If you have ever asked yourself, “How do continuous flow hot water heater work for my home?” you are not alone. Many Sydney homeowners want an efficient, reliable way to enjoy warm showers on demand. The good news is that continuous flow units (often called tankless or demand water heaters) heat water only when you need it, saving energy and ensuring you never run out of hot water in the middle of your morning routine. In this guide, you will discover how these systems operate, why flow rate matters, and how to choose the right option based on whether you have gas or electricity. Let’s explore the basics so you can make a confident decision for your home.
Discover the basics
A continuous flow hot water heater warms water on demand, rather than storing it in a tank. When you switch on a hot water tap, cold water travels through a pipe into the unit. The heating element (gas burner or electric coil) instantly warms the water en route, delivering a steady flow until you turn the tap off.
How it differs from a storage tank
Traditional storage tank heaters keep hot water in a large reservoir, constantly reheating to maintain temperature. This can lead to:
- Standby heat loss (using energy to keep water hot when not in use)
- Limited supply (once the tank empties, you wait for more hot water to heat up)
Continuous flow systems avoid these pitfalls by heating only as required, which can trim energy bills over time, tankless water heaters can be 24%–34% more energy efficient if your household uses 155 litres or less of hot water daily.
A closer look at the heating process
- Cold water in: Once you turn on a hot tap, cold water enters a heat exchanger.
- Rapid warming: An electric coil or gas burner ignites (if gas-fired) or powers on (if electric).
- Hot water out: The heater adjusts output so you get a near constant supply of warm water.
Because no tank is needed, these heaters free up space—handy in smaller homes or for those who want a streamlined design. They also have a longer lifespan than standard tank heaters (often more than 20 years) because there is no stored water causing corrosion in a tank.
Calculate your flow needs
Flow rate—measured in liters per minute (LPM)—reveals how much hot water a heater can supply at once. For continuous flow systems, this number becomes essential. If your household has multiple fixtures running simultaneously (such as a shower and washing machine), you want a heater that can keep pace.
Gauging your household’s demand
Each fixture and appliance has a typical LPM. For example:
- Standard shower: 7.0–10 LPM
- Kitchen sink: 5.5–7.5 LPM
- Dishwasher: 3.75–5.5 LPM
- Washing machine: 5.5–7.5 LPM
To find your peak hot water demand, list every fixture your family might use at once, then add up their LPMs. If you end up with a combined total of, say, 18 LPM, that is the minimum flow rate you need for uninterrupted hot water.
Why GPM matters
If a heater’s output does not keep up, you could face lukewarm water in your shower when someone runs the tap in the kitchen. Continuous flow heaters typically provide 7.5–18 LPM, with gas units often offering higher flow rates than electric ones. This means:
- Small households (2–3 people) can do well with a 7.5–11.5 LPM unit.
- Larger families may consider a 15–19+ LPM solution or even multiple units.
Understanding your flow rate requirements keeps you from selecting a system that ends in temperature drop-offs or underperformance.
Temperature rise counts, too
Groundwater temperature plays a big role in how quickly the heater can warm your supply. Sydney’s climate is moderate, but if you live in a cooler zone or you have chilly winter groundwater, the heater will need more power to achieve your preferred hot-water temperature. Be sure to check the specifications: a higher temperature rise demand usually requires a higher capacity unit.
Consider gas or electric
Both gas and electric continuous flow systems heat water instantly, but they do so in different ways.
Gas-fired options
Gas units rely on a burner. When you open a hot tap:
- A gas valve opens.
- The burner ignites.
- Heat transfers quickly to the water via the heat exchanger.
These systems typically produce higher flow rates, making them attractive to larger households. They also avoid the standby losses seen with tank models. However, you need a gas supply and sometimes proper ventilation if you are installing the unit indoors. If you are curious about how these units work, you can read more at how do continuous flow gas water heaters work.
Electric units
Electric continuous flow heaters use high-powered heating elements. When the tap is on:
- An internal sensor detects water flow and activates the electric element.
- The element instantly warms the water passing through the unit.
- The system shuts off once you turn off the tap.
They are simpler to install in homes with no gas piping but tend to have lower LPM ratings. That does not mean they are inefficient—many are still quite energy-smart for smaller households, especially in mild climates. If you want further insight, check out how do continuous flow electric hot water heaters work.
Comparing continuous flow with tank systems
Below is a quick table highlighting the strengths and potential trade-offs:
| Feature | Continuous Flow | Storage Tank |
|---|---|---|
| Heating method | Heats water as needed | Stores heated water in a tank |
| Typical flow rate | 7.5–19 LPM (gas higher, electric slightly lower) | Matches tank size (e.g., 100–300 litres) |
| Energy efficiency | 24%–34% more efficient (small demand) | Some energy lost through standby heating |
| Space requirement | Compact, often wall-mounted | Larger footprint due to tank |
| Lifespan | 20+ years with proper care | Around 10–15 years |
| Upfront cost | Higher initial price | Lower purchase cost, but higher long-term |
It is clear that continuous flow heaters can offer great advantages if your household meets the flow rate requirements and you can handle the upfront investment.
Plan installation and upkeep
Getting the most out of your continuous flow hot water heater involves more than simply picking the right flow rate. Proper installation, care, and occasional maintenance can keep your system running smoothly for years.
Professional consultation
Continuous flow units have specific needs, including:
- Adequate gas or electrical connections
- Correct ventilation (for gas)
- Sizing according to your peak LPM
Improper installation can reduce efficiency or shorten the unit’s lifespan. For safety and peace of mind, consider hiring a certified plumber or heating specialist. They will ensure your new heater meets local building codes and is placed in a spot that helps heat water efficiently.
Routine checks
A continuous flow system usually lasts longer than a standard tank, but to help it reach or exceed its 20-year milestone, plan routine checkups:
- Flush mineral buildup: Over time, minerals can collect inside the heat exchanger. A yearly flush helps preserve performance.
- Inspect connections: Check wiring (if electric) or gas lines (if gas) for any signs of wear.
- Test performance: Turn on multiple fixtures and see if you still get consistent temperatures.
Scheduling these checks keeps your heater running at peak efficiency and reduces the likelihood of unexpected breakdowns.
Watch for signs of trouble
Although continuous flow heaters generally perform well once installed properly, keep an eye on:
- Sudden temperature fluctuations (if your LPM was correctly calculated, everything should stay steady)
- Pilot light issues on gas models (look for an intermittent ignition device that helps save energy)
- Strange noises or error codes on your control panel (if equipped)
Early detection of minor glitches can prevent costlier repairs down the road.
Recap and next steps
Continuous flow hot water heaters give you a steady supply of hot water when you need it, helping you save energy by eliminating standby losses. They are typically more efficient than storage tanks (24%–34% more for smaller daily demand), last longer, and provide almost endless hot water—so long as you have the right flow rate.
Here is a quick summary of how to choose and maintain your system:
- Identify your total LPM needs by adding up the water demand for showers, sinks, dishwashers, and laundry.
- Decide whether gas or electric fits your home’s existing setup and lifestyle.
- Plan for proper installation, possibly with a professional, to maximise efficiency and meet local codes.
- Flush and inspect the system regularly to extend its lifespan and keep your water comforting and warm.
If you feel ready to enjoy all these benefits, reach out to JSW Plumbing. They will make sure you get the right continuous flow hot water heater for your home. You will have confidence that your new system is installed to the highest standard, so you can keep warm water flowing for many years to come. Feel free to get started today.
