Have a ariston boiler system boiler. Drayton RTS1 room stat and a drayton Lifestyle LP112 programmer. I want to replace the RTS1 with the honeywell DT90E - I believe the system uses a neutral to switch @240 mains also in conjunction with this lifestyle timer. So do I need all 3 wires to new Honeywell or can I just use 2? The DT90E supports mains and low voltage so I just want to know wats the best method of doing of this please? PS- some posts regading this are unclear with regards to my scenario so apologies to those who have supported this issue more than once!.