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And to answer Hengus' question - open therm bridge operates same
Thanks. This is all very useful information. Clearly, a lot of thought has gone in the design of the various components. It might be helpful - to both old and new users - if the various failsafe modes were explained in more detail in the accompanying Evohome literature.
I could find no reference to the Opentherm Bridge and Failsafe modes in my various online searches.
I've tested fail safe before but only back when I had no hot water control, so I thought I'd test it again now I'm using a 3xBDR91 S-Plan configuration.
So I set the controller to away mode (10 degrees for me) and waited 15 minutes until the pump overrun had definitely stopped. I then removed the batteries from the controller off the dock and waited...
For BDR91's the following happened:
0-50 minutes - nothing
50 minutes - the red light on all three relays started flashing.
60 minutes - the red light on all three relays went solid red and the green light on the heating zone valve relay came on and stayed on. No boiler relay yet though.
70 minutes - the green light on the boiler control relay came on and started cycling 2 minutes on per 10 minutes as expected.
The green light on the heating zone valve relay stayed on constant ever since then. This makes sense because without the controller to keep the boiler relay and heating zone valve relay in time with each other they would drift out of sync after a while and you would end up with them both running for 2 minutes but not the same two minutes... better to cycle the boiler relay and keep the heating zone valve relay on constant. I'm going to assume that in a two relay configuration it's the heating zone valve relay that cycles on and off however.
For HR92's the following happened:
0-30 minutes - nothing
30 minutes - "Syncing" appeared at the bottom.
60 minutes - "No Sync" appeared at the bottom. Also those HR92's in zones with remote temperature sensors reverted back to their internal temperature sensor at this point. The set point was still 10 degrees.
110 minutes - most of the HR92's changed to reporting "Comms" at the bottom, and both the wireless icon and an exclamation point in the top left started flashing. At this point they changed set point from 10 degrees to 20. (Not 21) A couple of straggling HR92's changed about 20 minutes later.
So it takes an hour of lost comms for a BDR91 to start cycling on and nearly 2 hours of lost comms before an HR92 changes its set point to 20 degrees.
What I did notice is that the 20% duty cycle was not enough for the rooms to warm much - they would never have got to their set points but hopefully it would have been sufficient to avoid freezing temperatures.
If you press the button on the boiler relay it changes from 20% duty cycle to staying on 100% - so if you were home and the controller failed you could do that. Pressing it again turns it off. When you turn it on or off with the button it stays that way without the controller to override it.
So anyone worrying about fail safe mode turning on your boiler unnecessarily, you would have to have pretty bad comms problems for no messages to get through for these lengths of time - and if you did, you really ought to get to the bottom of the problem as the system won't be functioning very well with such poor comms!
QED :-)
So don't worry when you go skiing.
getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own
I may be having another senior moment: they happen at my age, but aren’t the weak links here either a failure of the heating BDR or Opentherm bridge? I can see that if the Evotouch loses contact with the HR92s, BDR or Opentherm Bridge that failsafe will work. What happens if the heating BDR or bridge fails (ie; a more significant event than just a loss of comms)?
I may be having another senior moment: they happen at my age, but aren’t the weak links here either a failure of the heating BDR or Opentherm bridge? I can see that if the Evotouch loses contact with the HR92s, BDR or Opentherm Bridge that failsafe will work. What happens if the heating BDR or bridge fails (ie; a more significant event than just a loss of comms)?
Pretty hard (impossible ?) to protect against a failure of a BDR91 or OpenTherm bridge ? Fail safe is implemented in those devices so by definition if they failed you have no fail safe.
In that case you'd be relying on the frost stat in your boiler to come on if the house fell to freezing temperatures - by that time the HR92's would have opened due to their own individual frost protection.
Asking what happens if the BDR91 fails is a bit like asking what happens if my conventional digital wall thermostat fails - the boiler won't fire unless its own frost stat kicks in...
I think the chance of a BDR91 failing is a heck of a lot less than a comms failure or the controller being left off the charging dock.
Call me old-fashioned, but if I go away in the winter for more than a few days I would always turn off the water at the mains in the street and turn off the gas at the meter. That way I know that the worst that I would come back to would be a burst pipe but not a flood or a gas leak. There is no way I would trust my home to a wireless controlled battery powered heating system while I am a long way away!
And I judge the probability of an internal freeze sufficient to burst a pipe in the UK now to be very small - even in Scotland! I would rather take that risk.
Did anyone else notice some funky looking icons on the top of the zone screen on their app just before it reloaded? Opened it on my Tab S3 last night and it was still on the screen I had left it.
For a split second before it reloaded the app automatically, there was a battery strength icon, wifi signal strength icon and one other I didn't get time to make out.
Haven't been able to recreate it unfortunately. Wonder if our red bannered friends have got something in the works?
Kind Regards - Dan Robinson (Jennings Heating Ltd)
Just wanted to confirm that the app is working reliably for me too, in fact its probably working better than it ever has before - about 5 seconds to log in from scratch and no errors or intermittent behaviour. Glad it got fixed in the end as I didn't realise how much I actually do use it until it wasn't working... (fortunately the web interface was still working as a workaround - and that works well on an iPhone, although it is annoying to have to log into vs the saved login in the app)
I had a brief TCC disconnect this morning and I received 2 identical loss of connection e-mails followed by 2 reconnected e-mails a couple of minutes later. I wonder if Honeywell are running 2 servers because of recent issues?
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