Honeywell Y87RF upgrading from Sunvic TXL2000

19 Oct 2015
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United Kingdom

currently have a Sunvic TLX2000 series stat which i've been informed does not have a permanent live. Honeywell BDR91 requires a permanent live.

Is it possible to get a permanent(ish) live if the old programmer behind is placed on cont? I'm just in place upgrading the old stat to was hoping to work with the wiring already in the wall rather than having to trunk in a live and neutral from the boiler fused spur.

I know if the programmer is turned off then the live to the box will be off and the heating will be affected.

Honeywell have the below pic in the wiring guide.


I wonder if the incomingL could be the cont from the programmer?

Many Thanks



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You don't say how many wires come into the existing thermostat installation. Is it three?

Hopefully you have Live, Switched Live, and Neutral. In which case the Live likely comes from the programmer and, as you say, it can easily be made permanently Live.
Thanks for the response. Current Stat setup is below. nothing into Off, only wires in Neut, Com, and On.


Com comes from the programmer and 1 out to the zone valve.

If I put what is currently Com into L, link L to A (per the Honeywell wiring diag.), On into B and Neut into N then I'll get a permanent live by keeping the current programmer on cont if my thinking is correct?


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Just a quick update. I performed the installation as per the above and all seems to be well for now. Turning the Switch live into a permanent live by keeping the old programmer on cont seems to be a decent workaround for the time being. Love the remote capabilities, can finally keep an eye on how much the wife turns the heating up during the day!

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