When people start researching different heating system types, they usually come across two terms quite quickly: open vented heating system and sealed heating system. If you’re a homeowner in London planning a boiler replacement or upgrading your central heating system, understanding the difference between these two setups can help you make a much better decision.
The funny thing is, many homeowners live with one of these systems for years without actually knowing which one they have. It only becomes important when a boiler breaks down, radiators stop heating properly, or a heating engineer starts talking about system upgrades.
So let’s keep it simple.
Both systems heat your home and provide hot water. The main difference is how they manage water pressure and expansion.
What Is an Open Vented Heating System?
An open vented heating system is the traditional heating setup found in many older London homes. It uses a feed and expansion tank, usually located in the loft, to manage the water inside the system.
When the boiler heats water, that water expands. Rather than building up pressure within the pipework, the excess water can move into the loft tank. This keeps everything operating safely.
Because the system is connected to the atmosphere through the tank, it’s often referred to as open vent central heating.
If you own a Victorian, Edwardian, or older terraced property in London, there’s a good chance you either have one now or had one at some point.
Advantages of an Open Vented Heating System
There are still several reasons why homeowners choose to keep these systems.
Works well with older properties
Many older homes were originally designed around open vented systems. The pipework and overall layout often suit this setup perfectly.
Less dependent on mains water pressure
Low water pressure can cause problems for certain heating systems. An open vented system generally handles these situations better.
Easy for engineers to repair
Since these systems have been around for decades, most heating engineers know them inside out.
Reliable technology
Sometimes older systems survive because they simply work. That’s certainly true here.
Disadvantages of an Open Vented Heating System
Of course, there are some downsides.
The biggest issue is air.
Because the system is open to the atmosphere, oxygen can enter the water. Over time this can lead to internal corrosion and sludge build-up.
Other disadvantages include:
- More maintenance requirements
- Potential freezing of loft tanks during very cold weather
- Greater risk of contamination
- Reduced energy efficiency
- Additional space needed for the loft tank
These aren’t deal breakers, but they’re worth considering.
What Is a Sealed Heating System?
A sealed heating system is a more modern approach to heating.
Unlike open vented systems, it does not use a feed and expansion tank in the loft. Instead, the entire system is enclosed and pressurised.
An expansion vessel is used to absorb changes in water volume as temperatures rise and fall.
Everything stays contained within the pipework.
No open tank. No exposure to outside air.
That’s one of the reasons why sealed systems have become increasingly popular across London in recent years.
Benefits of a Sealed Heating System
Many homeowners choose a sealed heating system because of its efficiency and convenience.
Lower corrosion risk
Since air cannot easily enter the system, corrosion occurs far less frequently.
Improved efficiency
Cleaner water circulation and reduced heat loss often help improve performance.
No loft tank required
This frees up valuable storage space, something many London homeowners appreciate.
Better radiator performance
Pressurised systems often distribute heat more evenly throughout the property.
Less maintenance
Generally speaking, sealed systems require less ongoing attention than open vented systems.
Potential Drawbacks of a Sealed Heating System
No heating system is perfect.
A few disadvantages include:
Pressure monitoring
The system pressure needs occasional checks. If pressure drops too low, performance may be affected.
Installation costs
Converting from an open vented heating system to a sealed system may require additional work.
Reliance on mains pressure
Properties with poor mains water pressure may need further assessment before installation.
That said, many modern homes are perfectly suited to sealed systems.
Open Vented vs Sealed Heating System: Which Is Better?
This is probably the question most homeowners ask.
The answer isn’t always straightforward.
An open vent central heating system can be an excellent option for older London homes with existing pipework and lower water pressure. They’re dependable and familiar.
A sealed heating system, on the other hand, often provides better efficiency, cleaner operation, and lower maintenance requirements.
For newer properties, sealed systems are usually the preferred choice.
For older properties, it depends on the condition of the existing system and the homeowner’s priorities.
A heating engineer can assess your property and recommend the best option based on your specific circumstances.
Why Heating System Choice Matters
Your heating system affects more than just comfort.
The type of system installed can influence:
- Energy bills
- Maintenance costs
- Boiler lifespan
- Radiator performance
- Future repair expenses
That’s why it’s worth taking the time to understand the different heating system types before making any major decisions.
A little knowledge now can save a lot of money later.
How to Stop a Tap from Dripping
While a dripping tap might not seem to be connected to your central heating system, it’s another plumbing problem that many homeowners encounter. In most instances, the cause is quite simple. When a washer is worn, a cartridge is damaged or a valve is faulty, water can still flow after the tap has been turned off.
To fix a dripping tap:
- Turn off the water supply.
- Remove the tap handle.
- Inspect the washer or cartridge.
- Replace any damaged components.
- Reassemble the tap and test it.
If the leak persists, it may require expert help, particularly when using modern mixer taps, which have more intricate internal mechanisms.
Open Vented vs Sealed Heating System: Key Differences
When comparing these two heating system types, several distinctions stand out.
| Feature | Open Vented Heating System | Sealed Heating System |
|---|---|---|
| Loft Tank Required | Yes | No |
| System Pressure | Low | Pressurised |
| Exposure to Air | Yes | No |
| Corrosion Risk | Higher | Lower |
| Space Required | More | Less |
| Energy Efficiency | Lower | Higher |
| Maintenance | More Frequent | Less Frequent |
Why Homeowners in London Choose Plumr
In any of these scenarios, it is important to get the right heating engineer as you will be upgrading an existing central heating system, replacing the heating boiler or considering between an open vented heating system and a sealed heating system.
Plumr are Best for heating & plumbing in London. The skilled technicians, clear pricing, and proven excellence in workmanship make Plumr the ideal choice for homeowners seeking to maintain efficient heating systems all year.
From boiler installations to full heating upgrades, the team provides expert advice tailored to your property’s needs.
FAQs
What is an open vented heating system?
An open vented heating system has a feed and expansion tank (usually in the loft) to control water levels and allow for expansion when the heating is on.
Is a sealed heating system more efficient?
Yes, in most cases. A more efficient overall performance is achieved due to less heat loss and corrosion in a sealed heating system.
Can I convert an open vented heating system into a sealed system?
However, many properties can be converted, the suitability of which will depend on the condition of the pipework, the boiler and water pressure.
Which heating system is best for homes in London?
There isn’t a universal solution. New houses may have their pipes sealed and while older houses in London may still be running on an open vent system they can give good service. A seasoned heating engineer will be able to suggest the best option.
