How to Choose the Right Gas Hot Water System
Not sure how to choose the right gas hot water system for your home or business? You’re not alone. Whether you’re upgrading an old unit or starting fresh, picking the best system can feel overwhelming—especially when you’re trying to balance comfort, cost, energy efficiency, and long-term reliability.
This guide breaks it all down in plain language. We’ll walk you through everything you need to know to make a confident, informed decision—backed by real-world advice from experienced Sydney plumbers.
Here’s what we’ll cover:
- Why Your Choice of Hot Water System Matters
- Types of Gas Hot Water Systems Explained
- How to Choose the Right Size and Capacity
- Installation Considerations (and What to Expect)
- Cost Breakdown: What to Budget For
- Long-Term Considerations: Maintenance and Reliability
Let’s start by looking at why your choice of system makes such a big difference.
Why Your Choice of Hot Water System Matters
Choosing the right gas hot water system isn’t just about ticking a box—it directly affects your comfort, your energy bills, and how smoothly your household or business runs day to day. Whether you’re taking a hot shower after work, running a busy café kitchen, or managing a rental property, your hot water system needs to keep up with demand—efficiently, safely, and reliably.
That’s why getting the right system for your needs isn’t just a nice‑to‑have—it’s a smart investment. A mismatched or outdated system can lead to cold showers, higher power bills, or even early breakdowns that leave you scrambling for a replacement.
For example, we recently helped a family in Ryde switch from an oversized storage unit to a continuous flow system. Their previous unit was using more gas than needed for a four‑person household, and they were constantly running out of hot water during peak times. With the new system properly matched to their household water heating needs, they’re now enjoying reliable hot water—and lower running costs.
If you’re a business owner, the stakes are even higher. A salon or café can’t afford hot water disruptions. Instant hot water demand is critical, and downtime means lost revenue. That’s why system selection for commercial spaces needs to factor in both usage patterns and plumbing compliance for gas appliances.
Key takeaway: The right gas hot water system isn’t just about keeping the water warm—it’s about long‑term comfort, efficiency, and peace of mind. A good fit means lower bills, fewer headaches, and reliable hot water when you need it most.
Types of Gas Hot Water Systems Explained
When you’re looking to choose a gas hot water system, one of the first decisions is between two main types: storage and continuous flow (also known as instantaneous).
Both have their place, and the best choice depends on your home or business needs—especially how much hot water you use, when you use it, and how important energy efficiency is to you.
Let’s break down how each system works and who they suit best.
Storage Gas Hot Water Systems
How They Work:
A storage system heats water in a tank and keeps it hot until you need it. It’s like having a reservoir of hot water on standby, ready for use. These systems come in a range of sizes, usually from 90L to 300L or more, depending on your household or commercial requirements.
When It’s a Good Fit:
- You have a larger family or multiple bathrooms and need hot water across different times of day.
- Your home uses off‑peak energy tariffs to reheat water overnight.
- You prefer a system that can deliver large volumes of hot water quickly, especially during morning or evening rush hours.
Real‑World Example: In a recent install for a family of six in Blacktown, we recommended a 315L storage gas system to handle simultaneous showers, dishwashing, and laundry. The key was durability—these units are designed to handle heavy daily use without skipping a beat.
Key Considerations:
- Takes up more space
- Higher standby energy usage (because water is kept hot around the clock)
- Known for their durability and straightforward maintenance
Continuous Flow (Instantaneous) Systems
How They Work:
Instead of storing hot water, continuous flow systems heat water only when you turn on the tap. The water runs through a heated coil, delivering hot water on demand—so you’re not limited by a tank.
When It’s a Good Fit:
- You want energy efficiency and lower running costs
- You live in a smaller household or use hot water more evenly throughout the day
- You run a business with variable hot water demand, such as a café or clinic
- You’re limited on space, like in a townhouse or apartment
Key Considerations:
- Heats water as you need it—no running out
- Compact and wall‑mounted
- Ideal for instant hot water demand
- May struggle with multiple outlets used at once (though this depends on the unit size)
Quick Comparison Table
| Feature | Storage System | Continuous Flow System |
| Water Supply | Stored in tank | Heated on demand |
| Energy Use | Higher standby energy use | More energy‑efficient |
| Space Required | Larger footprint | Compact, wall‑mounted |
| Best For | Families with high peak‑time use | Smaller homes or staggered water use |
| Running Out of Hot Water | Possible during high demand | Not likely (endless supply) |
| Durability | Proven longevity | Fewer parts, lower wear |
| Upfront Cost | Generally lower | Slightly higher depending on model |
Key takeaway: There’s no one‑size‑fits‑all system. If you have high, consistent hot water use—like a busy family home—a storage unit may be ideal. If you value energy efficiency, need hot water only as needed, or have limited space, a continuous flow system could be the better match.
