Author: Joud Saad

Are you standing at the kitchen sink, waiting for the water to warm up, and wondering if your hot water system is on the blink? Or has it always been this slow? Maybe you’re shopping for a new system and want one that delivers hot water fast. Either way, how long does a hot water system take to heat up is a question on many homeowners’ minds.

From gas and electric storage tanks to instantaneous units, heat pumps, and solar systems, heating times vary based on:

• Hot water system type
• Hot water size
• Condition, & much more.

If you’re worried your system is taking far too long, or just curious about which option heats up quickest for those cold mornings in your birthday suit, this guide is for you. Let’s explore what affects heating times and whether it’s time to troubleshoot or upgrade with Link Plumbing in Sydney.

What impacts hot water heating time?

Before diving into specific systems, let’s unpack why heating times differ at all. Factors like system capacity, energy source, water starting temperature, and insulation all play a role. Our warm climate helps, as that cold incoming water is typically already 15- 20°C, but hard water or aging systems can slow things down.

If you’re asking how long does hot water system take to heat up because you’re waiting ages every single time you want hot water, it might signal a fault like a broken thermostat or sediment build-up. For hot water system shoppers, knowing how long does it take for hot water to heat up can guide you to a system that fits your lifestyle – whether you need instant hot water or can wait for a tank to warm up.

Heating times by system type

Here’s a breakdown of how long each major hot water system type takes to heat up. Whether you’re troubleshooting a sluggish system or comparing options, these insights will definitely help:

1. Gas storage tank systems

Gas storage tanks, common across Sydney but also all across Australia and beyond, store 90-170 litres of water heated by a gas burner. So, how long does a gas water heater take to heat up?

Typically, a 135L tank takes 30-45 minutes to heat water from 20°C to 60°C, assuming a healthy system. Recovery time (reheating after use) is similar but faster if only partially depleted.

BE AWARE: Slow heating might indicate a faulty burner or sediment, especially in older units.

2. Electric storage tank systems

Electric storage tanks (25-400L) use a heating element to warm water. How long does it take for an electric hot water tank to heat up?

A 125L tank takes about 2-3 hours to reach 60°C from 20°C, while smaller 50L units may take 1- 1.5 hours. How long does a electric hot water system take to heat up can depend on element wattage (eg. 3.6kW vs. 1.8kW) and insulation.

BE AWARE: If your tank’s taking longer, check the thermostat or element for faults.

3. Instantaneous gas systems

Instantaneous gas systems, or tankless units, heat water on demand. How long does it take for hot water to heat up with these?

Answer: Virtually instantly – within 5-10 seconds of opening the tap, water reaches 50-60°C, helped by Sydney’s warm water feed.

BE AWARE: Gas instant hot water system keeps turning off, or is it particularly slow to heat? That could point to low gas pressure or a clogged heat exchanger, requiring professional attention.

4. Instantaneous electric systems

Electric instantaneous systems also deliver hot water in 5-10 seconds, meaning you’ll never think ‘how long does a hot water tank take to heat up’ – because there’s no tank at all, just a powerful heating coil.

BE AWARE: Slow delivery might mean a faulty coil or insufficient power supply, especially in homes with older wiring.

5. Heat pump systems

Heat pump hot water units use electricity to transfer heat from the air, making them efficient … but slower.

For a heat pump, how long does hot water tank take to heat up if it’s an average 200L size? Expect 3-5 hours to heat from 20°C to 60°C, depending on ambient temperature. In Sydney’s mild climate, they perform well, but cold snaps below 5°C can slow them down.

BE AWARE: A sluggish heat pump might have a compressor issue or need refrigerant top-up.

6. Solar hot water systems

Solar hot water systems with electric or gas boosters are eco-friendly, but depend on sunlight. How long does it take for a hot water tank to heat up from cold if powered by the sun?

