Bit of a longshot, but anyhoo….

Came home to find the heating not on. We’ve got a Honeywell wireless controller ST9420C and wireless thermostat DTS92E.
The controller was showing ‘no signal’ and the radiator symbol was flashing. This apparently means low battery on the ‘stat.
The thermostat was flashing the wireless signal but not showing the ‘low battery’ symbol.

I swapped the batteries for a set of rechargables and it initially showed the ‘sync’ word and after a while it did then show the low battery symbol. So we tried another set of batteries.

It wouldn’t connect.

I then did a signal strength test from the installer manual and it said zero, and as a result of that it recommended doing a bind procedure.

Basically, it wouldn’t re-bind so I thought I might have to cancel the existing ‘bind’ and re-do it.
So…I tried that & it doesn’t want to do it. Once I reset the bind, the heating started straight away. I guess it is now running autonomously without the thermostat – I seem to remember it has it’s own thermostat internally?

So now we have a thermostat that won’t connect at all to the controller. I have tried the bind procedure about 50 times now and it doesn’t want any of it?
Any ideas? Is the thermostat borked? I won’t be happy if it is as it’s only a yr or so old & a new one is about £75.
Just seems to be one thing after another at the moment. I just want an evening when I can come home and not have something leaking, sticking, breaking, not connecting….!

I thought that looking online there might be some other poor souls who have had this issue but I can’t find anything about it. Not really expecting it, but any help would be massively appreciated!

Not a Honeywell, but a Wooster Bosch one. Its a bit temperamental and occasionally the battery contacts cut the power on the stat. I replace the batteries and it re connects and just starts up. Once had to re connect the battery 2m away from the boiler control so it “pairs” then all is well…

Basically, just doing what you tried. manuals or on line help ?

Yeah. The manual said to ‘just put the batteries in’ and it should sync. But it didn’t. We left it for about 20 mins (it says it might take 4 mins) and it wasn’t doing anything, just displaying sync…

At that point I dug out the installer manual & tried a signal strength test. It came back with no signal strength, so I then moved onto re-binding the thermostat which the installer manual said needed to be done.
It showed that a sensor was bound to the controller, but it would not re-bind. After multiple tries I ‘deleted’ the ‘bound device’ to make the connection afresh.
At this point, the heating came on (so at least we are warm), but it will not reconnect to the controller. I have tried several different batteries, so am confident that is not an issue.

We have tried to find a ‘reset’ button on the controller, to try & get it back to factory defaults and start again in case it’s got it’s knickers in a twist, but cannot find anything. And I think even if you cut the power to it, it has a battery back-up.

Pretty miffed to be honest. I just wanted a relaxing evening, but have spent most of the time since I got home cocking around with this in the kitchen getting more & more stressed. And normally answers are pretty easy to find on the internetz…..but with this, there is nothing. Balls.

Bounce for any daytime heating people who can shed some light on this.
Gonna give honeywell a call in a bit, but not expecting much in the way of help….

You could give the support line a call, 08457 678999 (local rate number) if you still struggle.

Had a similar problem with our Worchester/Bosch but replacing batteries next to the boiler got it sorted.

Try using regular batteries instead if rechargeables? Recharrgeables are lower voltage and may not be quite enough. Long shot but easy to check

If it’s the same as our honeywell, the boiler controller has two buttons, if you single press one of the buttons it turns the heating on (just constantly on) regardless of the wireless bit.

Not sure about the rest, but that is designed to get you heating control if the wireless stat is broken.

sandwicheater – Member
You could give the support line a call, 08457 678999 (local rate number) if you still struggle.

Gonna try that in a bit I think, but I suspect that until I have tried it with brand new batteries, they will say that is the issue…

leffeboy – Member
Try using regular batteries instead if rechargeables? Recharrgeables are lower voltage and may not be quite enough. Long shot but easy to check

I did wonder that, so found some Energizers in a remote (for my rc helicoptor) – it made no difference & the thermostat was moved to the kitchen and hand held right near the controller. Prior to this, it has worked in the kitchen, dining room, living room and on the upstairs landing (we were trying to find the best location for it).
I think I will get some brand new Duracells on the way home, just in case! Would be embarassing if that was the case.

joemarshall – Member
If it’s the same as our honeywell, the boiler controller has two buttons, if you single press one of the buttons it turns the heating on (just constantly on) regardless of the wireless bit.

Cheers. The heating wouldn’t come on while the thermostat was ‘connected’ but not communicating. As soon as I disconnected the thermostat (deleted the ‘bound’ thermostat from the controller) the heating did come on. I think it runs on a 20% cycle whatever that means to keep things ticking over.

Meant to update this a while back in case anyone else finds themself with the same problem.

I rang Honeywell and the bloke asked whether I had turned off the controller before re-binding. I said no, as I figured the back-up battery would render this pointless. But apparently not.

Turned the power to the boiler/controller off & back on again. Did the re-bind thing & it worked straight away….