Pros and Cons for House Renovation

Choosing the right heating system for your house renovation is a crucial decision that can greatly impact the comfort and functionality of your home. Two common options to consider are a combi boiler and a system boiler with a hot water cylinder. Each has its own pros and cons, including factors such as cost, space utilisation, and usability. Let's explore the principle differences between these two options to help you make an informed decision:

Combi Boiler:

A combi boiler, short for combination boiler, provides both hot water and central heating in one unit. Here are its pros and cons:
Pros:
1. Space-saving: Combi boilers do not require a separate hot water cylinder, saving space and potentially freeing up room for additional storage or living space.
2. Efficiency: Combi boilers heat water on demand, eliminating the need for storing hot water in a cylinder. This can result in increased energy efficiency and lower heating bills.
3. Hot water anytime: As the water is heated directly from the mains supply, you can enjoy hot water almost instantly at anytime, without having to wait for an entire cylinder to heat up. So you can have unlimited amount of hot water but only at the flow rate it can cope with.
4. Installation cost: The installation of a combi boiler is generally less complicated and time-consuming compared to a system boiler with a cylinder, which can potentially lower installation costs.
Cons:
1. Limited flow of hot water supply: Due to the absence of a separate hot water cylinder, the flow of hot water supply from a combi boiler is limited. This means that simultaneous usage of multiple hot water outlets may reduce water flow or temperature. If you envisage using multiple bathrooms simultaneously this is probably not the best option for you.
2. Pressure fluctuations: As combi boilers rely on mains pressure, water pressure fluctuations can occur, leading to variations in the performance of showers and taps. It is possible to use an accumulator tank with a combi boiler that will increase the flow and pressure going into the boiler but this might negate many of the advantages, ie you need to accommodate a large accumulator tank.
3. Incompatible with high pressure / high flow showers: Combis may not be suitable when considering powerful showers, as their water flow rate can be limited. So if you are thinking about having a rain shower or body jets, a combi boiler probably won’t cut it.

2. Intermittent temperature: If you use short burst of hot water for any reason, a combi boiler can be a little frustrating as the burner fires up and shuts off on demand. This means that it might take a few seconds for the hot water to arrive at the tap and every time your turn the tap off and on again, a small amount of cold water will enter the system creating a potentially annoying fluctuation in temperature. Some boilers have a small hot water storage tank built in which can help mitigate this problem.

System Boiler and Hot Water Cylinder:

A system boiler works in conjunction with a separate hot water cylinder to provide central heating and hot water. Here's what you need to know about its pros and cons:
Pros:
1. Greater hot water capacity: The presence of a hot water cylinder allows for a high flow of hot water supply, making it ideal for households with multiple bathrooms or high-demand hot water usage.
2. Hot water performance: With a system boiler, you can expect consistently strong water pressure and flow, ensuring an enhanced shower experience. If your main pressure is low it is possible to use an accumulator tank and pump or of course an traditional tank in the loft with a system boiler to create high flow and good pressure.
3. Compatibility with power showers: System boilers are well-suited for powerful showers, as they have a higher flow rate and can handle increased hot water demands.
Cons:
1. Space requirements: System boilers require an additional hot water cylinder, which takes up additional space in your home, potentially reducing storage or living space.
2. Installation cost: Compared to combi boilers, the installation of a system boiler and hot water cylinder is generally more complex, potentially resulting in higher installation costs.
3. Hot water delay: As the cylinder needs to heat up, there can be a delay before hot water becomes available. This is particularly noticeable if all hot water is depleted.
In summary, choosing between a combi boiler and a system boiler with a hot water cylinder for your house renovation should consider the specific needs of your household. Combi boilers are typically more space-efficient, energy-efficient, and cost-effective to install. On the other hand, a system boiler with a separate hot water cylinder offers greater hot water capacity, performance, and compatibility with power showers. Assessing factors such as household size, hot water demand, available space, and budget will help you make an informed decision that best suits your requirements.

NB A megaflo is a brand name for a mains pressured hot water cylinder compatible with a system boiler (others are available).