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What Size Instantaneous Hot Water System Do I Need?

More households in Australia are turning to instantaneous hot water systems to serve their hot water needs. Unlike traditional hot water units, an instantaneous hot water system is a tankless design that offers a more eco-friendly, space-saving solution to water heating. Like any hot water system, choosing the right size system for your needs is an essential consideration.

In this blog post, we’re offering some suggestions for choosing the right instantaneous hot water system for your household size.

Understanding Instantaneous Hot Water Systems

First things first: what exactly is an instantaneous hot water system? Instantaneous hot water systems work by having water flowing through an immersion heating element, meaning water is heated when needed rather than pre-heated and stored.

Unlike traditional hot water units, an instantaneous hot water heater doesn’t have a storage tank, which means it requires a lot less space. Storage tanks experiencing leakage, rust, or wear and tear are often the reason a traditional heater needs heating, so, by not having a similar storage system, instantaneous units tend to have longer lifespans.

With a storage tank-based water heater, the water needs to be kept at a certain temperature constantly to both provide water and reduce the risk of bacteria. As you can imagine, this requires constant energy usage. The instantaneous method of heating water when required is more energy efficient and can greatly reduce your electricity bills.

Determining Your Household’s Hot Water Needs

One of the key decisions to make when purchasing any type of hot water system is determining the size. Too small of a system, and your unit will struggle to meet demand, leaving you with some cold showers. Too big and you’ll be spending extra on initial and ongoing costs. So, how can you figure out the right size for you?

Everything will come down to how much water usage your home is likely to experience regularly. How many people are in your home, and what are their water usage habits like? Are there multiple bathrooms in your home and therefore a chance of simultaneous showers? What type of shower heads do you have? Consider the water consumption for your laundry (washing machines, sinks, etc.), kitchen (dishwashers, sinks), and bathrooms (showers, baths, etc).

For an instantaneous hot water system, the number of water outlets it has to accommodate will be key in choosing the right size for your home. You should also consider how often multiple outlets will be used at the same time and if you can take advantage of 3-phase power at your home.

Flow Rate and Temperature Rise

washing hands under tap

Measure traditional hot water systems by the capacity of the storage tank, measure instantaneous hot water systems by flow rate.

Flow rate is the speed at which your hot water system can deliver hot water to the necessary hot water outlets. To put it another way, a higher flow rate means water will be provided to appliances and fixtures more quickly. Measure flow rate in litres per minute (or gallons per minute in the USA). Most systems have a flow rate between 10 L per minute and 32 L per minute. Too low a flow rate can mean weak water pressure or even inconsistent hot water.

Temperature rise is the number of degrees incoming water needs to be heated to reach its desired temperature. For example, if water needs to be 50 °C but is 15 °C when it enters your heater, the temperature rise will be 35 °C. Once you calculate this, it’ll provide an idea of what your system needs to be able to achieve. A plumber or hot water expert can help you determine this.

Size and Specifications

Here is a guide to the flow rates we usually recommend based on the number of people in your home:

2 people: 20 litres per minute
3 people: 26 litres per minute
3+ people: 32 litres per minute

When looking for hot water systems, you need to make sure they are designed to work with your power source. For example, natural gas heaters won’t work if you’ve only got electricity available.

It’s important to always follow the manufacturer’s instructions and information when installing and operating your new system. Having a professional installation will provide the peace of mind that your system is installed properly and safely without voiding your warranty.

Energy Efficiency and Cost Considerations

The good news is that an instantaneous hot water system is going to be a more energy-efficient option than its traditional unit equivalent. While the initial price will be higher, in the long term you’ll save money on energy bills. Issues such as leaking, sediment build-up, and rust damage often cause the storage tank to need replacement in a hot water system. Having no storage tank is a major reason why instantaneous hot water systems have a longer average lifespan than traditional systems.

To help with energy efficiency, buying appliances and fixtures with good water ratings will help cut down your water usage and reduce the demand put on your hot water system.

Installation Requirements

Technician installing a hot water system

Whenever you install a new hot water heater, you’ll need to follow both manufacturers’ instructions and guidelines.

An instantaneous hot water system requires a more complicated installation than a traditional hot water unit. Even if you are handy with DIY, you should leave this job to the professionals to ensure your heater works safely and efficiently. It also means you don’t risk voiding your warranty.

Regular maintenance will help keep your system running smoothly, help you catch issues early, and give your plumber a chance to make any necessary repairs. Servicing helps increase not only the performance of your heater but also its lifespan.

Is An Instantaneous Hot Water System Right For You?

The right instantaneous hot water system can be a valuable addition to a small- or medium-sized family home. When you choose the right size, an instantaneous hot water unit provides an energy-efficient system that offers quick hot water when you need it.

Get Expert Advice From Same Day Hot Water Service

Same Day Hot Water Service is an Australian company that specialises in finding the right hot water systems for Aussie households. We offer our services all over the country, including in Brisbane, Sydney, the Gold Coast, the Sunshine Coast, Canberra, Melbourne, and the Central Coast. Having helped a range of household sizes with finding the right system, we are confident we can help with all your hot water needs.

Get in touch with our friendly, expert team today to discuss your hot water needs!

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