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If you live in a home with many bathrooms or a big family, then what your house needs is a heating system with ample capacity. That’s where the open vent boiler comes in. But what’s an open vent boiler, exactly? It is also known as a regular boiler. It has two water tanks, a cylinder for hot water, and a boiler, and provides heating and hot water.
It’s commonly used for larger homes. Because, unlike other systems, it can support more taps and showers being on and still be able to maintain its pressure.
What is an Open Vent Boiler?
An open vent is also known as a regular, heat-only, or conventional boiler. It is basically a heating system with the ability to heat and also for supplying hot water. However, unlike modern combi boilers, it requires extra components to work efficiently.
An open vented heating system consists of two tanks (which are commonly in the loft space): a cylinder of hot water, a purpose-built pump, and a boiler.
Because of this, it’s a very realistic alternative for larger homes with heavy water demand. As it is able to supply more taps and more showers at the same time. But because of its space requirements, it’s not very common in new homes.
Working of Open Vent Boilers Explained
An open vented heating system consists of a cold water cylinder. It is generally in the loft, supplying water into a hot water cylinder. The water from the cylinder is then heated up with the use of a boiler and supplied into radiators, taps, and showers when needed.
Here’s how it works step by step:
- The cold water tank fills up from the mains supply.
- It feeds water into the cylinder of hot water, where water is being heated.
- A pump delivers hot water to radiators when the heating is on.
- A feed and expansion vessel retains water levels in the system, replacing water lost from evaporation and leaks.
Since an open vented heating system relies on water in storage, the volume of water supplied will be limited by the capacity of the cylinder. If water runs out, you’ll need to wait for the tank to refill and reheat.
If you’re thinking of this style of system, referring to an open vented boiler system diagram can explain what every component does and how all the parts work together.
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What Type of Homes Need Open Vent Boiler Systems?
An open vented boiler system can be generally found in old homes with plenty of space for the installation of a loft-top tank. The systems take up more space compared to today’s combi boilers, and hence, they’re not common for small and newly built homes.
They are ideal for large homes with more than a single bathroom because they can heat and distribute hot water to more than a single shower and tap at the same time.
In an open vented heating system, preheated water is kept in a cylinder. With this, water temperature and pressure are not lost when there are more people utilizing taps and showers.
If you’ve got a big household or need a water heating system with heavy water usage, then an open-vent boiler could be your best choice.
How Do I Know If I Have an Open Vented Heating System?
It’s easy enough to tell if your house has an open-vented heating system. The signs are easy enough to spot.
- A feed and expansion tank (a small tank) in the loft.
- A cold water storage tank (a larger tank) also in the loft.
- A hot water cylinder (usually orange or white) in the airing cupboard.
- If your house has them, then your heating and water heating system has an open-vented boiler system.
Efficiency of Open Vent Boiler Systems
An open-vent boiler can heat water for more than one room without lowering water temperature and water pressure. Hence, this is a very convenient solution for homes with heavy water usage.
While combi boilers are more efficient, A-rated open-vented systems can also be acquired. Your system’s performance will depend on its compatibility with your house’s need for hot water.
With more people in a house, a combi boiler may not be able to keep up, while an open-vented heating system can handle the demand.
To improve energy efficiency:
- Insulate your hot water cylinder to keep water warm for longer.
- Using the heat from airing cupboards where the cylinder housing the hot water.
- Upgrading to A-rated, open-vent, if your heating installation is outdated and inefficient.
An open-vented boiler is worth it if it meets your heating needs. With energy-efficient upgrades, you can save on heating bills and still be able to use a guaranteed supply of hot water.
What is an Open Vent Boiler Combi Boiler?
An open vent and a combi are two very different heating systems.
An open-vent boiler, also called a heat-only boiler, has a circulating and heating cylinder and a cylinder for cold water. It’s ideal for large homes with two or more bathrooms because it can heat water for more than a single tap.
A combi (combination) boiler heats water directly from the main supply without the use of water storage tanks. So, therefore, it’s ideal for smaller homes where there isn’t enough space. But can be challenged when heating water for more than a single tap.
Difference Between an Open Vent and System Boiler
The main difference between a system and an open vent is their means of maintaining water pressure.
- An open-vent boiler relies on a feed and expansion tank, generally in the loft, for its pressure.
- A system boiler has its own integral expansion vessel and feeds directly from the mains, and therefore forms a sealed system.
A system boiler has fewer pipes and smaller space requirements, too, when compared with an open-vented system. However, both of them heat the water in a cylinder, unlike a combi boiler, where water heats directly.
Difference Between an Open Vent and Combi Boiler
The biggest difference between them is that a combi boiler heats water when needed, and an open-vented boiler heats water and keeps it in a cylinder for future use.
- Combi boilers don’t need a water cylinder and water tank for cold water, and hence, are space-efficient and ideal for small houses.
- Open-vented systems take up more space. But they supply multiple taps without lowering water pressure.
If you reside in a large house with more than a single bathroom, then an open-vented boiler will be more convenient. But if space becomes limited, then a combi boiler will be more convenient.
Best Open Vent Boiler
The best open-vented boilers are very durable, energy-efficient, and can be very long-lasting. They are best for use in homes where there’s a need for a constant supply of hot water for more than a single space. The best open vent boiler can be Vaillant ecoTEC, and others of them are Viessmann, Worcester Bosch, Baxi, and Ideal.
Vaillant ecoTEC Plus Open Vent Boiler
Vaillant is a quality brand when it comes to heating, and the ecoTEC Plus is one of their best open-vented boilers.
- Compact design – Easy for installation into a cabinet.
- Available in different sizes – Choose the best output for your residence.
- Highly efficient – Keeps your bills low.
- Easy installation – Rapid and easy fitting.
- Smart controls – Touch-pad programming for easy use.
- Warranty – 5-year standard guarantee (7 years if Vaillant Advance Installers install)
Viessmann Open Vent Boilers
Viessmann is renowned for its top-performance and durable boilers. Its range of open vents excels for:
- Strong build – Use of anti-corrosive stainless steel.
- Energy efficiency – To lower the usage of energy and save money.
- Quiet operation – Low noise levels make it ideal for home use.
- Smart control – Remotely controllable with the use of an app.
Best Open Vent Boiler Brands in the UK
If you’re looking for a reliable open-vent boiler, several well-known brands offer excellent options:
1. Worcester Bosch Open Vent Boiler
Worcester Bosch has a very good reputation for producing low-energy, quality boilers. Its range of open-vent boilers is best for traditional systems for larger homes. The boilers offer stable heat and firm water pressure, and they are a very good choice.
2. Vaillant Open Vent Boiler
Vaillant’s ecoTEC Plus range is compact and powerful, with top performance and easy installation. Vaillant has a broad reputation for its long-lasting, top-performance boilers.
3. Baxi Open Vent Boiler
Baxi open-vented boilers are not costly, but they are very reliable. They are easy to install and maintain, and hence, are ideal for homes with old heating systems needing replacing.
4. Ideal Open Vent Boiler
Ideal boilers have low-energy and low-cost solutions for homes with conventional heating requirements. Its range of products has quality heating performance and low bills.
If you’re buying an open vent boiler, shop for ones with the highest possible ratings for efficiency, solid performance, and fair warranties for the best value for your home.
Advantages and Disadvantages of Open Vent Boilers
Open-vent boilers are ideal for large homes with two or more bathrooms. There are, however, some downsides. Here’s a breakdown:
Advantages of Open Vent Boilers
- Easy to use and maintain: These boilers consist of fewer complex components, and hence, are simple to use and maintain.
- Ideal for larger homes: They can heat water for more than a single shower and taps at the same time. And hence, are best for large households.
- Works well with old heating systems: If your home has old radiators and pipes, then an open-vent boiler can be a viable alternative. It’s also optimal for low-pressure systems, unlike more modern unvented systems, which can lead to leakages on older pipes.
- Useful in emergencies: Since they maintain water temperature inside a cylinder, even if there’s a water supply disruption from the main, you can still use your water.
Disadvantages of Open Vent Boilers
- Takes up a lot of space: These boilers need a cylinder of hot water and a feed and expansion (F&E) vessel, generally in the airing cupboard and loft. Therefore, they are not best for smaller homes and flats.
- Not as energy-efficient as combi boilers: Heat can also leak from cylinders and storage vessels. And hence, they are not quite as efficient as combi boilers. This can result in higher bills.
- More expensive to install: Installation costs are higher compared to combi boilers. The installation can range from between £1,700 and £4,000, varying with the complexity of installation and the size of the house.
- Risk of contamination: The F&E tank can accumulate dust and debris over time, and this can contaminate water. Flushing and regular maintenance must be performed.
The Bottom Line
An open-vented boiler can be the perfect solution for large homes or for homes with multiple bathrooms that are older. It provides a continuous flow of water without changing temperature and pressure.
An open-vented boiler is also very energy-efficient and can be best for use with older piping networks. The best thing about them is that you can replace them with similar systems if necessary.
If your house has a very heavy demand for water for heating, then an open-vented boiler can be the best solution.
Frequently Asked Questions
It’s called an open vent system because there’s an open vent pipe. And this serves as a safety device. This pipe releases excess pressure if the system overheats.
If you have multiple bathrooms and want a steady supply of hot water, then an open-vented boiler is perfect. It’s perfect for big households and homes with older plumbing.
The open vent pipe keeps the pressure safe in the system. It lets air and steam out, stopping pressure from building up and keeping things running smoothly.
