Category: Home Appliance

Hot water cylinders are used to store hot water in a home, business or any general building that needs hot water services. There is also a need for them in some heating systems. There are a few different kinds of hot water cylinders, and each of them has its specific uses. There are direct and indirect systems, as well as vented and unvented cylinders. Knowing the difference and what uses each of these kinds of water heaters has, you will be able to know which one will best fit your home.


Direct hot water cylinders heat the water using a heating element that is found within the cylinder. In a direct hot water cylinder, the cold water enters from the bottom. The water is then heated using the immersion heater, and the hot water is pushed out the top of the cylinder. Direct hot water cylinders are pretty simple and don’t take up as much space as an indirect system, but you cannot use an outside source or boiler alongside this system, so you can’t use more efficient ways of heating the water, like solar power.


Indirect hot water cylinders heat the water using a heating element found outside the cylinder, located in a boiler next to the cylinder tank. The water from the boiler is then sent through a coiled tube on the inside of the cylinder. That coil is what heats the water on the inside of an indirect hot water cylinder. It isn’t uncommon for indirect cylinders to have a backup heating element on the inside. These kinds of systems are generally more versatile. They can be heated using various methods, such as solar power, which will save on the electricity bill.

Vented Cylinder

Vented cylinder water heaters rely on a cold water tank to push water into the cylinder to be heated up. This kind of system relies on gravity to work, so it is often found in the upstairs of a home. Furthermore, you might need to install a pump in order to get good water pressure in the upstairs was rooms. Vented cylinders usually have built-in special taps that can release the pressure that builds up as the cylinder heats. That is why vented systems don’t need an expansion tank.

Unvented Cylinder

Unvented cylinders use the main water supply instead of a cold water tank. Because it is using the main supply, the water pressure is much better than a vented cylinder. Unfortunately, an unvented cylinder is usually more expensive to own and maintain than a vented cylinder since there are more safety mechanisms, such as relief valves and different thermostats that can control the temperature. Unvented cylinders also need expansion tanks that can stop pressure build-up inside the water cylinder as the water heats and expands.

There are many different ways that you can use each of these kinds of hot water cylinders, and each kind of system has its pros and cons. All homes have a system already in place, but if you need to replace your cylinder, you should be able to tell the difference between each kind and recognise which one would be best for your house. In some places using a direct vented water heating systems will be a perfect fit, and in other places, an unvented and indirect cylinder would be more appropriate. The factors that come into place are location, how many people live in the house, how much space is in the house and how much you are willing to spend on a water heating system.

Read more