Choosing a Water Heater: What Size Water Cylinder Do I Need?

5 Dec 2019

You need hot water for showers, washing up, doing dishes, and more. While the right brand of water cylinder will ensure that you have reliable operation and fewer hassles, you still need to ensure that you choose the right size for your needs. It’s actually pretty simple to determine what size cylinder you need for your family. We’ll walk you through everything below.

Why Does It Matter?

First, let’s address why size matters in the first place. While we are talking about physical dimensions, what we’re really discussing here is volume. The more volume the cylinder holds, the more hot water you’ll have at one time. That means more showers, more loads of dishes, etc. However, the larger the cylinder and the more water it holds, the more energy it will require to heat up to temp in the first place, which means your costs will be higher, too.

The Rule of Thumb

The UK’s Hot Water Association offers a good rule of thumb that may help you estimate the size of your hot water cylinder. In a home with low consumption, you’ll need 20 to 30 litres of hot water per person per day. In a home with average consumption, you’ll need 30 to 50 litres of hot water per person per day. In a high-consumption home, you’ll need 50 to 70 litres of hot water per person per day. However, remember that this is only for personal use – showering and the like. It does not include any other uses, such as heating.

General Size Considerations

In general, our recommendations for cylinder size are based on the number of bedrooms and bathrooms in your home. We’ve included a handy sizing chart below for your reference.

# of Bedrooms	# of Bathrooms	Cylinder Size in Litres
1	1	120 litres minimum
2	1	150 litres minimum
3	Up to 2	180 litres minimum
4	2	210 litres minimum
5 and up	2 and up	300 litres minimum

*Note that these sizes are for direct/unvented cylinders.

The chart above should at least give you a starting point. However, there are numerous factors that will influence the size of the cylinder you ultimately choose. For instance, do you use your cylinder for central home heating? For underfloor heating? The more uses the water is put to, the more volume you will need.

You will also want to factor in other things in your decision.

Number of People: Sometimes, the number of bedrooms does not accurately reflect the number of people living in a home. How many people live under your roof? How frequently do they shower or bathe?

Volume of Dishes: How often do you use your automatic dishwasher or wash dishes by hand? Again, this will be affected by the number of people in the household – washing up after a dinner for four will be very different from washing up after a dinner for six or eight people!

While we can help you find an estimated size, the best way to ensure accuracy is through a professional in-home assessment. Call EasyFlow today on 0161 941 5571 to schedule an appointment in Greater Manchester or Liverpool.

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