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Mark Downey
 
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Default central heating programmer re-wiring

my switchmaster 905 programmer has just packed in so i thought it was about
time to get a digital one ,Just come back from B&Q with a drayton tempus 7.
After taking the front off the switchmaster it revealed this layout on the
backplate

N-L-1-2-A-B-C-3-4

n-neutral
l-live
1 central heating ON
2 CH OFF
A.B,C- SPARE
3 HW ON
4 HW OFF

feeding this I had 2* 3 core cables
1st Cable - live neutral and the green cable screwed into the spare A
2nd cable - Brown into no1(CH ON) Blue into no 3(HW ON) and Green into
No4(HW OFF)

OK
the new Drayton has this layout on its backplate

N-L-1-2-3-4

N-neutral
L-live
1 HW OFF
2 CH OFF
3 HW ON
4 CH ON

so i connected the cables up as per diagram but did not know where to put
the green cable from cable 1 - and assumed it was an earth cable so i
plugged it into the earth socket . This configuration now leaves me without
a connection into no 2 (CH OFF).
I powered up the programmer and everything came on , Great I thought.Set the
time ,adjusted the timer settings and set to auto.
When the time came for the heating to come on - Nothing - No pump running or
3 port valve switching over
Also nothing comes on in manual either.

So can any of you kind people help me.

Mark