A system boiler works together with a hot water cylinder to provide central heating and hot water to our homes. The boiler heats water directly from the mains to warm up our radiators, and fills the cylinder with boiling water that’s used for our sinks, showers and more.

Due to the use of condensing technology, system boilers are very efficient. They can achieve up to 90% efficiency in ideal conditions. Taps and showers receive immediate hot water at the same pressure. As a result, they can also improve water consumption in your home.

The answer is yes, but only if the hot water in the cylinder runs out. Since the system boiler relies on a stored supply of hot water, if you use up all the water in the cylinder (for example, after several long showers or baths), you may have to wait for the boiler to reheat the water in the tank. The amount of time it takes to do this will depend on the size of the cylinder and the power of the boiler.

Hot water isn’t always instant in busier times

Once you use all the stored hot water in your cylinder, you have to wait for some time to be able to use hot water again. Always buy a cylinder with the capacity to meet your hot water demands and needs.

Needs lots of space

Regular boilers need space for the water tank and the hot water cylinder. That’s why it’s not a good choice for smaller homes that don’t have much space. For smaller homes, a combi boiler is more suitable.

Installation can be costly

Because there are many parts to be installed around the house, a new boiler installation can be pricy. Aside from being expensive it can also take a lot of time.

To get what you exactly need, you should take a look at the pros and cons of regular boilers. There are a lot of things to think of when it comes to choosing the most suitable boiler for you.

It is all pretty simple. Basically, a regular boiler will take water from the tank to provide heating. It is important to place your tank as high as possible to have a better water flow in all the system.

A heat exchanger warms up the cold water once you turn on the hot tap or switch on the heating. After that the hot water moves to the hot water storage cylinder where it is kept and circulated. Then valves will direct hot water to the heating system or the taps and outlets.

Cold water runs through the combi boilers directly from the main water source. In order to produce heat, the gas fuel is burned. The heat is then transformed from the combustion chamber to the water through a heat exchanger.

Your thermostat would know when the temperatures drop in your house. Subsequently, it will send a signal to the combi boiler which would fire up and heat your home.

The minute the required heat is reached, your combi boiler would decrease the produced heat and keep the status quo. As a result, it will reduce your energy waste as well as keep your house warm.

A Combi boiler directs hot water to any outlet you are using such as a hot tap, a shower or a bath. When you turn off the tap, the central heating duties will be back in action.

Keep in mind that your Combi boiler directs hot water to the water outlets or the central heating, but not both at the same time.

Combi Boilers take water directly from the mains water supply in your home. To provide an appropriate water flow, they rely on the pressure coming from the mains.

So if the pressure from the mains is not strong enough, a combi boiler is not, therefore, suitable for your home.

A combi Boiler comes with two outputs; one for how water and the other is for home heating. Hot water for central heating takes less effort than on-demand hot water. That’s why it’s crucial to choose a boiler that corresponds with your hot water demands.

Another key point is that if you live in large home with many bathrooms, then a system boiler is what you need.

When we talk about boiler size, we do not mean its dimensions, but rather its power output.

The unit of measurement, used for Combi Boilers, is the kilowatt (kW). To clarify, the bigger the kilowatts, the greater the capacity of the boiler to match your demands for hot water and central heating.

We advise that you get a small (low power) combi boiler if you have a small home with only one bathroom.

On the other hand, you will need a much bigger boiler if you live in larger property with more than one bathroom.

Here’s what you need to know about Minimum kW Size:

When it comes to relying on a hot water storage cylinder, then both systems are very similar. Both of them keep a store of hot water ready for your use. However, the main difference is that a system boiler draws water directly from the mains. While, a regular boiler will take its water supply from a tank in the attic. In short, with the system boiler you do not need a cold water tank high up in the attic.

1. The Boiler Itself

A system boiler, also known as a sealed system boiler, is a highly efficient heating system. It is typically installed in the home to provide both central heating and hot water. The system boiler is connected directly to the central heating system and uses water from the mains supply.

2. The Hot Water Cylinder

Unlike a combi boiler that heats water directly when needed, a system boiler heats water and stores it in a hot water cylinder (or tank). This tank holds a reservoir of hot water for immediate use, making system boilers ideal for homes with higher hot water demands (like larger families or multi-bathroom households). The water is stored at a set temperature and is ready to be used at any time.

