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 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.
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
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.