Vented vs. Unvented Hot Water Cylinders: Which One Should You Choose?

21 May

If you have a regular boiler or system, a domestic hot water cylinder is important for daily activities. Mainly, there are two types of cylinders. These include a vented and an unvented hot water cylinder, each with a central heating system and specific properties.

Vented Cylinders

These are traditional cylinders because they have been there for many years and are among the first models to use copper. Now readily available in stainless steel and copper, vented hot water cylinders heat and store water, which is directly fed from the tank in the loft. Because the tank in the loft is often located high from the ground, it provides gravitational force, enabling water to flow to the outlet of the tap throughout the house.


  • They are cheaper to maintain and install because they’re basic.
  • If the main supply of water is cut off, you can still get access to the water tank in the loft.
  • It is a more preferred option if property owners don’t want to pay for upgrades to unvented system.


  • Requires a storage space in the loft for cold water tanks.
  • Installation of vented systems hardly deliver hot water.
  • Water pressure mainly depends on the cold water tank’s height – meaning showers and taps upstairs often have weaker flow of water than those in downstairs.

Unvented Cylinders

Unvented cylinders are tanks, which directly provide hot water to showers, taps, and other appliances upon request. Unlike vented systems, unvented cylinders are completely sealed and directly takes water from the main water source. This means these cylinders offer a more consistent and higher flow rate and don’t depend on gravitational force to work. A sealed cylinder and absence of the loft in the tank protects households from nuisance frozen pipes, removes risks of contaminated water, and saves you invaluable space. For that reason, homeowners regard them as more hygienic systems than vented cylinders. Not to mention, they are quieter cylinders since there is no sound of refilling water in the cold tank.


  • No freezing
  • More space for storage
  • Less noise
  • Possible to install anywhere


  • More complex to maintain and install
  • High costs of repairs and servicing

Making the Right Decision

Deciding which cylinder is a suitable option narrows down to your maintenance, space, requirements, and budget. For a homeowner with a small budget, it will be a great idea to invest in a vented hot water cylinder. It is less complex and much easier to maintain. The installation is also easier and will cost you less. However, if maintenance, money, and space isn’t an issue, unvented systems are suitable options for you. Because slimline and horizontal options are available, you can install them anywhere in the property, whether it’s a tight airing place or loft. Plus, vented cylinders take care of everything by simply providing optimal performance and mains pressure throughout the property.

In conclusion, an unvented hot water cylinder is a better option for a new installation as well as replacement of an existing one. But it would be best to go for the right type so as to avoid compatibility problems.