What hot water system size do I need?

What is the best hot water system size for my home?

Every household’s hot water usage varies. This is why ensuring you get the right size system if you get a new hot water storage system is essential.

The hot water within a tank is affected by stratification, this simply means that the water temperature is affected by its location in a storage tank.

The higher the water in the tank, the hotter it will be, alternatively, the lower the water is, the cooler it will be.

Does size matter?

Size is crucial for hot water storage systems. Two reasons explain why this is the case.

First, if your system is too small, you will run out of water regularly. On the other hand, if your system is excessively large, you will spend unnecessary energy heating the water, so how do you know what hot water system size is best for you?

How to find the right hot water system size?

Also, when shopping for your new hot water storage system, there are three primary considerations – the technology, the volume and the capacity it can deliver.

Heat pumps are the way to go for larger systems

Nowadays, we recommend a heat pump and tank system as the best environmentally friendly technology to make hot water. The reason is that heat pumps use a low amount of energy compared to other methods of heating hot water. They can also be interlinked with a solar system and battery, so we can use renewable energy to heat our water.

What does the volume amount refer to?

Volume refers to the amount of water the tank can hold simultaneously. This is usually what the tanks are advertised as, a ’50L tank’, which means the tank can have 50 litres of water, however, the volume of a tank does not need to be the amount that can be provided at one time.

For example, it can be okay if you have a 50L tank but usually use 60L of hot water daily. This is because if you use 20 litres of water three times spread out throughout the day, the tank can refill, reheat and provide enough water. Unfortunately, such a small system can not be purchased with heat pump technology, and a simple electric hot water system is the best option in such a case.

Determine how much you use in a single go

This is where the capacity of water the tank can deliver at one time is more critical. If you find how much water you and your family use throughout the day, you can save money and energy by purchasing an appropriate tank for the family’s needs.

To calculate your daily needs, please consider that a decent 7-minute shower uses between 60 and 70 litres of water, of which about 40 comes from the hot water tank and the rest from the cold water supply. Hand washing the dishes depends on the unique method, but allow about 40 litres of hot and 30 l of cold water – to mix. Depending on how full you like, a bath can use between 70 and 180 litres of water, with about 2/3 coming from the hot water supply.

Please also consider which time of the day the various family members use the hot water and allow for the time it takes to reheat it, for example, heat pumps take about 1 hour to heat 100 litres of water.

Considerations for hot water system size

So, to correctly size a hot water storage system, you need to determine your water consumption patterns. Whether you find this by using your water meter, checking consumption over a week, allowing 50% cold and 50% hot water supply, or attaining a professional for advice is up to you.

Usually, we recommend adding 10-20% of your regular water consumption when purchasing a storage system to account for days when you may use more than usual, as you do not want to run out.

By doing this, you can ideally find the right hot water system size for your home, saving you energy in the long run. If you live in a multi-person household, the general recommendation regarding tank size is as follows: