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

Both regular and system boilers depend on cylinders for storing hot water, however, it’s absolutely your choice as far as choosing the type of cylinder is concerned.

Vented and unvented hot water cylinders differ in a number of ways. One of the most important difference between the two is the manner in which water is supplied to these cylinders.

In an unvented hot water cylinder, water is directly supplied from the mains, while a vent pipe is used to supply water to a vented cylinder, hence the name.

Hot water tank is generally stored in the loft as it depends heavily on gravity for pulling water down to the hot water cylinder and push it through the pipes installed in the house.

Vented Cylinders

In this type of cylinder, water is stored in a tank placed in the loft. The natural gravitational force pulls water through the vent pipe into the hot water cylinder that is typically positioned in an airing closet.

Once the water gets heated in the cylinder, it can either be consumed for heating your radiators or stashed for various domestic purposes, such as for bath or shower, washing clothes and utensils, etc. The water characteristically expands upon heating, and that’s where the tank in the loft and vent pipe come into play, for providing an exit route to the excess of water.

The pros

· A vented hot water cylinder is the cheapest and simplest option to both installation and maintenance.

· Your access to stored hot water continues even if the water supply is unavailable from the mains.

The cons

The major demerit of a vented hot water cylinder is that it heavily banks on the downward pull of the gravity. As a consequence, the height and distance of the cold-water storage tank decides the magnitude of pressure, the more the height and distance between your pipes and the tank, the more gravity pull will be exerted to pull the water with higher flow rate. It implies that taps upstairs will get less flow of water as compared to downstairs. And in such event, you might probably require additional pumps to be installed for fetching water far up.

Unvented Cylinders

In an unvented hot water cylinder, a cold-water storage tank is not required in the loft. The cylinder has direct connection with the main water supply line which implies that you get high level of pressure of your water and can significantly cut down on the middleman.

The water gets heated in the cylinder, however, unlike a vented hot water cylinder, there’s no tank or vent pipe to cope up with excess of water as it expands during the heating process. To address this, unvented cylinders come with built-in safety features such as an air bubble or expansion unit that’s inserted at the installation point at the top.

What makes unvented cylinders a perfect choice?

· Unvented cylinders come handy in balancing the pressures at cold and hot taps and showers. Higher water pressure gives more room and plenty of options for terminal fittings.

· If you are concerned about hygiene and potential health concerns that might be associated with water stored for longer periods for time, you must consider unvented cylinders to eliminate the risk of contamination since they don’t have a storage cistern.

· Hot water storage containers can be sited easily almost anywhere in commercial as well as residential properties since they are the default go-to option one storey abodes, such as flats and bungalows.

· Another major factor that inspires the use of unvented cylinders is that they generate less noise since the increase level of pressure tends to limit bubble formation which is the major cause of noise in vented cylinders. Not to forget unvested cylinders can be installed quickly and involve less pipe work.

The pros

· Unvented hot water cylinders do not require a water tank for storing cold water, which indicates that the system will occupy less space, is compact, and you get a flexibility to install it at a location that’s most convenient for you in your household.

· Unvented cylinders generally offer higher water pressure since they are fed with water directly from the main supply line at your home, but then, it largely depends on the strength of water flow at your mains.

· No tank means you are saved from the water getting contaminated or freeze in winters.

The cons

· Unvented hot water cylinders are based on complex and intricate technology and are, therefore, a bit on the expensive side when it comes to their installation and maintenance.

· Since these cylinders draw cold water directly from your mains, and if your main supply is turned off anyway, you won’t be getting any hot water.

· Almost always, unvented cylinders are not compatible with modern-day mixers and power showers.

So, Which Cylinder Should I Choose?

When choosing between an unvented and vented cylinder, you must carefully consider a number of factors. Some of the most important points to ponder while deciding the type of cylinder to install are listed below:

 What existing heating system and mains pressure are you working with?

If your house is an old one, there’re chances that you might be having a typical heating system and vented cylinders in practice. It is high time you understand that installing of an unvented hot water cylinder can deliver higher flow rate and water pressure as compared to your old network of radiators and pipes.

If water supply at your mains is sluggish, it won’t be a concern. But still, you can think about getting an unvented hot water cylinder since it’ll deliver water straight from your main water supply line at the same pressure.  If you’re experiencing pressure problems with your vented cylinders, you might consider going for an additional pump.

How Big is your house?

If you are short of space at your house and don’t have enough of it upstairs such as a loft, then you must avoid going for a vented cylinder. Storing cold water will become an issue for you and the water flow won’t be adequate if you can’t position the tank on a higher enough location to serve the gravity needs of vented cylinders.

A vented cylinder is the one you should go for if you have more than one bathrooms at your home since the cold-water storage tank offers adequate water without impacting the pressure and flow rate. An unvented hot water cylinder runs directly from the mains, and so if too many water taps are open, the flow and pressure can split and weaken.

What about the budget?

The simpler and more cost-efficient option to go for is a vented cylinder. Unvented hot water cylinders need specialized professional to install it and cater to its regular maintenance needs, which is important to ensure the cylinder keeps functioning at optimum levels.

However, installing an unvented hot water cylinder is hassle free and no pain. It doesn’t ask for much space and can be positioned almost anywhere at your residence.

Ongoing Costs

Running cost depends on the heating method you choose for your cylinders. Direct heating through internal elements such as in immersion heaters, which run on electricity, are comparatively expensive due to surging power bills than those based on indirect heating through an external heat exchanger or boiler power by solar or gas heating.