A hot water cylinder (a water heater or hot water tank) is essential to your home’s plumbing system. It provides hot water for showers, washing dishes, doing laundry, and more. These insulated tanks store and heat water, keeping it ready for use throughout your home.
In New Zealand households, several hot water cylinders are standard, including electric, gas, immersion heaters, and solar-powered systems. Each has its heating efficiency and timing, which we’ll explore in detail throughout this guide.
Factors That Affect Heating Time
Before discussing the specific heating times for different hot water cylinder types, it’s essential to understand the factors influencing how quickly water heats up.
Size/Capacity of the Cylinder
One of the most apparent factors affecting heating time is the size of your hot water cylinder:
- Small cylinders (100-135 litres): Heat up faster, but store less hot water
- Medium cylinders (180-200 litres): Provide a balance between heating time and storage capacity
- Large cylinders (250-300+ litres): Take longer to heat but can supply more hot water for larger households
Naturally, a 300-litre tank will take significantly longer to heat from cold than a 100-litre tank using the same heating method.
Type of Heating System
The heating method has perhaps the most significant impact on how long your hot water takes to heat:
- Electric immersion heaters: Generally slower but widely used
- Gas boilers: Typically faster than electric options
- Heat pumps: Energy-efficient, but can have variable heating times
- Solar systems: Dependent on weather conditions and often paired with backup heating
Starting Water Temperature
The initial temperature of the water entering your cylinder plays a crucial role. During winter months in New Zealand, incoming water is colder, requiring more energy and time to reach the desired temperature.
Insulation and Heat Loss
A well-insulated hot water cylinder retains heat more efficiently. Older cylinders with poor insulation take longer to heat up and cool down faster, requiring more frequent reheating.
Thermostat Setting
The higher your thermostat is set, the longer it will take to reach that temperature. For safety and efficiency, most hot water cylinders in New Zealand are set between 60°C and 65°C.
Typical Heating Times by Cylinder Type
Now that we understand the factors affecting heating time, let’s look at the approximate heating times for different hot water cylinders standard in New Zealand homes.
Electric Hot Water Cylinders
Electric hot water cylinders are among the most common in New Zealand homes. They use an electric element (similar to a kettle) to heat the water.
Average heating times:
- A standard 3kW element will heat a 180-litre cylinder from cold in approximately 2-3 hours
- A smaller 100-litre cylinder might take 1-2 hours
- A larger 250-litre cylinder could take 3-4 hours or more
The wattage of the heating element significantly impacts heating time. A higher-wattage element (e.g., 6kW) can heat water almost twice as fast as a standard 3kW element, but these are less common in residential settings due to electrical supply limitations.
Gas-Heated Cylinders
Gas hot water cylinders generally heat water more quickly than electric systems, making them popular for larger households with high hot water demands.
Average heating times:
- A standard gas-heated 180-litre cylinder can heat from cold in approximately 30-60 minutes
- Smaller cylinders (100 litres) might heat in just 20-30 minutes
- Larger cylinders (250+ litres) typically take 60-90 minutes
Gas systems can be either direct or indirect. Direct systems heat the water directly in the cylinder, while indirect systems heat water in a boiler that then transfers heat to the cylinder via a coil. Indirect systems are slightly slower but often more efficient over time.
Immersion Heaters
Immersion heaters are electric heating elements that are inserted directly into the hot water cylinder. They’re often used as a backup to another heating system or in cylinders specifically designed for them.
Average heating times:
- Similar to standard electric cylinders: 1-2 hours for a 100-litre tank
- Typically 2-3 hours for a 180-litre tank
- Can be up to 4+ hours for larger tanks
Many homes have dual immersion heaters that can be used together for faster heating or separately to heat just a portion of the tank when less hot water is needed.
Solar Water Heaters
Solar hot water systems use energy from the sun to heat water, making them environmentally friendly but somewhat dependent on weather conditions.
Average heating times:
- During sunny days: 4-8 hours, depending on system size and sunlight intensity
- During cloudy days: May require backup heating from electric or gas systems
- Seasonal variations: More efficient during summer months than winter
Most solar systems in New Zealand include a backup heating source for cloudy days or when demand exceeds what the solar system can provide.