How to Choose the Right Size and Capacity
Once you’ve decided between a storage or continuous flow system, the next step is choosing the right size and capacity. This decision is crucial—go too small and you’ll run out of hot water when you need it most. Go too large and you could end up wasting energy (and money) heating water you never use.
Let’s look at what you should consider whether you’re outfitting a busy family home or a small commercial space.
For Residential Homes
The Key Factors:
When sizing a gas hot water system for your home, consider:
- Number of people in the household
- How many bathrooms you have
- Whether you tend to use hot water all at once (e.g. everyone showers in the morning)
- Whether you run appliances like dishwashers or washing machines at the same time
As a general rule:
- A 2‑person household might be fine with a 16L–20L continuous flow unit or 90–135L storage tank
- A family of 4 will likely need a 24L continuous flow or 160–250L tank
- Larger families or homes with 3+ bathrooms might require a 26L+ flow unit or 315L+ storage system
Example: A 3‑bedroom home in the Inner West with 2 bathrooms and four people showering between 7–8am would benefit from a 26L continuous flow unit with strong flow capacity, or a 250L storage system if they prefer peak‑time supply without any temperature drops.
Efficiency Matters: understanding and comparing water heater energy ratings helps keep your bills in check.(see Australian consumer info on water heating energy ratings)
For Small Businesses or Commercial Spaces
The Key Factors: Commercial spaces don’t just need hot water—they need compliance, reliability, and zero downtime. System size depends on:
- Type of business (e.g. café, salon, medical clinic)
- Number of sinks or hot water outlets
- Frequency and duration of hot water use
- Whether hot water is used steadily or in bursts
Example: We recently fitted out a small café in Marrickville with a 32L continuous flow gas system to cover handwashing, dish cleaning, and prep area needs. It replaced an under‑sized unit that couldn’t keep up during weekend rushes.
For salons or medical clinics, it’s critical to meet hygiene standards while ensuring the system is strata‑approved and installed by a licensed professional. Choosing a system that aligns with your business’s water use—and meets all plumbing compliance for gas appliances—helps avoid costly disruptions later.
Bonus Tip: Some strata and council guidelines require specific energy ratings or safety features in shared or commercial properties. It’s worth checking early—In House Plumbing can help navigate these requirements.
Key takeaway: Getting the size right is just as important as choosing the system type. Whether you’re managing a family household or running a business, properly sizing your gas hot water system ensures efficient performance, fewer breakdowns, and no unpleasant surprises when the hot water runs out.
Installation Considerations (and What to Expect)
Installing a new gas hot water system isn’t just about picking the right unit—it’s also about understanding what happens next. From council approvals to access issues and installation timelines, knowing what to expect can help the process go smoothly and avoid last-minute surprises.
Let’s break it down step by step.
Do You Need Council Approval or Safety Checks?
In some cases, yes. Depending on your property type, location, and the type of system you’re installing, you may need to meet local council requirements—especially if you’re replacing an electric system with gas or upgrading a unit in a multi-dwelling building.
For example:
- Strata properties often require written approval before making changes to shared infrastructure
- New gas connections or relocating a system may need council sign-off or inspection
- Certain installations must comply with energy efficiency targets set by state or council guidelines
Beyond council rules, it’s vital your installation meets plumbing compliance for gas appliances under Australian Standards. This includes safe placement, ventilation, and use of certified parts.
That’s why it’s essential to work with licensed gas fitters in Sydney who understand both local council regulations and national safety codes. At In House Plumbing, we handle all compliance paperwork and ensure every job is up to code—from first connection to final sign-off.
What About Solar Panels, Roofing, or Guttering?
Hot water system installation often overlaps with other elements of your home or business—especially if the unit is installed externally.
Here’s what to watch for:
- If you have solar panels, the location of your gas unit must allow access for both systems. Some solar and gas setups can work in tandem (solar for daytime, gas for boost), but not all are compatible.
- If your unit is wall-mounted or outdoors, rooflines and guttering can affect placement and ventilation.
- Tight spaces or awkward access points (like alleyways or side yards) may require additional brackets or piping solutions.
