Replacing Switchmaster 400 with Drayton Tempus 7

I'm replacing an old Switchmaster 400 with a Tempus 7, thought it looked easy but a couple of nagging worries.
Apologies for non industry standard terms!

On my Switchmaster 400 it says terminal 2 should have no wires attached yet it has 3, two blue and one black. One of the blue wires is attached to the neutral terminal. Are these just like this to save on boxing them off? And there's nothing in terminal 4 (CH/Off) but there's not one when i wired up my Drayton Digistat 1 so presume it doesn't need one. Terminal N has three blue wires, terminal L has 1 red wire, Terminal 1(C/H on) has one red wire, Terminal 2 see above, Terminal 3(H/W on) has one red and a yellow wire, Terminal 4(C/H off) has nothing and there are two more yellow wires boxed off. Earth is pretty self explanatory (3 of them).

So should i just wire them up on the Tempus 7 to the correct pins as per instructions just boxing off the wires in terminal 2 and the two yellow wires or should i just phone someone who knows what they're doing up. What's the worst i could do? Blow the 3 amp fuse? Or maybe not!

What do you mean by "boxing off"?

i gather you mean that you will make the ends of the cable/wires safe
best thing to do is follow the wiring guide supplied with the time clock

Sorry with boxing off i meant joined together in electrical terminals.

And as i say is it ok to follow the wiring diagram, i was just worried about the wires in terminal 2. And the blue one that went from the mentioned terminal 2 to neutral.

Thanks for the replies.

gazza67 said:

Sorry with boxing off i meant joined together in electrical terminals.

And as i say is it ok to follow the wiring diagram, i was just worried about the wires in terminal 2. And the blue one that went from the mentioned terminal 2 to neutral.

Click to expand...

Terminal 2 on the SM400 is not used. If it has been connected to the Neutral on the SM400 and other wires have been connected to T2, then it is being used as a junction point for a number of neutrals. There are no "spare terminals on the Tempus 7. From your original description it appears that there is no wiring centre as there are multiple wires going to each terminal of the SM400.

It would be sensible to install a wiring centre (junction box), cost about £10, and connect everything through that. Apart from looking more "professional" it will make fault finding easier when things go wrong. If you supply the info below about your system, I can point you to the correct wiring diagram.

What boiler do you have - make and full model no (or GC number)
Number and type of motorized valves
Which room thermostat
Which cylinder thermostat (not immersion heater stat)
Pump location

Thanks again, but would it be ok just to wire it up following the wiring instructions as they are and just join the wires on the unused terminal in a connector?

gazza67 said:

would it be ok just to wire it up following the wiring instructions as they are and just join the wires on the unused terminal in a connector?

Click to expand...

Should be OK. There will be a cable with one wire connected to the Switchmaster L terminal and the other wire to either the N or 2 terminal of the Switchmaster; this will be the supply to the Switchmaster. Connect this cable to the L and N terminals of the Tempus.

Also connect the Tempus N terminal to a connecting block with a short length of wire and then connect all the other wires from Switchmaster N and 2 terminals to the connecting block.

The other wires can be transferred to the appropriate terminal on the Tempus7. There should not be any connection to the CH OFF or HW OFF terminals.

Once again thank you sir for your quick resopnse.

All done & everything seems to be working the way it should. Thanks again everyone for input.

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