DIY Doctor UK DIY Forums

I am attempting to change a LAP mechanical timer - I believe the model number to be TM1H24-XD - for a Drayton LP111. The timer controls the heating side of a combi boiler.

I am having trouble with the wiring connections. The existing wiring has two cables from the boiler to the timer, one has 3 wires (L,N,E) which connects to the 'IN' side and the other has only one wire (L) which is connected to the 'OUT' side, the remaining cores of this cable have been cut short.



My question is, how would thes wires be connected to the Drayton unit, which has 6 terminals. Left to right N,L,1,2,3,4. I believe terminal 4 is a spare.

My thoughts are that the feed from the mains will connect to N,L plus earth. The boiler cable with 3 cores will also connect to N,L and earth. Looking at the wiring diagram provided by Drayton I need then to provide a jumper from L to Terminal 1(common). The problem is which terminal does the single core from the second boiler cable connect to?

Without seeing a copy of the wiring diagram you have it is only possible to speculate.
I would connect the single wire to the terminal marked NO.

(That is Normally Open, not the opposite of yes)

Thanks Mr White.I have uploaded a three attachments that I am hoping will help

Thank you so much for taking the time to help me out.

Karl

According to the diagram, the single wire you have should go to the terminal they marked it as "ON / call for heat" Terminal 3

Thanks Mr White thats excellent. I would still need to provide the jumper to T1 I am guessing as per instructions.

Thanks again

You are correct, you would still need a link from live to T1.

If it helps you, what you have is an electric switch but nothing to actually switch. By adding the link from Live to T1 you are providing something to switch (The live) and the other single wire (T3) is where it will go to when the switch is operated.

Thanks Mr White. All connected up and working so thanks for your excellent help.

kind regards

Glad to be of service.