How to Speed Up Heating Time
If you’re finding that your hot water cylinder takes too long to heat up, there are several strategies that might help:
Use of Timers and Smart Thermostats
Installing a timer or smart thermostat allows you to heat water during off-peak electricity hours while ensuring it’s ready when you need it. This is particularly useful for electric cylinders.
Regular Maintenance and Descaling
Limescale buildup on heating elements can significantly reduce their efficiency. Regular maintenance by a qualified plumber from Ur Plumber can keep your system working optimally.
Proper Insulation
Adding a cylinder jacket or upgrading to a better-insulated model can reduce heat loss, meaning your cylinder stays hotter for longer and requires less frequent reheating.
Upgrading to a Faster or More Efficient System
If your hot water needs have changed or your current system is ageing, upgrading to a more efficient model or a different heating type might be worth considering. Ur Plumber offers a range of modern, efficient hot water solutions tailored to your needs.
How to Know Your Cylinder is Fully Heated
It’s helpful to know when your cylinder has reached its set temperature:
Thermostat Cut-off
Most cylinders have a thermostat that automatically cuts off the heating element or gas supply when the desired temperature is reached. You might hear a click when this happens.
Water Temperature at Taps
The most obvious sign is consistent hot water from your taps. If the temperature begins to fluctuate or cool, your cylinder may need more heating time.
Cylinder Indicators or Smart Systems
Some modern cylinders have indicator lights or can connect to apps that show the current water temperature and heating status.
Conclusion
So, the answer to how long for a hot water cylinder to heat up in New Zealand homes varies significantly based on the type of system, size of the cylinder, and several other factors. Electric cylinders typically take 1-4 hours, depending on size. Gas systems are faster, at 30-90 minutes, while solar systems rely heavily on weather conditions.
Understanding your specific system’s heating time helps you manage your hot water usage more efficiently and can alert you to potential issues when heating times suddenly change.
For optimal performance, consider regular maintenance from qualified professionals, proper insulation, and potentially upgrading older systems to more efficient models.
Need Help With Your Hot Water Cylinder?
At Ur Plumber, we specialise in all aspects of hot water cylinder installation, maintenance, and repair across Auckland. Our experienced team can help you choose the right system for your needs, upgrade your existing cylinder, or troubleshoot heating issues.
Don’t put up with long heating times or inefficient systems. Contact Ur Plumber today at 027 856 7712 for expert advice and service from Auckland’s trusted plumbing professionals.
We also stock a comprehensive range of quality plumbing supplies, parts, and fixtures in our online store.
Frequently Asked Questions
How long does a hot water cylinder take to heat up?
A 100-litre electric hot water cylinder typically takes 1-2 hours to heat from cold, while a gas-heated 100-litre cylinder might heat up in just 20-30 minutes. For precise information about your specific system, contact our team at Ur Plumber for a professional assessment.
Is it cheaper to leave the hot water on all the time?
Timer controls are more economical than constantly leaving the heating on for most modern, well-insulated cylinders. Ur Plumber can help you install and program efficient timer systems that match your household’s hot water usage patterns, saving you hundreds of energy bills annually.
Can I shower while the cylinder is heating?
Yes, you can use hot water while the cylinder is heating, but be aware that this will extend the overall heating time. If the cylinder is only partially heated, you may run out of hot water during your shower. Ur Plumber can recommend appropriately sized systems for larger households that meet your family’s needs.
How can I tell if my hot water cylinder is working efficiently?
Signs of an inefficient cylinder include increasingly long heating times, running out of hot water quickly, or unusual noises from the tank. If you notice any of these issues, Ur Plumber’s certified technicians can conduct a thorough assessment and recommend solutions ranging from simple maintenance to system upgrades.
Do heat pump water heaters heat up faster than standard electric cylinders?
Heat pump water heaters typically take longer to heat than standard electric cylinders, but use significantly less electricity (up to 60% less). If you’re considering this energy-efficient option, Ur Plumber offers expert installation and can help determine if it’s suitable for your home.