Our team frequently installs gas hot water systems in homes with solar setups and tricky access. For instance, we recently completed a job in the Northern Beaches where we had to temporarily remove a gutter guard to safely position a wall-mounted continuous flow unit—without disrupting the solar inverter nearby.
Tip: If you’re unsure whether your current layout will work, we’re happy to inspect and provide tailored options.
Installation Time, Access, and Property Layout
So how long does it take? In most standard residential installs, we can replace or install a gas hot water system in half a day to one full day. More complex jobs—like new gas connections or relocating units—may take a little longer.
Key factors that affect installation time include:
- Access to the install location (e.g. side gates, upstairs units, tight alleyways)
- Whether it’s a like-for-like replacement or a full upgrade (e.g. electric to gas)
- The need for regulatory compliance inspections or permits
- Site-specific adjustments, like drilling, re-piping, or reinforcing walls
We always follow safe gas installation standards, ensuring everything is properly sealed, vented, and tested before we leave. Our team cleans up after the job, too—because no one wants to deal with leftover mess or scrap parts.
Key takeaway: Professional installation isn’t just about hooking up a system—it’s about making sure everything is safe, compliant, and suited to your property. From navigating council requirements to working around roofing and solar setups, a smooth install starts with the right plan.
Cost Breakdown: What to Budget For
Understanding the costs involved is a big part of choosing the right gas hot water system. Whether you’re replacing an old unit or planning a new install, knowing what to expect upfront helps you avoid surprises and stay in control of your budget.
Let’s break down the key costs—and how to keep them in check.
Average System and Installation Costs
So, how much does it cost to install a gas hot water system in Sydney?
Here’s a general guide based on current industry averages:
- Storage gas hot water systems: From $1,200 to $2,500, including supply and standard installation
- Continuous flow (instantaneous) systems: From $1,500 to $3,000, depending on capacity, brand, and complexity
These prices include the unit, labour, basic materials, and removal of your old system (if applicable). If you’re switching from electric to gas or adding a new gas line, expect additional costs for gas fitting and compliance work.
Tip: While upfront costs are important, don’t forget to factor in ongoing efficiency. A slightly higher initial spend on an energy-efficient hot water system can save you significantly over time on running costs.
What Can Affect the Total Price?
Every property is different, so total costs can vary based on several factors:
- System size and type – Larger tanks or high-capacity flow units cost more
- Access to the install site – Tight spaces or second-storey installs may require extra labour
- Plumbing or gas upgrades – New connections, rerouting, or old pipe replacements add cost
- Council or strata compliance – Some jobs require permits, inspections, or approvals
- Energy efficiency rating – Higher-rated units may cost more but reduce bills in the long run
It’s also worth considering the running costs of gas hot water systems. Continuous flow units tend to be more energy-efficient because they heat only what you use. Storage systems, while effective for high-volume use, can use more energy maintaining a full tank of hot water 24/7.
If you’re a business owner, keep in mind that commercial gas hot water system selection must also meet safety and usage compliance, which can influence cost.
How to Avoid Hidden Costs
No one likes surprise charges. That’s why at In House Plumbing, we prioritise transparent, upfront pricing. When we quote a job, we include:
- The full scope of work (not just the base install)
- Materials and labour
- Any council or compliance requirements
- Removal and disposal of old units
- GST and other applicable fees
We also explain what might cause a price to increase—such as unexpected pipe issues or access restrictions—before work begins. That way, you’re not caught off guard mid-job.
Our customers often tell us that this level of clarity helps them feel more confident and in control—especially after dealing with tradies in the past who left them guessing.
Key takeaway: Gas hot water system costs can vary, but a clear, detailed quote can take the stress out of budgeting. Look beyond the sticker price—consider energy efficiency, installation needs, and who you’re trusting to do the job right.
Long-Term Considerations: Maintenance and Reliability
Choosing the right gas hot water system is only part of the story. To make sure your system runs efficiently and lasts as long as possible, it’s important to understand what’s involved in long-term care. A well-maintained unit not only performs better—it also saves you money on repairs and energy in the long run.
Here’s what you need to know to keep your system in top shape.
Servicing and Maintenance Needs
Like any appliance, gas hot water systems benefit from regular check-ups. Ongoing maintenance of gas hot water systems helps catch minor issues before they turn into major problems—and ensures the system is running safely and efficiently.
