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Let’s evaluate which cylinder is better in the vented vs non-vented cylinders Choice.
Hot water cylinders keep hot water on hand and heat it up when it’s needed.
As materials and components get advanced, there are more high-quality cylinders to choose from than ever before. The type of heating system and cylinders you choose depends on your budget and home type.
There are two kinds of hot water cylinders: those with vents and those without. Whether you have a system boiler (not vented) or a normal boiler (vented), your heating system will need a different type of hot water cylinder.
Vented Cylinders
Vented systems are defined as gravity-fed hot water systems.
These cylinders are often also called open-vented cylinders. They need to be fueled by a big tank of cold water kept in the loft. This water flows through a vent pipe and into the hot water tank, which is heated by gravity.
The cold water tank’s height and the vented cylinder’s gravity sets the pressure. The greater the height, the more powerful the water flow. This means that the cold water tank should be installed in the loft.
As the water is warm, it increases, but the vent pipe and tank in the loft provide an exit route for the extra.
Traditionally, open cylinders were made of copper, as they were thought the best way to store hot water and provide adequate heat transfer. However, the heat loss from an open copper cylinder sparked a national effort to cover and insulate hot water tanks throughout the UK.
Manufacturers now pre-spray protect the tank to reduce heat loss.
Alpha offers a diverse range of boilers to suit various needs, including combi boilers, system boilers, and regular boilers. Combi boilers are ideal for smaller properties, providing heating and hot water on demand. System boilers are suitable for homes with multiple bathrooms, offering enough hot water supply. Regular boilers, also known as heat-only boilers, are compatible with traditional heating systems, ensuring consistent warmth throughout the house.
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Unvented Cylinders
Unvented hot water systems vary in that they don’t require a water collection tank. Instead, the cold water mains feed a sealed hot water tank.
An unvented tank is kept under pressure from a receiving water source. The water is heated directly by immersion heaters (a direct model) or a heat source outside the tank, such as a boiler or wet solar system (an indirect model).
Outlet pipes attached to the tank spread the hot water to various outputs around the house. As soon as an outlet (tap, shower) is used, the pressure of the entering cold water displaces the hot water volume in the cylinder towards the open outlet at mains pressure.
Unvented systems are sealed, needing an expansion tank either next to or inserted within the boiler or cylinder. An expansion tank allows for the growth of water in the system as it heats up and handles the increase in pressure by up to 4.5%.
Unvented cylinders are intended to withstand great internal forces and are extremely safe to use when supplied with all the right pressure equipment.
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What’s the Difference Between Vented vs non-Vented Cylinders:
Vented hot water cylinders, or vented hot water storage units, need to be fed from a cold water holding tank kept in the loft. The water moves down from the tank via a feed pipe to the bottom of the hot water cylinder.
As the water is warm, it increases, but the vent pipe and tank in the loft provide an exit route for the extra. This extra water goes through the vent pipe and back into the cold water storage tank in the loft. The exit line will also remove any air at the top of the hot water tank.
Unvented tanks, on the other hand, are hooked straight to the mains. This avoids the need for a cold water tank in the loft, which is why they need to be put alongside a system boiler. You’re essentially cutting out the middleman, and your water flow should be greater.
Unlike Vented vs non-vented cylinders don’t have a vent pipe or tank to cope with extra water as it heats and expands. Unvented cylinders have inbuilt safety measures to address this, like an expansion unit at the top or an air bubble introduced at installation.
Both unvented and vented cylinders can be heated directly by an immersion heater in the cylinder, indirectly by a boiler, or as part of a solar thermal system. Many homes use a boiler to heat the water indirectly but have an immersion heater as a backup in case of a boiler breakdown.
Choosing the Right Hot Water Cylinder
When making a choice between a vented or an unvented cylinder, you need to think about a few key variables:
What Existing Heating System Do You Have?
The older your home, the more likely it is to have an open hot water tank and a regular heating system. This is important to understand, as adding an unvented cylinder could cause higher water flow than your old network of pipes and radiators can handle.
How Strong is the Main Pressure?
If your mains pressure is low, you must consider whether adding an unvented tank is the best choice, as it will provide water straight from the mains at the same low pressure. Some people with vented cylinders who have problems with low main pressure will install an extra pump to boost the flow.
How Big is Your House?
Do you have lots of space, ideally in an extra area like a loft? If the answer is no, then an open cylinder is probably not for you. You will struggle to store the large cold water tank in a high enough position to give the system the necessary pressure.
An open cylinder may be better if you have two or more bathrooms. This is because the cold water tank gives lots of water simultaneously with no effect on pressure. An unvented tank rests on the flow of the mains, which, if directed to too many outlets at once, will split and weaken. This shouldn’t be a problem in homes with up to two bathrooms.
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What Size Hot Water Cylinder Do I Need?
It’s essential that your cylinder is big enough to handle your home’s hot water needs but not so big that it wastes energy heating and saves far more water than you need.
The cylinder size is generally measured in litres, which doesn’t mean much to most people. The easiest way to determine your need is to base it on the number of bedrooms, bathrooms, and showers. The volume you need will change slightly based on whether you are directly or indirectly heating the water; this is because cylinders that are heated by boilers (indirectly) tend to reheat quickly.
Industry experts use the below numbers as a guideline:
Bedrooms | Showers / Bathrooms | Indirect (litres) | Direct (litres) |
1 | 1 | 75/120 | 120/150 |
2 | 1 | 150 | 180 |
3 | 2 | 180 | 210 |
4 | 2 | 210/250 | 250/300 |
Larger Properties | 300+ |
Best Hot Water Cylinders
When you’ve decided on the ideal type and size of cylinder, your next choice will be which brand to choose. Several brands of cylinders are available in high quality at reasonable prices.
Here are the top hot water cylinder names in the UK today:
Cylinder Model | Sizes Available (volume in litres) | ErP Rating (Energy Efficiency) | Heating Method | Heating Method |
Megaflo Eco by Heatrae Sadia | 70 / 125 / 145 / 170 / 210 / 250 / 300 | B | Indirect or Direct | Lifetime |
Megaflo Eco by Heatrae Sadia | 90 / 120 / 150 / 180 / 210 / 250 / 300 | B | Indirect only | 25 years |
Megaflo Eco by Heatrae Sadia | 90 / 120 / 150 /180 / 210 / 250 / 300 | C | Indirect but includes a backup immersion heater | 25 years against corrosion |
StainlessLite by Gledhill | 90 / 120 / 150 180 / 250 / 300 / 400 | C | Indirect or direct | 25 years |
Tempest by Telford | 90 / 125 / 150 / 170 / 200 / 250 / 300 | C | Indirect or direct | 25 years |
Bottom line
We hope this article has helped you understand the difference between Vented vs non-vented cylinders hot water cylinders and given you some things to consider when choosing a cylinder for your home.
However, unvented stainless steel hot water cylinders are a better choice for new installs and replacing old ones. They ensure a vast amount of stored hot water is ready on demand for many home uses. Operating at mains pressure often increases flow rates to enjoy better shower and bath performance all year round.
People Also Ask
Off course! You can choose to use an unvented cylinder in a vented system. If it takes time to replace your vented hot water cylinder and you want to switch your house to an unvented one day but do not have the means, this method may ensure you can replace your new cylinder when ready to convert and stretch out the conversion expense.
Direct hot water cylinders heat water directly, but both vented vs non-vented cylinders can be direct or indirect. Additionally, indirect hot water cylinders heat water using an external source, such as a boiler.
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