Ideal Logic+ & Opentherm

[nicke]

Hi all.

I've had an Evohome setup running for about 6 years now, but have just had to replace my old boiler. I asked for an Ideal Logic+ as I knew it supported OpenTherm. I got the installer to just leave it on the BDR91 initially, to make sure it was working ok, which it was.

I've now installed the OpenTherm bridge, but not much seems to be happening. The bridge paired ok, I've changed the Boiler Control setting over to OpenTherm, and a comms check from the control box shows 4/5 on the bridge.

The central heating pump line was doubled up on the switched live input on the boiler, so I've moved that to the switched live output terminal. And then just yanked out the BDR91 which was previously controlling the boiler. I still have another BDR91 which I use to open the valve to the DHW cylinder.

Initially the boiler did fire a bit. But this evening we are sitting here with several rooms below their target temperatures, and yet the boiler is not firing. Also, I'm pretty certain the pump has been running continuously since I moved it to the switched live output.

In desperation I've replaced the BDR91 faceplate and the boiler has leapt back into life.

Any ideas what I'm doing wrong? Do I need to reset the BDR91 before unplugging it? Do I need to change another setting somewhere in the boiler or Evohome? Is the DHW BDR91 confusing things?

Thanks in advance

Nick

[nicke]

Actually, I've just realised the Switched live output is permanently live, so that's not going to be any use for a pump demand. How are you supposed to trigger the CH pump if controlling the boiler via the OpenTherm bridge?

[Richard]

A couple of articles here...

viewtopic.php?f=5&t=4082

viewtopic.php?f=5&t=4114

Not sure if they help?

[nicke]

Ah, so the idea is just to short the in and out terminals. That makes sense. However it would still leave me with no way to trigger the CH pump upstairs in the airing cupboard.
I've just left the BDR91 connected, as that runs the pump and enables the boiler to fire. Despite the tech support guy on the Resideo telephone helpline insisting that OpenTherm wouldn't work until the BDR91 was disconnected, it does seem to be working. The boiler shows its target output temperature on its screen, and it drops from 57° (the limit I've set in the menu) to 30-something°, I think, as the house reaches temperature.

I think I'll leave it as it is.