You should replace your thermostatic radiator valves (TRVs), or at least upgrade the TRV heads, if they are 10 or more years old.
TRVs can decline in terms of performance and accuracy over time.
To learn more about what TRVs are and why they may be beneficial, check out our guide to Thermostatic Radiator Valves.
And, if you’re considering changing yours, take a look at our comprehensive Radiator Valve Guide.