Recommended servicing frequency:
- Every 1–2 years for continuous flow systems
- Every 3–5 years for storage systems (or sooner if under heavy use)
What a standard service might include:
- Checking for gas or water leaks
- Inspecting and flushing the pressure relief valve
- Cleaning or replacing filters
- Testing temperature and pressure settings
- Reviewing overall energy performance
Typical servicing costs range from $150–$300, depending on the system type and service depth. While it might be tempting to skip it, regular maintenance extends the lifespan of your system—and helps avoid expensive breakdowns.
Signs of Wear or When to Replace Your System
Even with proper care, no hot water system lasts forever. Most gas systems last around 10–15 years, depending on usage, water quality, and upkeep. If your system is reaching that age or showing signs of wear, it might be time for a replacement.
Watch for these warning signs:
- Water takes longer to heat or runs cold unexpectedly
- Unusual noises (popping, gurgling, or hissing)
- Rusty or discoloured water
- Visible leaks or moisture near the unit
- Sudden spikes in your gas bill
- Hot water running out faster than usual
As part of our plumbing inspections, we assess whether your current unit is still safe and cost-effective—or if upgrading would save you more in the long run. In many cases, replacing an old, inefficient system reduces running costs significantly.
Trusted Repairs and Advice from Local Experts
If something goes wrong with your system, knowing who to call can make all the difference. At In House Plumbing, we’re known across Sydney for reliable, no-fuss repairs and honest advice you can count on.
We’ve helped customers all over—from quick fixes in Parramatta to full replacements in Sutherland. Whether it’s a minor issue like a leaking valve or a full system failure, our team of licensed technicians will assess the problem, explain your options clearly, and only recommend what you actually need.
You’ll always get local plumbing expert advice, not a rushed job or a sales pitch. And because we know how disruptive hot water issues can be, we respond quickly—with same-day service available for many repairs.
Key takeaway: A gas hot water system is a long-term investment—but like any investment, it needs care. With regular servicing, early attention to issues, and expert support from a trusted local plumber, you’ll get the best performance, safety, and value from your system for years to come.
Conclusion: Make a Confident Choice with In House Plumbing
Choosing the right gas hot water system doesn’t have to be complicated. By understanding the different system types, sizing based on your property’s needs, planning for a smooth installation, and keeping long-term maintenance in mind, you can make a decision that delivers real comfort, efficiency, and value for years to come.
At In House Plumbing, we’ve helped hundreds of Sydney homeowners and businesses find the best fit for their hot water needs—whether that’s upgrading a family home in the Inner West or installing a new system in a busy café in the North Shore.
We believe in honest advice, upfront pricing, and plumbing solutions that work for your life—not just your pipes.Still unsure which system suits your home or business? Give us a call—we’re happy to help you decide.
Frequently Asked Questions
Reliability depends on both the brand and how well the system is matched to your needs. In Australia, trusted brands like Rinnai, Bosch, and Rheem consistently perform well in terms of durability, efficiency, and warranty support. The most reliable system is one that’s professionally installed, properly sized, and maintained regularly. At In House Plumbing, we only recommend systems we trust and have installed in homes and businesses across Sydney.
It comes down to how many people use hot water in your property, how often, and at what times. For example:
A couple in a small apartment might only need a 16L continuous flow unit.
A family of five with two bathrooms may require a 26L flow unit or a 250–315L storage tank.
For businesses, we consider daily demand and peak usage—like in a hair salon or medical clinic. We’re happy to assess your property and help choose a size that balances performance and efficiency.
Yes, it’s definitely possible—and often worthwhile. Switching to gas can reduce running costs and offer better water heating performance. The key factors to consider are:
Whether your property has an existing gas connection
Space and access for installation
Compliance with gas safety standards
Our licensed gas fitters in Sydney handle the entire process—from new connections to safe, compliant installations.
It depends on what type of system you’re installing and your property type. For most standard replacements, council approval isn’t required—but if you’re changing energy sources (like electric to gas), moving the unit’s location, or live in a strata property, approvals or compliance checks may apply.
We take care of all plumbing compliance for gas appliances and can guide you through any council or strata requirements to make sure everything’s done by the book.
For businesses like salons, clinics, or cafés, we usually recommend continuous flow systems because they:
Provide hot water on demand
Take up less space
Are energy-efficient for varying usage patterns
The best system also depends on your daily hot water usage, number of outlets, and compliance needs. We regularly install strata-approved hot water systems in commercial settings and can help you choose one that keeps your business running smoothly.
