How to choose the right size of hot water system

How to choose the right size of hot water system

When it comes to choosing the hot water system that is right for you, taking into account its size is an important factor. Certain hot water systems are larger than others, regardless of the size of your holding tank. There are three main types of hot water system to decide between.


While an electric hot water system is usually cheap and easy to install into your home, it can be expensive to run. An electric hot water system works best with a large tank. This is because your hot water is heated overnight. In order to make your water last all day, you will need that larger tank. You could go with a small tank but if you do then you run the risk of having no hot water to do the dishes at night or for an evening bath.


Gas hot water systems often provide instantaneous hot water. This means you don’t need a tank and you can have hot water on demand. If space is an issue and you have access to gas then this is a good choice. On top of this, gas is a much more efficient energy source. However, different systems are more energy efficient than others so make sure to check the ratings before committing to a purchase. It is worth keeping in mind that in the event of a power cut, electric ignition gas hot water systems won’t work (neither will electric-only systems). If you live in an area prone to blackouts, you should consider a pilot light gas system instead.


Solar powered systems can save you a lot of money. However, for them to be most effective they need to be fitted where they are going to catch the most sun. If you don’t have anywhere with lots of sun, a solar power system may not work well for you. Like an electric system, they require a tank and you will likely want to opt for a large tank so you can still access hot water on less sunny days. It is worth checking to see if the solar hot water system comes with a gas or electric booster to help top up your heating when it is less sunny. Without this option, you might be left without hot water.

However, if you have a gas booster then you can have a solar powered system that heats your tank but instant hot water when you need it through your gas. In this way, a solar powered system can be the best of all worlds. It can provide a tank full of hot water, heated for free, and instant hot water when really needed.

Which is best for you?

When it comes down to it, your living space, your hot water system budget, and access to gas will dictate the type and size of your hot water system. However, if you can afford the installation costs of a solar powered hot water system then it can take care of around 90% of your hot water needs for free. While gas has cheaper running costs than electric, if you want something even cheaper in the long run, then solar power is the way to go. However, if you need a hot water system installed quicking and cheaply, then electric is the way to go.

In summary

Electric - cheap to install, costly to run, large tank size, water heated overnight
Gas - costly to install, cheap to run, no tank, instant hot water
Solar - expensive to install, almost free to run, large tank, instant hot water