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Can you mix steel and aluminium radiators on a central heating system?

23 October 2023

Mixing steel and aluminium radiators on a conventional hot water heating system is possible, and provides several advantages, but it requires some technical considerations.

 

Your radiators are steel and you want to add an aluminium radiator

The majority of conventional hot water heating systems will use steel radiators. If you want to add a new designer feature radiator or two, then its definitely worth considering an aluminium radiator. The chances are you have done your research on the energy efficiency of aluminium radiators versus their steel counterparts. Here we explain what you need to know when adding an aluminium radiator to a hot water heating system which incorporates predominantly steel radiators.

 

Mixing steel and aluminium radiators in a single central heating system

While it is possible to mix steel and aluminium radiators, it's important to proceed with caution and ensure that the different radiators are integrated properly into your central heating system to ensure optimal performance, efficiency, and longevity.

 

Here are some important considerations to keep in mind:

  1. Heat Output and Sizing: The functionality of a radiator is based on the heat output required for the room it’s going to be fitted in. When mixing radiator types, it's crucial to ensure that the combined heat output of all radiators in a room meets the heating needs. This means you need to assess the BTU’s needed to heat a room, or space you’re considering adding a new designer radiator.

 

 

This is a simple process, you can use our online BTU Calculator, just add the room dimensions and it will give you the BTU’s needed to effectively heat the space. Then if there are multiple radiators, subtract the BTU output of the radiator(s) which will remain, and this leaves you with the BTU value you need for your new radiator. If you don’t know the value of the radiators in situ, don’t worry, you can still manage the heat output in the room by balancing the system.

 

  1. Balancing the System: Mixing aluminium and steel radiators means they have different heat conductivities, and this can affect how the system balances heat distribution. It’s highly likely you’ll need to adjust the flow rates to different radiators to ensure even heating throughout the house. This isn’t as scary as it sounds, as you can use TVR’s.

 

 

  1. Using Thermostatic Radiator Valves (TRVs) to balance the system: When adding a new aluminium radiator to a conventional hot water central heating system with steel radiators, you can use Thermostatic Radiator Valves (TRVs) to balance the system. It's generally a good practice to slightly over-specify the BTU (British Thermal Units) output of the new radiator. TRVs help control the heat output of individual radiators based on the room temperature. By slightly over-sizing the new radiator, you allow for more flexibility in adjusting the TRV settings without sacrificing comfort. This can make it easier to balance the system and achieve even heat distribution. provides sufficient heat to the room while maintaining a balanced and efficient heating system.

NOTE: It's important not to excessively over-specify the radiator, as this could lead to inefficiencies and higher energy consumption. The goal is to strike a balance where the radiator is adequately sized for the room's heating needs without being too large that it becomes wasteful.

 

  1. Corrosion and Water Quality: Aluminium and steel have different corrosion resistance properties. If your central heating system uses a mix of aluminium and steel radiators, it's important to use appropriate inhibitors or additives in the water to prevent corrosion and scale build-up. This can help protect both types of radiators.

 

Free Professional Advice: If you’re worried or have questions about mixing mix steel and aluminium radiators in your central heating system, then call our free helpline. Our team of radiator professionals can assess your specific setup, provide guidance on compatibility and balancing, and recommend any necessary adjustments or precautions. Call us on 01530 564 122


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