Hardwired vs Wireless programmer

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Hi all

Hope someone can give me some advice. We have a hardwired Honeywell ST699 24hr programmer in the airing cupboard. This controls the on/off times of the water/heating.

When we had the bolier replaced, plumber kept the Honeywell controls and also installed a Siemens wireless RDJ10RF temperature thermostat in the hallway.

What I do not understand is that the Siemens controller has on/off times that can be user set. Won't these timings conflict with the timings on the Honeywell controls? eg Honeywell says heating on 5am / off 9am, Siemens says on 6am / off 10am; which one will dominate?

What is the correct way to set the controls on both devices so that one becomes the "master" ?
 
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It all depends on how they are wired.
Generally duplicated controllers will be wired in parallel so that if either is ON then system will run.
 
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Generally duplicated controllers will be wired in parallel so that if either is ON then system will run.
Never heard of wiring a programmable stat in parallel with a programmer!

The Siemens wireless programmable stat replaces the heating side of the ST699 as well as any existing stat and there are two ways of wiring it.

Both assume that the prog stat uses the same wires as the old stat

1. Set the ST699 CH to permanently on;
2. Alter the wiring at the ST699 so the Siemens is fed directly from the Live terminal.

Option 2 is better is it negates any possibility of someone fiddling with the ST699 and stopping the Siemens working.
 
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Thanks. Option 1 sounds like the quickest fix for a novice.

But let's say the temp on Siemens controller is set to come on for a short time in morning and afternoon, won't the fact that the ST699 is set to ON override the timings and mean the heating is on continously?

So you are saying it doesn't matter, the Siemens will take precedent? I hope so! Wouldn't want heating ON all the time.

Cheers mate
 
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Your old stat (if there was one) would have turned the heating off - stopped calling for heat - when it reached your required temperature, even though the programmer was still 'on'.
Same difference now, just a more comprehensive thermostat in as much as it has temperature AND time settings.
 
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Thanks. Option 1 sounds like the quickest fix for a novice.
Option 2 just requires a wire to be moved from terminal 3 of the ST699 to terminal L

But let's say the temp on Siemens controller is set to come on for a short time in morning and afternoon, won't the fact that the ST699 is set to ON override the timings and mean the heating is on continuously?
No; the output from the ST699 becomes the input to the Siemens. This needs to be a permanent input, which is why option 2 is better than option 1. The time/temperature settings of the Siemens determine whether this is then switched to the boiler.
 

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