An engineer came round and replaced the thermostatic valve on one of the radiators during an annual boiler service. It seems to be a Drayton TRV4. However the valve does not seem to work too well. The radiator seems to be either really hot or completely off, nothing in between.
Upon closer inspection I'm think that only the trv head has been changed without changing the trv body. I have attached a pic as reference.
I always thought that the body of the Drayton TRV4's were plastic around the pin. Also there does not seems to be the Drayton logo and the side of the body.
Would much appreciate it if someone could confirm whether or not the trv body in the pic is the Drayton TRV4 or not.