"The lockshield is a duplicate valve without a head, good if you decide to change ends at a later date but NO advise on how to set up for balancing!
Having arrived to do the job you find you have to "request the data sheet D34 from Drayton" if you have internet access and download it you find they then want to sell you Pre-setting keys available in packs of two, part number 07 35 162. A search showed them at £9.34!
So ok you can figure it out and bodge the adjusting with pin nosed pliers but I can't be doing with manufacturers who think everybody knows their products inside out and wants to carry around special tools that they may not need for months by which time they have got lost."
"Valves bodies are blank off apart from a small hole. As both ends take the same body the flow rate is restricted so if the radiators in question are not given priority the flow is practically non existent. Drayton's previous TRV which I've had 12 for approx 15 years have a 15mm opening in the lockshield and the TRV valve itself had only the valve with no added restriction of a small 6 mm hole (approx) drilled in the bodyopening. Money WASTED would not recommend and Drayton technical department were as helpful as chocalate fireguard. Balancing the flow was impossible."