Honeywell Evohome - Off, but on

In May we had a (brief) period where the weather was fantastic, and I decided to turn the central heating off using the Quick Action on the Evohome controller. It was then a bit of a surprise to feel that a couple of radiators were still being turned on, confirmed by the green light on the BDR91 wireless relay in the airing cupboard.

After a bit of internet searching I came across this Knowledge Article from 2018 on the Honeywell Support website:

https://ensupport.getconnected.honeywellhome.com/s/article/The-evohome-controller-and-radiators-are-in-off-setting-but-the-boiler-continues-to-fire?language=en_US

It appears the two main reasons in the list that applied to us were a) weak batteries and b) loose adaptors. A couple of the HR92 TRVs had been knocked, and so weren't tight to their valve adaptors, which meant that they couldn't completely shut the valve. And my experiment using rechargeable batteries in the HR92s was causing me more work in comms faults and recharging them than it was saving me in money.

So I've gone around and changed all of the HR92 batteries back to non-rechargeable alkaline batteries, as well as the two AA batteries in the CS92 storage cylinder water temperature sensor. I bought a pack of 50 Duracell Industrial AA batteries from Amazon, working out at less than 32p per battery. There's no mAh capacity rating on the batteries or packaging, so we'll have to see how long they last.

Honeywell Evohome - Multiple Bindings

For a while now each evening there's been a Comms Fault message on the Evohome Controller. But the heating has been working fine, so I've pressed on the checkmark and ignored it, thinking that some random external interference had interrupted communication between the Controller and the heating BDR91 wireless relay in the airing cupboard.

But looking at the system log this fault was happening at exactly the same time every evening, which made the chances this was random very slim.

Some searching on the internet brought up some advice from Richard Burrows at the Evohome Shop, which suggested that the Controller and BDR91 could have multiple duplicate bindings. Thinking back I did have to rebind the BDR91s after a power cut, and I've probably got the system into a situation where the Controller and BDR91s are bound to each other twice. So the solution is to clear the bindings, and rebind the Controller and BDR91s afresh. However the key is clear the bindings at both ends, i.e. not just at the BDR91s.

So first use the long press on the Settings button on the Controller to get into the system settings. Then set the System Devices and set the Boiler Demand and Sundial Valves to None.

The inconsistent naming in the Evohome Controller really annoys me. "Boiler Demand" on the System Configuration page becomes "Boiler Heat"...

... and "Sundial Valves" becomes "Hot Water Configuration".

Both Boiler Demand and Sundial Valves set to None.

With the two BDR91 bindings cleared at the Evohome Controller, now pop off the front fascia and remove the batteries.

To clear the bindings at the BDR91s in the airing cupboard, hold the button on them down for about 15 seconds. After about 5 seconds the lower red light will "long flash", and then after 15 seconds the red light will "short flash". Once in "short flash" the binding has been cleared.

Back at the Controller I replaced the batteries and fascia, confirmed the date and time settings, and then long pressed the Settings button to get to the system settings and the System Devices page.

I rebound the hot water BDR91 first by setting it to Stored Hot Water. The first thing to rebind is the CS92 storage cylinder water temperature sensor. Hold the button down on the CS92 for about 5 seconds, when the button/light will start alternating between green and red. Then press the button again, and the controller should detect the CS92.

Next the Controller asks whether you've got a "2 or 3 port valve" or a "hot water valve". Our system is a Sundial Y-Plan, so the correct setting is a "hot water valve", but it is a little confusing as it has a mid-position valve, which is a valve with 2 ports. Anyway, a 5 second press on the hot water BDR91 to get it into binding mode, and then a press on the Bind button on the Controller and the two are paired again.

Likewise the Boiler Demand is set back to Boiler Relay, and a 5 second press on the heating BDR91 and a press on the Bind button on the Controller, and everything is re-binded (rebound?). Hopefully this has done the trick, and regular Comms Fault messages are a thing of the past.