I'd like to replace my old Central Heating/Hot Water programmer and can't work out the connections. The programmer I have is: Controller 3000 made by "Smiths Industries Environmental Controls" Type 67-040-15 240v 10W 5A switch rating Wall Plate Asssembly: 67-070-68
Pin layout: L N E 1 2 3 4 5 6 7 8 9 10
LNE is obvious Pins 2 3 4 all control the 3 port valve A wall thermo is conected between 8 and 9 A HW cylinder thermo is connected between 8 and 10 Pin 7 is live (240v)
I'd be really grateful if someone could help me out with the pin allocations or point me in the direction of a spec.
I really don't know what arrangement you have there as I have written out a circuit diagram and tried to untangle the various connections. It is possible that somebody else (maybe Roger) will be able to explain your exact setup, but I can't. I think your current programmer also incorporates a wiring centre (as it has far more terminals than I might expect) which without seeing how the connections interact it is impossible to understand.
However, if I was doing the job I would start again from first principles as follows.
Let us start from the premise that you want a new controller, and at the moment you have a fully-pumped HW and CH system, controlled by a single 3-port valve. (Known as Y-Plan). If this is the case then read on.
Your new programmer will have 6 connections on it. Live, Neutral, HW OFF, HW ON, CH OFF and CH ON.
This means that the inputs are Live and Neutral. The other 4 are outputs, HW ON, HW OFF, CH ON and CH OFF:
1) HW ON will become live when there IS DEMAND for HW (i.e. when you have set the timeswitch for HW ON)
2) HW OFF will become live when there is NO DEMAND for HW. (i.e. at all other times).
3) CH ON will become live when there IS DEMAND for CH (i.e. when you have set the timeswitch for CH ON)
4) CH OFF will become live when there is NO DEMAND for CH.
Following on from these four outputs will be two thermostats and a
3-port valve. The 3-port valve has four wires, three inputs and an output.
1) INPUT - HW Not Required
2) INPUT - CH Required.
3) INPUT - Neutral
4) OUTPUT - Boiler call for heat.
Further downstream will be a Call for Heat INPUT to the boiler. All you have to do is to connect these components up correctly with respect to the outputs from the programmer so that the Call for Heat becomes live at the correct time, and the 3-port valve is in the right position according to the demands of the programmer.
How do you do that then? Well...
First of all ascertain that your tank stat is of the changeover type which means it must have one COM input, and two outputs. One output when the switch is open (i.e. the water has reached the desired temperature) and the other when the switch is closed (i.e. the water has not yet reached the desired temperature).
1) Wire HW ON from the programmer to the COM terminal of the tank stat.
2) Wire HW OFF from the programmer to HW NOT REQUIRED of the 3-way valve.
3) Similarly wire Tank Stat Satisfied to HW NOT REQUIRED of the 3-way valve.
4) Wire Tank Stat Unsatisfied to the boiler's call for heat.
5) Wire CH ON to the COM terminal of the Room Stat.
6) Wie Room Stat Unsatisfied to the CH REQUIRED input of the 3-way valve
7) Wire Boiler Call for Heat output from 3-way valve to the boiler's call for heat.
You have then connected up all wires to all terminals apart from the Live and Neutral inputs on the programmer, and the Neutral input on the
3-way valve, and they're easy. Note that you will not have used the CH OFF output from your new controller. This is not needed for Y-Plan.
It is normal to use a wiring centre sited near the controller to facilitate these connections.
I hope this has been some help and not just caused a lot of confusion. Also you have not mentioned a pump - I presume this is integral to the boiler?
Hi Luke, Thanks a lot for your considerable effort in explaining all of this to me! Wow - this doesn't sound like a simple job! I was hoping for a response like: wire pin 2 to CH ON, etc etc ;-)
fyi: I can confirm that it is Y plan (from what i've read) the pump is external to the cylinder the two thermos both have just two connections and neither are marked
So w.r.t the thermos - what changes are there to your above instructions?
Hmm. It looks like Geoff is familiar with this particular programmer, which looks to me like it's a glorified wiring centre with timeclock built in. If we work from the assumption that the programmer cannot be repaired and a similar model cannot be sourced, you'll have to start with the first principles I described above. It's actually not too complicated once you separate out the component parts.
Your room thermostat is fine. Regarding you tank thermostat, if you do not fit a changover type then you will not be able to make the connection 3) described in my earlier post. The effect this will have is that your 3-way valve will never be able to switch to CH only when HW is demanded. I.e. if the programmer demands HW and CH at the same time, and HW is up to temperature, then the tank will continue to be heated unnecessarily. In reality, this is probably not a big deal.
However, three questions still remain.
1) Where is the boiler connected to?
2) Where is the blue (neutral) wire from the 3-way valve connected to?
3) Where is the pump connected to?
Once you've got these questions answered, you can get cracking.
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