I assume too, that the existing thermostat is actually controlling the heating at the moment. I've seen some installations where there's a thermostat with a cable in, but it wasn't connected to anythng at the other end. My initial feeling is that a fuse went off in the junction box and that’s caused the programmer to go blank with the two lights lit to denote a replacement fuse is required? Not sure why the heating and and potentially HW stayed on though. I have considered changing my own thermostat, but mothers house had so many problems with wireless link, so not keen on wireless, at the moment using Nest Gen 3, as it sends info through the same two wires as it gets the 12 volt power, so all done with two wires boiler area to main house. But Nest Gen 3 does not connect to TRV heads, it said it did, but alas that's not true, but mainly the problem is house design, late mothers house worked fine without linking TRV's, but this house hall cools too slow. The only things that seem to show are the two lit LEDs denoting that the hot water and central heating boost are on. I’ve attached a really bad picture to show the green lights that are lit.

Looked at Tado but info was not readily available, it seems some models not for sale in UK, same with Nest USA Nest has temperature senders but not the UK model. random turning off of the display of the programmer console Drayton Lifestyle LP522 with two lights denoting HW/CH boost are on Another possibility is that the room thermostat and /or programmer have been moved at some point and the wires extended from another junction box using wires with a different colour. Read around and some say it could be a blown fuse which this turn off of the display is telling me but I don’t get why the two lights would be on?And all central heating should come from the same 230 volt supply, otherwise and UPS system to keep it running will not work. However my TRV's with this house (oil fired) have not worked anywhere near as good as with late mothers house (modulating gas) how much down to how pipework installed and how much down to on/off boiler I don't know. Unfortunately, whilst the wires have to terminate at their correct points for the heating to work, there is no fixed way of getting them there. I have seen 100's of installations over the years and I'm pretty sure no two of them have been installed exactly the same. Setting times for central heating and hot water to switch on and off can help reduce your home's energy consumption. Much depends upon the layout of the various components in your home, if the system has been modified or moved in the past, the personal preferences of the installer, and the materials they had to hand. Lots of variables really.

With the majority of installations, the thermostat is connected to the wiring centre, but not always. The programmer is usually the second most common place, generally because it is downstairs and closer to the thermostat than the wiring centre which can be upstairs in an airing cupboard. The Nest thermostat is connected to the Heat link terminals T1 & T2 (or it can be powered using a separate plug in power supply) If you are using T1 & T2 for the thermostat, the earth terminal just to their left, also needs connecting to earth. Allowing different programmes for weekdays and weekends and independent timing of each channel. LP522 provides the ability to control central heating even more efficiently. No longer do systems have to switch on as early at weekends as they do on weekdays. Finally the old thermostat needs to be decommissioned. The simplest way is to leave it in place and put both wires in the same terminal so that they are electrically connected. Another thing is that the hot water was a lot hotter than it usually was but perhaps this was because the water was left on for longer than it usually does.

LP722

I turned the boiler off overnight as I thought maybe the system had been bugged and central heating and hot water were on. Also, whilst there maybe a nomenclature in the wiring centre lid stating the suggested function of each terminal, often it is ignored. boiler turned off in case heating was left on as I can’t see if it is on the display (but could hear it working)