As long as you have a gas or electricity supply, the hot water will keep flowing.

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Gas vs. Electric: Which is Right for You?

One of the first decisions you’ll need to make is whether to go with a gas-powered or electric-powered unit.

Can you get electric instantaneous hot water systems?

Yes, you certainly can. Electric instantaneous systems are compact and ideal for apartments or small offices where gas isn’t available. They are often installed “at the point of use” (like under a kitchen sink). However, keep in mind that larger whole-home electric units often require 3-phase power, which may require an electrical upgrade to your Melbourne property.

Do instantaneous gas hot water systems need electricity?

This is a common point of confusion. While these systems use gas to heat the water, the vast majority of modern instantaneous gas hot water systems do need electricity to function. They require a small amount of power to run the electronic sensor, the ignition, and the digital temperature controller. This means that during a total power outage, your modern gas instantaneous system generally will not work unless it has a specialized battery backup.

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Choosing the Right Size for Your Home

When we talk about the “size” of a tankless system, we aren’t talking about its physical dimensions (which are typically about the size of a small suitcase). Instead, we refer to the flow rate, measured in litres per minute (L/min).

What size instantaneous hot water system do you need?

Choosing the right flow rate depends on how many outlets (showers, taps, dishwashers) you expect to use at the same time:

• 1 Bathroom (1-2 people): 16 – 20 Litres per minute.

• 2 Bathrooms (3-4 people): 24 – 26 Litres per minute.

• 3+ Bathrooms (Large family): 32 Litres per minute.

If you choose a unit that is too small, the water pressure or temperature might drop if someone starts the laundry while you are in the shower.

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The Cost of Installation in Melbourne (2026 Estimates)

Because these units require precision gasfitting and often new electrical connections, the upfront cost can be higher than a standard electric tank.

How much is an instantaneous hot water system?

In 2026, the total cost for a professional Instantaneous Hot Water Installation in Melbourne typically ranges between $2,200 and $4,500. This generally includes:

• The high-quality unit (brands like Rinnai, Rheem, or Dux).

• Materials and valves.

• Professional labour and gasfitting.

• The mandatory Victorian Building Authority (VBA) Compliance Certificate.

While the upfront cost is higher, the long-term savings on your energy bills—since you aren’t heating water 24/7—often make it the more cost-effective choice over the life of the system.

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Why Choose King and Sons Plumbing?

Transitioning to an instantaneous system requires a licensed professional who understands both gas and water pressures. In Melbourne, where many older homes have smaller gas pipes, an upgrade to the pipework is sometimes necessary to fuel a high-powered tankless unit.

At King and Sons Plumbing, we bring over 25 years of experience to every job. We provide:

• Upfront Pricing: No hidden fees or “surprises” at the end of the job.

• Expert Sizing: We’ll calculate your peak water usage to ensure you never have a lukewarm shower.

• Rapid Response: We offer 24/7 emergency services across Melbourne for those times when your old system fails without warning.

Contact King and Sons Plumbing today to learn more about Instantaneous Hot Water!