Nest advice with my current system

17 Nov 2007
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United Kingdom
Hi, just looking at my current setup to see if I'll buy a nest and go ahead with installing it.

I have a Potterton profile 60e boiler, Honeywell st7100 control panel and a single thermostat, hotwater tank and a 3 way valve. This is all connected to a Honeywell sundial box which I believe is wired in a Y-plan.

Is it going to be a simple task of using the wires to the current st7100 control panel to the nest heatlink

and disconnect the current thermostat wiring in the sundial box and use it from the heatlink to the nest thermostat

or is it a bit more complex, I need to remove the sundial box and link all to the heatlink? Many thanks!
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It depends. Do you want to power Nest off the Heat Link or are you plugging it in?
It depends. Do you want to power Nest off the Heat Link or are you plugging it in?

I haven't 100% decided yet, I was thinking of maybe moving it from the location of the current one. Let's go for power it for now
Ok, I've had a proper look at it now and think I've sussed it. Found a diagram of the Honeywell sundial box which makes things much easier to understand:

So does this look correct:
Live to heatlink L, 2, 5
Neutral to heatlink N
Sundial CH On to heatlink 3
Sundial HW Off to heatlink 4
Sundial HW On to heatlink 6
Disconnect thermostat wiring in sundial and use two wires for heatlink T1 & T2 to nest

The only thing I'm not sure on is do I then need to link roomstat 1 & 3 together in the sundial box as I guess if I don't do this the heating won't come on when the heatlink signals to turn on the heating
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Does it look like I am correct in the post above? Or can someone recommend somewhere else I can ask?
Hi I have the same sundial junction box and was wondering how to connect up my 2nd gen heat link? I don't know much about wiring and wanted to know what wires go where.
Thank you.

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