What size hot water cylinder do I need?

Posted: 24th November 2024 | Author: Adam Brown | Category: Heating

Choosing the correct size of hot water cylinder is essential for ensuring your household has a steady supply of hot water while avoiding unnecessary energy costs. Too small a cylinder, and you risk running out of hot water at inconvenient times. Too large, and you’ll waste energy heating water you don’t use.

Whether you're upgrading your current system or installing a new one, the correct cylinder size will depend on key factors like the number of people in your home, your water usage habits and your budget. This guide will help you to understand all the variables to consider when choosing your new hot water cylinder.

How big should my hot water cylinder be?

As mentioned above, you will need to take a number of things into account when deciding on what size hot water cylinder to go for. Opting for a size that suits your specific needs will help you save both money and energy. You should consider your household size, water usage habits and budget for installation and running costs.

Number of people/rooms in the house

The number of people living in your home and the number of bathrooms directly influence your hot water requirements. Households with more people and multiple bathrooms need larger cylinders to meet higher water demand. The size you need can also depend on how your hot water cylinder works, i.e. whether it’s a direct or indirect system.

We recommend the following sizes based on your household:

Frequency of hot water use

Your daily habits significantly impact the size of the cylinder you need. High-demand households require larger tanks to avoid interruptions in supply, while lower-demand homes can get by with smaller, more energy-efficient models. According to the Hot Water Association, a home with low consumption uses 20-30 litres of hot water per person per day. For average consumption, it’s 30-50 litres and high consumption is 50-70 litres.

There are a number of things in your home that use hot water. The most obvious is your shower or bath. When calculating the frequency of your hot water use, it’s worth thinking about how frequently everyone showers or takes a bath. You should also take into account how long people’s showers last.

Different appliances in the home also use hot water, such as dishwashers and washing machines. If your household tends to use these appliances simultaneously, you may need a larger hot water cylinder to provide enough hot water for multiple tasks at the same time, preventing any interruptions.

Installation budget

If you are planning to install a hot water cylinder, you may be aware that installation isn’t cheap. The size and type of hot water cylinder can have a direct impact on installation costs which may factor into which cylinder you choose to go for. Larger cylinders, for example, are typically more expensive to install, and they may require additional considerations such as larger storage spaces or structural reinforcement.

It is essential that your hot water cylinder is installed by a qualified plumbing and heating engineer. There are two types of hot water cylinders:

• Vented cylinders

These systems are generally less expensive to install but require a cold-water storage tank, often located in the loft. This adds to space and plumbing requirements, which can lead to further costs.

• Unvented cylinders

These do not need a separate tank, as they connect directly to the mains water supply. They provide excellent water pressure and are well-suited for modern homes. However, they often come with a higher installation cost due to the need for specialist fittings and safety measures.

Running costs budget

Beyond the initial installation, the cost of running your hot water cylinder depends on its size, efficiency and insulation. Larger cylinders can lead to higher energy bills if they are oversized for your needs, as they continuously heat unused water, which is why it’s important to select the right size cylinder for your home.

If you are looking to lower your running costs, there are a few things you can try:

• Look for energy-efficient cylinders with high energy ratings and built-in insulation
• Insulate your cylinder with foam or an insulation jacket to retain heat more effectively
• Invest in renewable energy options such as solar thermal panels or heat pumps to significantly reduce running costs
• Schedule your heating so you only heat the water when you need it
• Use less hot water by taking shorter showers or ensuring the dishwasher is completely full before putting it on.

The Author: Adam Brown

With a background as a Mechanical Engineer, I started Nationwide Supplies alongside my brother with a vision to modernise what seemed a stuck-in-its-ways industry in the builders merchant sector.  Since 2011 it has been my goal to source quality products at the correct prices to be able to offer a saving to customers along with high quality customer service which offers quick delivery and superior technical knowledge in the industry.  

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