Nest Thermostat

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I have the nest 3rd gen; stat, running with a heat only boiler (Vaillant) on a Y plan system.
Cylinder stat -Honeywell L641A1039
3 way motorised valve Danfoss HSA3.

The problem I have is with the HW scheduling, I have scheduled HW twice a day 1 hr each time, ie; 0700/0800 & 1700-1800
However the HW comes on different times to the settings.
I have wired the heat link as follows,
N L.
linked 2&5 to L,
3 -white on zone valve ,
4-grey on zone valve & 1 in cylinder stat,
6 - Com on cylinder stat,
2 on cylinder stat - orange on zone valve & linked to L
The pump is wired direct to boiler.
Heating works as it should.
Your help would be appreciated
 
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CBW

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Is this how it was wired previously? Photos of Nest and wiring center would help.
 

CBW

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That is wrong , the orange is the switched live to the boiler , you have put a permanent live on it
Ahh, misread/misunderstood that, flicking between the diynot post and Nest instructions in ibooks, it should be on live to boiler (switched), thanks Ian.
 
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Thanks guys for your input , Ill double check later at the orange wire,
are you saying if the orange wire in connected to a permanent live that is why my HW is coming on randomly ?
 
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Thanks guys for your input , Ill double check later at the orange wire,
are you saying if the orange wire in connected to a permanent live that is why my HW is coming on randomly ?
It means it will never go off
 
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It means it will never go off
After checking again
bob1956 said:
should read
2 on cylinder stat -orange on zone valve & linked to L on boiler
My bad. Just to add the HW is not permanently calling for heat , it just comes on randomly at different times to how I have scheduled it .
The orange wire is not permanently live.
 

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