I'm new to the forum so sorry if this has been covered before - I'm replacing an old ACL with a Danfoss and I'm not quite sure about the wiring. Red to L, Blue to N then what goes to 2 and 3? Thanks in advance.
Hi Clint. Your old ACL stat is almost certainly as follows: 1 RED is LIVE 2 YELLOW is SWITCHED LIVE 4 BLUE is NEUTRAL (confirm it's '4') Which means your new 'stat's connections will be as follows: L - takes the RED LIVE N - takes the BLUE NEUTRAL 2 - the 'ON' takes the YELLOW According to this: http://assistyou.danfoss.co.uk/PCMPDF/44035v01.pdf the LIVE is wired internally to the switching part so that '2' (the 'ON') becomes live whenever the stat calls for heat, so no link is needed from the L to '1' as would usually be required. I don't get your last photo - which stat is that for? The new Danfoss? That does show a terminal '1' so if you find that the stat doesn't work (ie it does light up and show a display but doesn't actually switch on the boiler) then you'll likely need to fit a wire link (red sleeved) between the L and '1'. Only proceed with this if what I've said makes sense... And turn the power off fully.
Speaking as a novice - I haven't had to understand an electrical circuit since my schooldays in the 60s - and I'm not doubting your advice for a minute but I'd like to understand the diagram please. To me it looks like terminal 2 doesn't go anywhere so should be the earth, but 3 looks like it should have a wire connected because it links to the rest of the circuit. Help me understand please!
The new one won’t need an earth because it’s double insulated. Lots of electronics are like this these days. Terminal 3 does nothing with your current set up. Terminal 2 is called ON because when the stat is calling for heat power goes from the Live terminal to terminal 2. From terminal 2 the power then goes to either the zone valve or boiler. If you put the earth into terminal 2 it will trip the electrics. If an earth is required on anything it will be clearly marked and have its own terminal.
In your first photo on the white sticker there is a square inside a square. This means double insulated so no earth required
As Mike says. See the wiring diagram, Clint - you have a N and L supplying the new stat and if you look you'll see these go to 'electronics'? The 'electronics' is your stat, the bits that make it work. Now look at the L wire that goes to the 'top' of the electronics - you'll also see that branch off to the right until it goes to a 'switch' (do you recognise a switch symbol?). That switch has a 'pole' which swings two ways (ooh-er), one way to the '3' and t'other to the '2' - yes? So in one position you'll find that Term 3 becomes 'live' and t'other way it's '2'. When you now connect your yellow wire to '2', it'll become 'live' when the stat switch swings to 'ON' - which is what you want. Does your stat have a metal back box sunk in to the wall? If so, you'll likely find an earth terminal in there to terminate your green/yellow earth wire in. If you don't, you'll instead need to make sure that there's no way that bare earth wire will touch any other terminals - either use a screw terminal, or you should be ok by folding up the bare wire and then slipping the Y/G sleeving fully over it to fully cover it, and then fold/tuck it safely away behind the stat's plate.
One final question Mike, re the DIL switch settings - for a basic set up when the boiler fires when below a temp and goes off when that temp is reached, should I use both 1 and 3 or is just 3 sufficient?