Can I Change to a Combi Boiler? - heatingsystemwiki.com

Yes, you can change to a combi boiler by removing the old hot water cylinder, upgrading the gas run, and installing a new combi boiler. This process involves several steps, including draining the existing central heating system, removing the old boiler and water storage tanks, and configuring the new thermostat controls.

Benefits of Switching to a Combi Boiler

Efficiency and Cost Savings: Combi boilers provide hot water on demand, which means less energy is used to heat water, leading to cost savings and a more environmentally friendly option. Combi boilers can achieve up to 94% efficiency, compared to 70-85% for traditional boilers, resulting in significant energy savings of up to 35% on your heating and hot water bills.
Space-Saving: Combi boilers are more compact and can fit into smaller spaces, making them ideal for homes with limited space. The average combi boiler measures around 700mm x 400mm x 300mm, compared to a traditional boiler and hot water cylinder setup, which can take up significantly more floor space.
Easier Repair: Spare parts for modern combi boilers are easier to source, making repairs simpler and quicker. Combi boilers have fewer components than traditional boiler systems, reducing the complexity of maintenance and troubleshooting.
Instant Hot Water: Combi boilers provide hot water on demand, eliminating the need for a separate hot water storage tank. This means you can enjoy instant hot water without having to wait for the tank to heat up, improving the overall convenience and user experience.
Reduced Maintenance: Combi boilers have fewer moving parts and require less maintenance compared to traditional boiler systems. This can lead to lower long-term maintenance costs and a longer lifespan for the boiler.

Technical Specifications

Can I Change to a Combi Boiler

Hot Water Flow Rate: Combi boilers have varying hot water flow rates, measured in litres per minute (LPM). This rate indicates how quickly the boiler can heat water. For example, a 24kW combi boiler typically has a hot water flow rate of 9.9 LPM, while a 30kW combi boiler can provide up to 12.3 LPM. The higher the flow rate, the more simultaneous hot water usage the boiler can support.
System Conversion: The process of changing from a traditional boiler to a combi boiler involves removing the old boiler, water storage tanks, and upgrading the gas run. This typically takes around 2 days to complete, depending on the complexity of the job. The installer will need to drain the existing central heating system, disconnect the old boiler and tanks, and then configure the new combi boiler and thermostat controls.
Boiler Capacity: Combi boilers come in different capacities, typically ranging from 24kW to 40kW, to suit various home sizes. A 24kW combi boiler is generally suitable for a small to medium-sized home with 1-2 bathrooms, while a 30kW or 35kW combi boiler may be more appropriate for larger homes with 2-3 bathrooms.
Water Pressure: Combi boilers rely on the mains water pressure to provide hot water, unlike traditional boiler systems that use a separate hot water storage tank. If the mains water pressure is low, the combi boiler may struggle to provide sufficient hot water flow, especially if multiple taps or showers are in use simultaneously.

Suitability for Larger Homes

Capacity: While combi boilers are suitable for average homes with 1-2 bathrooms, larger homes with multiple bathrooms or high hot water demands may require a system boiler or a more powerful combi boiler. This is because combi boilers have a limited capacity to heat water and provide hot water simultaneously.
Pressure and Flow Rate: Combi boilers can struggle to provide enough hot water for simultaneous use in larger homes, especially if the mains water pressure is weak. In such cases, a system boiler with a separate hot water cylinder may be a more suitable option, as it can store and deliver larger volumes of hot water.
Radiator Sizing: Larger homes may require larger radiators or additional radiators to ensure adequate heat distribution throughout the property. Combi boilers may not have the capacity to effectively heat a larger home with an undersized radiator system.
Pipework Upgrades: Changing to a combi boiler may require upgrading the existing pipework to accommodate the new system. This can be particularly challenging in older homes with complex or outdated plumbing layouts.

DIY Considerations

Expert Installation: While it is possible to change to a combi boiler yourself, it is strongly recommended to hire a Gas Safe registered engineer to ensure a safe and efficient installation. Improper installation can lead to safety hazards, such as gas leaks or carbon monoxide poisoning, as well as potential issues with the boiler’s performance and efficiency.
System Compatibility: Before undertaking a combi boiler conversion, it is essential to ensure that the new combi boiler is compatible with your existing heating system. This includes checking the compatibility of the gas supply, pipework, and any additional components, such as radiators or thermostats. Upgrading these elements may be necessary to ensure the combi boiler functions correctly.
Electrical Upgrades: Combi boilers often require a dedicated electrical supply, which may necessitate upgrading the home’s electrical system to accommodate the new boiler. This may involve installing a new fused spur or upgrading the existing electrical circuit.
Condensate Drainage: Combi boilers produce condensate, a slightly acidic liquid, which must be properly drained to prevent damage to the boiler or the surrounding environment. Ensuring the correct installation and routing of the condensate drainage system is crucial.
Ongoing Maintenance: Regular maintenance and servicing of the combi boiler are essential to maintain its efficiency and longevity. This includes annual inspections, filter cleaning, and addressing any issues that may arise promptly to prevent more significant problems.

By considering these technical specifications, suitability for larger homes, and DIY considerations, you can make an informed decision on whether changing to a combi boiler is the right choice for your home.