Can I get a solution for FCU with chilled water line control with TADO thermostat.
The isn't a simple answer to this - if the FCU is simply switched on / off and doesn't require regulation, then it could be controlled by the Smart Thermostat, as long as it is not switching more than 6 amps.
However, the logic for the Smart Thermostat is set up to control for heating only and not for cooling, so it would close the relay when the temperature drops below the set-point, and open it when it goes above the set-point (the opposite of what you need for cooling).
There is a way around this, as the Smart Thermostat has an NO (Normally Open) and an NC (Normally Closed) connection, but it would mean that you need to switch between NO (for the heating season) and NC (for the cooling season) manually. Additionally, this isn't supported officially, so we would not be able to give you much support if issues arise.