What Size Hot Water System Do I Need

Last updated on January 15, 2024

When looking at hot water systems for your home, it’s crucial to think about the size.

You might wonder, “How can I know what size hot water system I need?

Many people think bigger is always better, but that’s not always true. A too-big system can lead to higher energy bills and possible water pressure problems.

On the other hand, if you end up with a system that’s too small, it might struggle to handle your family’s hot water needs. But don’t stress! In this blog post, we’ll take you by the hand and help you find the ideal size for your hot water system.

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The Importance of Choosing the Correct Size Hot Water System

Selecting the right size hot water system for your home is extremely important.

Why, you ask?

Well, if you’ve got the right size system, you’ll always have enough hot water for everything you need.

Be it for a warm bath, doing your laundry, or tackling that pile of dishes; a suitably sized system means you don’t have to deal with unexpected cold shocks.

Second, picking a system that fits your needs is essential for optimizing energy efficiency. If your water heating system is oversized, it will consume more energy than needed, leading to expensive energy bills.

On the other hand, a too-small system will have to strain to satisfy your hot water needs, resulting in heightened energy usage.

Lastly, the correct size hot water system also ensures adequate water pressure. If your system is too large, it can put unnecessary strain on your pipes and fixtures, leading to reduced water pressure.

Understanding Different Factors That Influence Hot Water System Size

Determining the size of your hot water system involves several factors to keep in mind. Consider the size of your household, how many bathrooms you have, the number of people using water simultaneously, and your day-to-day hot water usage.

It’s crucial to remember just how important water is in our daily homes. Think about those busy mornings when everyone’s trying to get ready for work or school. It’s during these times that the water demand is at its highest.

Therefore, having a hot water system that can cope with these high-peak demands without running out is of utmost importance.

Also, don’t forget to account for the degree of heating needed. This means figuring out the gap between the current water temperature and desired water temperature.

If you reside in a cold area where you usually need to heat water considerably, it’s crucial to select a system that can effectively meet this need.

It’s also a good idea to consider how efficient your chosen hot water system is. Look for ones that have high energy efficiency ratings. This way, you can be sure you’re not wasting energy and keeping your costs low.

Finally, think about any changes in your home that could affect how much hot water you use.

Are you expecting new household members? Or do you plan on adding an extra bathroom or replacing your old appliances? These things can influence the size of the hot water system you’ll need.

A Step-by-step Guide to Determine Your Hot Water System Size

Now that you understand the importance of choosing the right size hot water system for your home, let’s dive into a step-by-step guide to help you determine the perfect size.

Calculate your household’s peak hot water demand. This would be at the busiest time of day when everyone is using hot water simultaneously. Consider activities like showering, running appliances, and washing dishes.
Determine the degree of temperature increase needed by measuring the difference between the temperature of incoming cold water and the desired hot water temperature. Consider the climate and whether you’ll need a more extensive system to achieve the desired heating level.
Evaluate the efficiency of different hot water systems. Look for models with high energy efficiency ratings to minimize waste and lower energy costs.
Consider any future changes to your household. Are you expecting to expand your family or upgrade appliances? These factors can impact the size of the hot water system you’ll need.

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Exploring Various Types and Sizes of Hot Water Systems

Now that you’ve grasped the importance of selecting the right-sized hot water system for your home and have a helpful guide to figure out the ideal size, let’s dive into the different types and sizes available in the market.

Different households have specific needs, and luckily, hot water systems come in various sizes and types to meet these demands. The types you’re most likely to come across include storage tank systems, tankless systems, and heat pump systems.

Hot water size guide

Gas storage hot water system

Household size	Gas storage hot water heater size
1 – 3 people	90 litre
2 – 4 people	130 litre
3 – 5 people	170 litre
4 – 6 people	200 litre

An instant gas water heater can operate with natural gas or LPG. Its size isn’t determined by how many people live in the house but by how many faucets might need hot water at the same time.

For instance, if your home has two bathrooms and a kitchen that all require hot water simultaneously, particularly during peak times like the evening, you should consider acquiring a unit with a 24-liter capacity to guarantee an adequate supply of hot water for all the taps.

Number of outlets	Gas instant hot water
1	16 litre
2	20 litre
2 – 3	24 litre
3 or more	32 litre

Solar hot water size guide

Solar hot water systems only heat water during the day. Most systems are fitted with either an electric or gas booster for high demand times or overcast days.

Number of people	Solar hot water system size
1 – 2	180 litre
3 – 4	300 litre
5 – 6	440 litre

Heat pump hot water size guide

Heat pump water heaters are very energy efficient, even more so if connected to an economy tariff (off-peak 1 or off-peak 2).

Small – less than 200L	Medium – 200 – 300L	Large – 300L+
Apartment or small house	Average sized house	Large house
1-2 bedrooms & 1 bathroom	3 bedrooms & 1 bathroom	4 or more beds & 2 or more bath
Maximum 2 people	Maximum 3 people	Minimum 4 people
Not normally suited to off-peak tariffs	May not be suited to off-peak. Some can run on Restricted hours tariff	Restricted hours and off-peak tariff possible

Reference- https://www.energyrating.gov.au

Final Thoughts

Storage tank systems are the traditional choice, where hot water is stored in a tank for immediate use. These systems come in various sizes, ranging from small tanks suitable for apartments to large tanks for big households.

As discussed in our guide, you can determine the right size heating system for your household by considering peak demand, desired heating level, system efficiency, and the future needs of your household.