Most hot water cylinders used to be made of copper and weren’t very well insulated, you could insulate them by covering with a red jacket that had insulation inside but they still tended to lose a lot of heat.

These are basically a storage facility for your hot water requirements. Choosing the right one for your home is important as you don’t want to spend out the money again because you chose the wrong size. You can either choose stainless steel or copper cylinders, there are a lot out there on the market so you have plenty of choice. A lot of them come with a 10 year guarantee from date of installation which is a good selling point when making your decision.

You will hear the term direct, in-direct, vented, unvented, so i’m going to go through the different types to clarify everything for you.

Vented cylinder

Vented hot water cylinder

Vented hot water cylinders are fed from a tank in the loft. Every time you use hot water from the taps the cold water tank in the loft automatically fills the hot water cylinder. They are normally made of copper and the standard size is 210 litres the amount it takes to fill a bath.

They are only used for hot water so just have an outlet at the top of the hot water cylinder. There is also a larger hole to insert an immersion heater.

Unvented Cylinders

Unvented hot water cylinder, indirect, direct, storage of hot water,

unvented hot water cylinder, storage of hot water

This type of cylinder has mains water directly running through it. Instead of a tank in the loft, mains water runs right into the bottom of the cylinder. The hot water comes out at the top as soon as hot water is drawn from any of the utilities. The good thing about this type of cylinder the water is mains pressure out the taps, very common in most modern homes

Indirect Cylinders

The water travels through the central heating pipes into the the hot water cylinder around a coil and the water that’s inside the tank gets heated up as the central heating water circulates. You normally have a programmer that has hot water only or central heating only, when you push the hot water button a valve by the cylinder switches the water so it travels through the cylinder instead of the radiators giving you hot water only. If you have the central heating button on at the same time another valve will open so the water circulates around the heating system also.

Hot water cylinder, unvented hot water cylinder, water cylinder, direct hot water cylinder, indirect hot water cylinder
Direct unvented hot water cylinder

hot water cylinder
Unvented hot water cylinder

Are Unvented Hot Water Cylinders Safe?

Hot water creates a great deal of pressure within an unvented cylinder. If this builds up to dangerous levels, the tank could split. A pressure relief valve helps prevent this from happening by allowing excess pressure to be vented. If the valve fails, this cannot happen, though.

Unvented Hot Water Cylinders G3 (Builders)

G3 UNVENTED CYLINDER HEATING SYSTEMS Qualified INSTALLER. Unvented cylinder heating systems must be installed by a competent and qualified G3 qualified engineer

What Is The Difference Between Vented And Unvented Hot Water Cylinders?

A vented cylinder has a tank in the loft which feeds the hot water cylinder in the airing cupboard. The problem with this type of system is the pressure is not very good and needs a pump to give you better showers etc. which can be noisy especially first thing in the morning.

An Unvented cylinder is much better as it feeds off mains pressure so no need to have a seperate tank feeding with water. This means you get really good pressure at all your tap outlets and you will get a high pressured shower.

How Much Is An Unvented Hot Water Cylinder?

They range from around £300 – £3000 depending on the size and the manufacturer. We can go over how many bathrooms you have and people living in your home to decide the best litre capacity.