Evohome & BDR91 issue

[Jamesw6810]

Hi - first post so be gentle

I have had evohome for 2years ish, trouble free and it’s a great system. However...

Yesterday my wife noticed that the controller was showing temps as per schedule as normal but no rads on.

Since then I’ve unbound and rebound the BDR91, communicates no issues, triggers the BDR on and off on request. The problem is that when prompted the BDR91 does not fire the boiler, this started as of yesterday on my second schedule, the house was warm as normal in the morning but then nothing

The boiler, Worcester combi, fires and heats manually but not when requested to by evohome

Any ideas, can’t see any specific issue here on forums or google. I’ve called Honeywell who said “as it’s communicating with the BDR then we can’t help” :/

Thanks in advance

[dty]

Is the BDR controlling the boiler directly, or is it controlling a zone valve?

If it's controlling the boiler, it could be there's a problem with the wiring, although it seems unlikely.

If it's controlling the valve, and then the valve is controlling the boiler via the orange wire and the microswitch, then I'd guess the microswitch and/or the valve has given up. Do you hear the valve open when you turn the BDR on with the push button on the front?

[Jamesw6810]

Looks like the BDR is connected direct to the boiler...?

If I Turn the BDR on manually and the boiler at the on position nothing happens. Green light is solid on BDR

Press the timer wheel down (at the correct time obviously) whilst boiler @ the on position, boiler fires up and heats whole house

Evohome still works and shuts on/off each TRV when scheduled

[Jamesw6810]

If I press the BDR button when boiler is in the on position (no timer) there is no noise or action at all, I can hear the click on the BDR.

[dty]

I'm afraid I don't know what a timer wheel is. You shouldn't be needing to mess with switches on the boiler to get it to fire up.

[Jamesw6810]

My explanation of timer wheel is the old school push in timers - where you would manually set by clicking a time you wanted heating on/off

[paulockenden]

What's your system configuration? Combi / S-Plan / Y-Plan ?

(Do you have any two or three way valves) ?

P.

[Jamesw6810]

Combi

Not sure on the valves, definitely not an expert in this area

[paulockenden]

Not an expert either, but I think with a combi system it won't be the microswitch on the back of a 2 or 3 port valve, as @dty suggested.

Unless you want to start checking voltages with a multi-meter I'd suggest that your best course of action is to call back whoever installed the system for you. With any luck you'll be able to combine it with an annual boiler service and save on the call-out costs!

[Jamesw6810]

Thanks - boiler does work perfectly on timer but not when just turned on or via evohome..

Evohome works perfectly communicating with the BDR & HR92s, strange

[Jamesw6810]

Is it possible the BDR91 has gone caput? Receives signal but then clicks and does nothing...

[paulockenden]

Which suggests that the BDR91 isn't talking to the boiler. Could be a faulty BDR91, could be something in the boiler, or could be a slightly dodgy connection which has come loose.

[Jamesw6810]

Thanks - i have a new BDR91 arriving today so ill swap the faceplate over, re bind and see from there - if not then its time to get a man in!


One last question for the sake of learning:

When the BDR receives the signal to heat, what does it then do - as in does it activate a switch in the boiler, thermostat etc

Be useful to learn this part if the faceplate swap does nothing

Cheers

[paulockenden]

The BDR91 is effectively a switch. In most configurations like yours it's effectively mimicking the behaviour of a room thermostat, so opening/closing a switch as boiler demand is needed.

With older boilers this switching is often done at 240V (mains voltage). Whereas with newer boilers it'll sometimes just be low voltage (signal) type switching. As the BDR91 provides volt-free contacts it's happy in both situations.

[Jamesw6810]

So in theory, either the BDR is not opening the switch through its own internal circuitry or the switch (whatever that is) it is trying to open is broken?