A 300L solar tank takes 4-6 hours to heat fully via solar panels, but the electric booster can cut this to 2-3 hours in cloudy Sydney weather.

BE AWARE: Slow heating might indicate a booster failure or dirty panels, which reduce efficiency.

Troubleshooting slow heating times

System definitely taking too long? It might not be just be its type. Here’s how to investigate:

Check Power/Gas Supply: Ensure gas valves are open or breakers aren’t tripped. Low gas pressure or power issues can slow heating.

Inspect Thermostats/Burners: Faulty thermostats (electric/solar) or burners (gas) can delay heating. Verify settings are at 50-60°C.

Look for Sediment or Scale: Hard water in Sydney can clog tanks, heat exchangers, or coils, slowing performance. Flushing may be needed.

Assess System Size: A small tank or underpowered instant unit might not keep up with demand, especially in large households.

Check System Age: Systems over 10-15 years old lose efficiency due to wear, corrosion, or outdated technology.

Did those checks resolve the issue? Or are you noticing:

• Leaks?
• Strange noises?
• Error codes?

If so, the time has come to call a professional – because slow heating often signals a need for maintenance or replacement, especially for older systems.

Choosing a system for speed

For those shopping for a new system, instantaneous or continuous flow technology – either gas or electric – is the fastest, delivering hot water in seconds, which is perfect for busy Sydney households. Gas storage tanks are quicker than electric for larger families, while heat pumps and solar systems trade a bit of speed for impressive efficiency. Consider your household size, budget, and energy priorities when choosing – and we’d always be happy to help make the right decision for your circumstances.

Link Plumbing – Your hot water experts

Troubleshooting a sluggish system? Or shopping for a faster one? Either way, Link Plumbing has you covered.

Our Sydney-based team specialises in diagnosing and repairing all hot water systems – from tanks to instant units, heat pumps, and solar. We’ll ensure your system heats up efficiently or help you choose the perfect upgrade. Don’t wait for hot water a second longer than you have to – contact the friendly team at Link Plumbing today for expert service!

Choosing the right hot water system setup can feel like guesswork, especially when your only reference is the tepid trickle that runs cold halfway through your shower. So what size hot water system do I need, we hear you ask? The answer depends on more than just the number of people in your home.

There are a lot of hot water system sizes, and what also matters to choose the perfectly-sized one is:

• Lifestyle
• Water usage habits
• Your appliance setup.

So here’s a simple, realistic guide to help you figure out which size system suits your situation – whether you’re a busy family of five, a homebody couple, or a minimalist single who only showers on alternate days (no judgement).

1. Singles, students, and light users (1 person)

If you live alone and tend to have quick showers, a compact system will usually do the trick. For electric storage, a 50L to 80L unit is often enough. If you use an instantaneous or continuous flow system, look for models with a 16L/minute flow rate.

Gas or heat pump systems may seem like overkill for one person, unless energy efficiency is your top priority.

Relevant to you:

• Low daily usage
• May use cold wash for laundry
• Often live in small homes or units with space constraints.

What size hot water tank do I need? For most singles: 50-80L electric or 16L/min flow rate.

2. Couples and small households (2 people)

For two adults sharing a bathroom (and likely a dishwasher), you’ll need a bit more capacity. In most cases, a 125L to 160L electric tank will do fine.

If you’re using gas or solar, system sizing depends on the number of outlets in use at once, not just the people. That’s where hot water system sizes vary more – it’s about flow rate and recovery speed.

What size hot water system do I need for a family of 2? Roughly 125-160L (storage) or 18-20L/min (continuous flow).

3. The average family (3-4 people)

This is where things get serious. A family of four doing morning showers, running the dishwasher, and nightly laundry will need a larger system – especially if everyone showers back-to-back.

What size hot water system for family of 4? Most experts recommend at least 250L for electric storage systems or a continuous flow unit rated at 24-26L per minute.