3. The Heating Process

Here’s how the heating process works:

• Water Supply: Cold water from the mains supply flows into the system boiler.
• Heating: The system boiler heats the water using either gas or electricity. It then pumps the hot water into the hot water cylinder.
• Hot Water Storage: The hot water is stored in the cylinder until it’s required, typically at a temperature of around 60-65°C.

The boiler continues to operate and maintain the water temperature in the cylinder, ensuring hot water is readily available when needed.

4. The Distribution of Heat

When you turn on the hot tap or shower, the system boiler sends hot water from the cylinder through the pipes and into your taps or appliances. This hot water flows instantly, meaning you don’t have to wait for it to heat up, as it’s already stored and ready to go.

At the same time, if the central heating is on, the system boiler also heats the water circulating through the radiators, keeping your home warm.

5. Sealed System

A key feature of system boilers is that they are part of a sealed system. This means there’s no need for a cold water tank (usually located in the attic) or an expansion tank. The system is sealed to maintain the pressure of the water in the system, which helps ensure consistent heating and hot water. The system is pressurized, and an automatic pressure release valve ensures it doesn’t get too high or low.

6. Pressure & Expansion

The sealed nature of the system boiler means there’s no need for venting. Instead, the system operates under a set pressure, which is maintained by a pressure vessel or an expansion vessel. The expansion vessel prevents any issues related to thermal expansion and ensures that the pressure is constant.

7. The Role of the Pump

The pump within the system boiler ensures that water is circulated throughout the heating system and hot water cylinder. This pump ensures that both heating and hot water are delivered efficiently and consistently throughout the system.

8. Efficiency and Hot Water Demand

Because the system boiler stores hot water, it is especially beneficial for larger homes with a high demand for hot water. The boiler can provide multiple outlets of hot water simultaneously, such as multiple showers, taps, and even appliances like washing machines. However, it’s important to note that if the stored water is used up, you may need to wait for it to heat back up.

There are many things to consider but one of the most crucial points is how much space do you need for a system boiler. In general, a system boiler is larger than a regular boiler so you need to make sure that you have sufficient space. What makes a system boiler bigger is the fact that it has a pump and an expansion tank. It’s worth mentioning that the additional parts would be covered by the manufacturer warranty. An airing cupboard is where the hot water cylinder most likely to be installed.

System boilers are perfect for homes with limited space because they do not need a header tank.

Without a doubt, you will get the same quality for your boiler as if you have paid for it in cash. This is something you shouldn’t worry about in the first place.

How you choose to pay for your new boiler has nothing to do with the quality of the service and the boiler.

Needless to say that you will receive the same warranty protection for the same period and quality regardless of the brand you go with. This includes the Alpha boiler, the Worcester Bosch boiler or the Viessmann boiler.

There are certain conditions that must be met before you apply for a loan with Duologi:

1. Be 18 years or over at the date of the application. Back to contents
2. Be no older than 75 years at the end of the loan term.
3. Be a UK resident.
4. Have 3 years of UK address history.
5. Have an annual income of at least £10,000.
6. Have a valid personal phone number and e-mail address.
7. Have a good credit history with no late payments, county court judgements (CCJs), debt relief orders, individual voluntary arrangement (IVA) or bankruptcies.

Of course, it does. The cost of the installation can be included in your monthly plan.

In other words, you don’t have to worry about financing the installation cost. We will remove your old boiler, get you a new one and install it. And all the installation fees will be part of your monthly payment plan.

Having a bad credit history will not necessarily disqualify you from getting a finance plan. Pass rates for boilers on finance are high if you don’t have any recent CCJs or IVAs in the last 5 years.

Sub-prime lenders often help those with poor credit history. But they would charge a much higher APR % rate due to the risks involved.

*Offered subject to status and successful credit assessment. Terms and conditions apply.

What is a credit check?

• A credit search, otherwise known as a credit check, is when a company reviews your credit report.  This is to see how well you’ve managed money or credit in the past.

• A credit check shows details about your finances, such as your existing debts and credit available to you. It can also show any financial links you have with other people.

• A credit check will also show court records.  This can include bankruptcies, payment defaults, County Court Judgements (CCJs) and Individual Voluntary Arrangements (IVAs).

• Lenders use credit checks to help them decide whether to accept you for their credit products.

* information collected from our finance provider Duologi.