Hot Water Cylinders

Hot water cylinders come in all shapes and sizes and it’s up to you which you go for, depending on your home’s needs.

However, most installers advise people to have the largest one possible, especially with families. Of course, it’ll come down to how much room you have spare.

These cylinders have a capacity of anything from 100 to 300 litres so it’s always best to double check that your boiler will heat the amount of water available.

It would also be wise to ask how long it’d take to heat from cold, should you run out of hot water.

Whatever cylinder you purchase, you need to ensure it’s well insulated to maximise heat retention.

Nowadays cylinders come already insulated, but if you have an older model, it’s possible to buy an insulation jacket from most DIY stores. Any money spent on a jacket will soon be repaid through reduced bills.

Choosing a hot water cylinder

It’s a decision that shouldn’t be taken too lightly, as it’ll affect your home’s hot water system for years to come. Choosing the right one will save you extra money on your bills and provide your home with all your water needs.

Traditional hot water cylinder

This type of cylinder is very popular in the UK, serving a number of family homes in particular.

It can cope with a variety of different heating systems including electric, coal, oil and gas.

A cold water storage system, usually in the attic, supplies the cylinder a greater head of water. This means that taps have a higher flow rate, than when using a combination cylinder.

Combination hot water cylinder

The combination storage system has both a hot a cold water tank, one on top of the other.

Again, these can come in a variety of sizes, with the most common containing 115 litres of hot water and 20-115 litres of cold.

With a combination, it’s a good way to ensure you have a good supply of water when storage space may be limited.

The combination cylinder has a low maintenance, which makes it suitable for rented accommodation. It could also prove useful for home’s where the boiler is frequently drained and refilled.

Heating the water

There are three modes of heating to choose, and whichever you pick will determine whether a heat exchanger will be needed.

Direct water heating
Hot water simply travels straight through the cylinder, without the need for a heat exchanger. This can also be used for an electric heater immersion.

Indirect water heating
With indirect, there is a heat exchanger which the water passes through. This is contained within the cylinder and is usually coiled. It means that boiler water is not mixed with storage water.

Self priming water heating
This is a patented idea where a heat exchanger with two airlocks prevents water from mixing. It takes away the necessity of having a expansion and feed system for the primary circuit.

Size and storage of your water heating
The amount of hot water used all comes down to the size of the property and how many people are using it. The appliances used in the home will also have an effect.

Around 35-45 litres of hot water are used per person everyday. This comes out at 60-65 degrees centigrade.

  • Kitchen sinks use 0.20 litres per second
  • A bathroom sink will use 0.15 litres per second
  • A bath uses around 60 litres of hot and 40 litres of cold water
  • Showers use 11 litres of mixed water per minute.
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