Tipex Posted July 10, 2011 Report Share Posted July 10, 2011 I want to replace my aging room stat for a spangly new digital one, I've bought a new one, but I'm not sure how to wire it correctly, it only requires 2 wires, whereas the old one has 3. This is the old one, and it's wires - The new one has 3 connections, labeled as NO, COM, NC, but only has wires connected to 2 of them, in the little book it says, and I quote - "The thermostat can be used with single stage heating system, inside the thermostat, three terminals which label COM, NC and NO would be found. Connect the heater to terminal COM and NO (or NC depends on type of heater), in most cases, COM and NO are used." So, having done some Googling, I guess I connect the red wire to COM, and the Yellow wire to NO, and just terminate the blue wire? What's confusing me most is the "or NC depends on type of heater" in the book, as it fails to elaborate on what type of heaters connect to what? Anyone got any ideas? Link to comment Share on other sites More sharing options...
Calm Chris Posted July 11, 2011 Report Share Posted July 11, 2011 The old ones have a neutral which isn't required on a digital stat (when wired to a boiler via a CH sys). So Com and NO will be the correct terminals. I can't read the little paper diagram on the picture, so can't say what the red, blue and white wires are. If they don't say, open up the wiring centre (junction box) that the cable goes back to. Identify the 3 wires, one will terminate on position 2 of the wiring centre, that's the neutral disconnect it and tape the end. The other 2 wires should terminate on position 4 and 5 at the wiring centre. 5 being common, 4 being NO. Link to comment Share on other sites More sharing options...
Tipex Posted July 11, 2011 Author Report Share Posted July 11, 2011 Cheers, I'll see if I can get a better pic of the diagram, as I suspect the other end of the wire will terminate in a birds nest of wires! Link to comment Share on other sites More sharing options...
Tipex Posted July 11, 2011 Author Report Share Posted July 11, 2011 Ok, here's a better pic of the wiring diagram, hope this helps, the picture seems to show the diagram better than it actually looks in real life, as it's somewhat faded with age, and probably not very well printed to start with! The yellow wire connects to terminal 2, the blue to terminal 4, and the red to terminal 6. Link to comment Share on other sites More sharing options...
Tipex Posted July 14, 2011 Author Report Share Posted July 14, 2011 Shall I just lick the wires, then connect them to the terminals depending on what flavour they are? Link to comment Share on other sites More sharing options...
burble Posted July 15, 2011 Report Share Posted July 15, 2011 The old one switches on 240v, does the new digital one also switch on 240v or does it use a 12v switching signal? Link to comment Share on other sites More sharing options...
Tipex Posted July 15, 2011 Author Report Share Posted July 15, 2011 Erm, I think it does either, will check when I get home tonight. Link to comment Share on other sites More sharing options...
Tipex Posted July 15, 2011 Author Report Share Posted July 15, 2011 It's a Horstmann DRT1 if that helps? Link to comment Share on other sites More sharing options...
Calm Chris Posted July 15, 2011 Report Share Posted July 15, 2011 Tipex, plumbers do what they want and don't always work to any rules. I hate guessing, and hate giving advice when I've not seen the whole picture. The wires should be:- Neutral - Blue Red- Live Yellow- Switched live So your stat as a 2 wire will use the red and yellow. Safely tuck the blue to one side, terminate on a dummy screw point (if the stat has one) or tape it up. Join the red and yellow together, turn the programmer to CH and the CH should fire up. Once that's tested, terminate the wires on the stat and re test by moving the temp dial down to room temp. That will turn the CH off, up the temp on the stat and the CH will fire (boiler starts, valve moves and pump kicks in). Link to comment Share on other sites More sharing options...
Tipex Posted July 15, 2011 Author Report Share Posted July 15, 2011 Thanks for the advice, I do appreciate it can be hard when you can't see the system, I was 90% sure it was those two wires, just wanted someone else to confirm it 'should' be those two as well. I'll tinker tonight! Link to comment Share on other sites More sharing options...
Calm Chris Posted July 15, 2011 Report Share Posted July 15, 2011 I'd get rid of that wall colour 1st...... Link to comment Share on other sites More sharing options...
Tipex Posted July 15, 2011 Author Report Share Posted July 15, 2011 Lol, the whole house was painted magnolia, except for the kids bedrooms, as the mrs didn't know I'd bought the house, it needed a lot of work, and I had a fixed (short) timescale in which to get all the major work done, so I could surprise her, and we could move in before she gave birth to our daughter, which actually happened a week after we moved in. So it was all painted magnolia so it looked clean and fresh and so she'd be happy, we've slowly been redecorating to how we actually want it, but not done that room yet, as I hate decorating, and she's pregnant again. So, give it another year or two, and it should be all nicely decorated, rather than magnolia! Oh, I've done it BTW, and all seems to be working correctly, thanks for the advice, it's much appreciated, just got a new programmer to fit next... Link to comment Share on other sites More sharing options...
Calm Chris Posted July 15, 2011 Report Share Posted July 15, 2011 Congratulations to you both regarding the expanding Tipex range. Programmers are easy, or would be if you post pictures of the wiring centre and the existing kit. Link to comment Share on other sites More sharing options...
Tipex Posted July 15, 2011 Author Report Share Posted July 15, 2011 Congratulations to you both regarding the expanding Tipex range.Programmers are easy, or would be if you post pictures of the wiring centre and the existing kit. I may well do that! The 'wiring centre' you speak of is what worries me most, I hope I'm wrong, but think I'm going to be looking at a veritable birds nest of wires, I shall get a 10 way JB and tidy it all up if so, but I haven't been brave enough to remove the cover and look yet! I wouldn't bother replacing the controller normally as the whole system is very old, but it works flawlessly, and we have plans for extensive building work that will include a whole new system, but that's a few years off yet, the problem is, the time clock has stopped turning with any degree of consistency, so it can be a lottery as to when we get hot water and heating, which means the hot water is permanently on, and also the heating in the winter, so it's not exactly being efficient. Link to comment Share on other sites More sharing options...
Calm Chris Posted July 16, 2011 Report Share Posted July 16, 2011 No matter what the state of "the wiring centre" they are very easy to do. The pump, the valve(s) and the control / timer all tend to have set places and set colour codes. Photograph each item and the wiring centre connections and I can walk you though any issues or potential feck up's. Link to comment Share on other sites More sharing options...
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