Swapping digital thermostat

[Sparky98]

Hi, I need to swap over this digital thermostat to a new one as this old has stopped working. I've purchased the "Drayton Digistat Wireless Thermostat" as I thought they looked pretty much identicle.

When I got to the property, the one in the photo below is screwed onto the wall, just a battery powered, wireless thermostat. But I wasn't able to find a reciever by the boiler or anywhere else. The boiler just has a fused spur with a 3 core flex into the boiler to power it.

I don't understand how that thermostat could've ever worked? Unless it's programmed directly into the boiler somehow? (As you can tell I'm not massively clued up on heating systems).

So I was expecting to see a reciever, swap that over with the new and link the new thermostat up. When I couldn't find one, I didn't think it'd be an issue as I can just wire a new 5 core cable directly from the boiler into my new reciever but unfortunatly can't access the wiring for the boiler as somebody has built a huge built in wardrobe set covering it!

So I'm returning in a week or so once they customer has had someone cut the wardrobe so I can gain access properly to the boiler. I just wanted to go back knowing exactly what's needed. Can anyone explain how the old would've worked?

Thanks

Edit: Have attached a photo of the boiler.

 

[jj4091]

Is it the circular part in the middle of the control panel

 

[ericmark]

As said the receiver is in the boiler

I have looked at these a few times, there is a plug inside so the receiver can be swapped or removed, but one needs to be gas safe registered to remove covers, so always refused the work. OK as a DIY breaking the rules, but as a job, not worth it, just back heal the job.

 

[Stuckinarut]

Speak to Drayton technical or Worcester technical and see if they can advise? Have you tried replacing the batteries, and for good quality ones?