Honeywell BDR91 Fault / Wiring Advice

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I'm attempting to replace a very old traditional thermostat with a Honeywell BDR91 (linked to a Honeywell Y87RF2024 wireless thermostat). The wiring to the current thermostat is very simple - Neutral, Live and a "Switched" Live feed to the boiler, and I'm sure which wire is which on the existing thermostat.

On the BDR91 I've connected the Neutral to Neutral, Live to the "left" Live terminal of the BDR91 and "Switched" Live to the "B" terminal of the BDR91, and also put a link in from the "right" Live terminal to the "A" terminal of the BDR91 - exactly as per the wiring diagram (or at least how I read it).

When I turn the power back on the LED's on the BDR91 light up (so it has power) and it will respond to the wireless thermostat linked to it (and you can hear the relay respond) - but it won't power the boiler up. I'm assuming the "switched" Live feed isn't becoming live.

I can only assume the BDR91 unit is faulty (even though it's brand new) - but my confusion is that even if I link the "A" terminal to the "B" terminal there is still no power to the boiler. If I link the Live feed to the "switched" Live outside of the BDR91 using a terminal block all is fine, and the boiler powers up.

Can anyone suggest what I may be doing wrong ? or why even if the BDR91 isn't switching properly linking the "A" to "B" terminal still doesn't power the boiler.
 
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The second L terminal is only linked to the first L terminal when the PCB is clipped into place.

If you are using a programmer with this thermostat you need to wire the receiver to a permanent supply with the a terminal fed from the programmer CH output and the b terminal supplying the valve/boiler SW L.

Edit: Ignore that last part, I see this is a time programmable thermostat so the programmer is not required.
 
You have to link the two "L"s together , they are not linked internally.
 
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The last one I did wouldent work until I put a link in (n)
 
Perhaps they changed the PCB design for the newer stats but didn't update the wiring base. The 2 line terminals were designed for simple installation, with most installs having 1 wire per terminal. This is good as the terminals are rather small.
 
Hi - thanks for the quick replies.

Boiler is a Potterton NetaHeat 10-16.

Yes I've had the front cover clipped on when powered up - I assume that's what you mean by having the PCB clipped into place ?

Yes I have a Programmer is use too, but the existing cable is in the wall so hard to tell where it comes from / goes to. I assume if the LED lights "green" though it must have a feed to it ? (and at the time of fitting the Programmer would have been on).
 
Seconded, BDR91s have always had the two L pins linked.
 
It showed the L,s linked in the instructions but no power going to A when linked to the right hand L , I checked the pins were in place and it worked when I linked the two L,s together. strange but true.
 
Having a few probs with bdrs at the moment, so nothing would surprise me tbh.
 
Yes I've had the front cover clipped on when powered up - I assume that's what you mean by having the PCB clipped into place ?
Yes.
Yes I have a Programmer is use too, but the existing cable is in the wall so hard to tell where it comes from / goes to.
If you don't want to find where the cable goes, CH on the programmer needs to be set to always on.
I assume if the LED lights "green" though it must have a feed to it ?
Yes, if the green light is on, the relay should be on too. The green light goes out when the thermostat is no longer calling for heat. Pressing the grey button will manually turn it on and off for testing, but the receiver will revert back to whatever the thermostat tells it after a minute or so.

Try adding a link between the 2 L terminals as suggested above, it shouldn't be needed but is worth a try, especially as you hear the relay clicking.

If this thermostat has been wired up incorrectly it is possible it has been damaged.
(and at the time of fitting the Programmer would have been on).
Yes. However you must not use the existing programmer to control the times of the central heating with the way you currently have it wired, or it will not work properly. You need to alter the existing wiring, or set the CH to always on, and program the heating times into the new thermostat.
 

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