Keep in mind:

• Solar with electric booster may need more panel area but gives better efficiency long term.
• Instantaneous systems are great if you have gas and don’t want to worry about running out.
• Larger hot water tank sizes need room – so check your installation space before committing.

4. Bigger families or high-demand homes (5+ people)

If you’re dealing with a household of five or more, or even just a few teenagers who treat the bathroom like a private retreat, you’ll need something with grunt.

What size hot water system do I need for a family of 5? A 300L electric storage tank is usually the minimum. For gas continuous flow, 32L/min units (or two smaller units in parallel) are often recommended.

Don’t forget about recovery rate – the time it takes to reheat a tank after it’s been drained. Gas and solar tend to recover faster than electric, which can matter if your family all showers morning and night.

Hot water system size really counts here, especially if you’re in a busy household using multiple outlets at once.

5. Eco-conscious households

If you’re trying to reduce your carbon footprint, a heat pump or solar hot water system is your best bet – but size still matters.

Solar systems in Australia usually range between 250-400L tanks with electric or gas boosters. In sunny areas like Sydney, you can often run most of the year without relying much on the booster at all.

Electric hot water system sizes vary based on climate and orientation – solar requires enough north-facing roof space, while heat pumps work best in warm to moderate climates.

6. Low-usage homes (weekenders, investors)

If your property isn’t in use daily, you don’t need a full-size tank. Instead, focus on energy efficiency and compact design.

For Airbnb or short-stay rentals, 80L to 125L tanks usually cover basic demand. Tankless or hot water heater sizes with adjustable flow rates work well for variable occupancy.

7. Busy modern homes with multiple bathrooms

Even with just 3 or 4 people, some households push systems to the limit because of multiple bathrooms, bathtubs, and dishwashers all running at once.

This is where hot water system sizes Australia can be deceiving – it’s not just about litres, but also simultaneous usage. If two people are showering while the washing machine and kitchen tap are also running, a standard unit may struggle.

In this case, you’re not just asking what size water heater do I need – you need to consider hot water delivery infrastructure, including pipe sizing and water pressure.

8. People who love long showers (you know who you are)

If you take 20-minute showers or have a large bath you fill regularly, upsize. A bath can use 100-150L in one go. Add that to any other usage, and your hot water tank size becomes critical.

You might also want a system with a fast recovery rate – heat pump, gas, or even a solar booster.

9. Households running hot-water appliances

Some setups – washing machines, dishwashers – use hot water directly instead of internal electric heating. If that’s you, allow for an extra 50L/day usage on average.

This affects hot water tank sizes, especially for electric systems with slow recovery rates. Instantaneous systems handle this better, especially in climates like Sydney where demand fluctuates with the weather.

10. Upgraders switching from tank to continuous flow

If you’re ditching an old tank and want the benefits of endless hot water, you’ll need to convert your mindset from litres to litres-per-minute. The unit size in this case doesn’t look like a tank at all, but flow rate is key.

What size hot water system do I need?:

• A flow rate of 24L/min is a good minimum for families
• 26-32L/min is better for large households or multi-bathroom setups.

Just remember: continuous flow doesn’t store water – it heats on demand. That makes them space-saving and energy-efficient, but they do require adequate gas supply and pressure.

A few quick answers for the curious

Q: What size hot water system do I need?
A: Depends on people + lifestyle + usage habits.

Q: What size hot water tank do I need?
A: For 1-2 people: 80-160L. For 3-4: 250L+. For 5+: 300L+.

Q: What size water heater do I need for instant?
A: If using continuous flow, match to 16-32L/min flow rate based on how many outlets may be running at once.

Need help choosing the right size hot water system in Sydney?

At Link Plumbing in Sydney, we’ve helped thousands of households find the right system for their needs. Whether you’re upgrading, downsizing or building new, we’ll recommend the best setup for your home and lifestyle – with upfront fixed pricing, no surprises.

Call today for expert advice and same-day service.