Yes. All radiators should be balanced to ensure the central heating system is energy efficient and does not encounter any problems. The reason for this is that even a single unbalanced radiator can have a significant impact on how the system works as a whole, especially if this radiator is located close to the boiler. In practice, unbalanced radiators have 4 to 5 times higher water flows than necessary. If a radiator is never used, leaving it out will not have a negative effect on the balancing process.