Hi, i have a Heatmiser DT (non-programmable) digital thermostat. My system runs as a 3 wire set up + earth. The new digital stat has 4 connections L,N,A1 & A2. L & N I am OK with but when i connect the yellow(switched live) to A1 or A2 the heating doesnt come on. I use an ACL timer always on and use the stat to turn heating on/off. I assume i need a live to A1 or A2 as its digital it uses L to power itself. If I do need a live to A1 or A2, whch one is live and which switched live? Can i run a short length from L to A1 or A2 to make this live? or am I completely wrong, any help greatly appreciated.....thanks
There are three common ways to wire central heating S, Y and C. If you know which you are using then we can help a little. There are others as well. The Y seems most popular with a mid position change over valve. With some systems you can't turn the hot water off on the programmer and as a result many programmers have switches and turn screws to change between 16 and I think 11 programs.
We also have volt free and non volt free versions of programmers, and thermostats.
As you can see loads of options and I assume you can't find manufactures instructions or you would not post this.
Can you describe your system with a few more details.