Drayton Wiser controller fires boiler when turned on-Cant turn boiler off

[topgazza]

My system is an unvented S plan with a trusty Potterton Profile 50e boiler

I have a Drayton 722 controller at present so the Wiser Controller is a like for like swap. But as soon as I turn the controller on the boiler fires up and the radiators get hot. There are no lights in the CH or even the HW on the front and even when I connect the Wiser room stat and reduce the temperature the boiler still runs. I can turn heating on and off at the app and the relevant lights go on and off on the controller front but nothing stops the boiler running. I have joined the two thermostat wires together in a Wago at the wall as required.

I fitted the 722 back on and everything works OK with a Netatmo room thermostat controlling the CH as before. Before I send it back to Amazon for a replacement in case its faulty has anyone got any ideas please ?

 

[Deleted member 267285]

If it works before changing it over, then I’d say duff unit.

 

[topgazza]

It seems obvious I know, but that's my thought as well

 

[topgazza]

I get the boiler firing up straight away as the wired room thermostat is effectively on maximum being shorted out in the wall. But not the fact that the Wiser controller doesn't appear to turn it off even though the Wiser thermostat is below the room temp. Anyway, its on its way back to Amazon and a replacement will be here today

 

[topgazza]

Fitted the replacement Wiser Controller but still the same issue. So I did a bit more experimentation. If I separate the two wires in the old thermostat the boiler stops. I then remover the HW and CH call for heat wires from the wall plate (3&4) so the only wires going to the controller are live an neutral. Guess what ? The boiler still fires up and rads get hot. I suspect something fundamental with the wiring centres. I say centres because there is one next to the controller and another in the loft conversion next to the cylinder. The latter is almost impossible to get at behind several pipes in a tiny cramped cupboard which might explain a wiring issue and failure to fix it. However whatever they did 20 years ago actually works so they probably did a work around. My plumber did say a while ago that it looks like two wires were reversed but clearly everything works. Doesn't explain why it works normally but the Wiser fires the boiler a soon as its turned on regardless of what's connected.

I know I should explore the wiring but even as an ex electrician I would prefer leaving CH wiring to an expert. Sending the second Wiser back to Amazon and I'll have a word with my plumber. But despite not being able to see the wiring has anyone any thoughts on this weird setup and why the boiler fires up without a call

 

[Deleted member 267285]

Yep, does sound like a wiring fault then.

 

[ianmcd]

post pics of the wiring that you can get access to, especially the boiler end

 

[topgazza]

To be honest Ian it’s a complete rats nest and not in any laid out wiring centre. It was done in 2003 when had a loft conversion and unvented system installed. I would be embarrassed to show my face if I’d installed it. I’ll take pictures and you can see. But make sure you’re not eating. The pics aren’t going to help I’m afraid
To be fair the wires are currently exposed as my great plumber has just pulled them out to fit in a Wago box. But I’ve asked him to re-site the box to the right, in the first picture,away from the pipes into an s plan type box.

 

[ianmcd]

yes its a mess alright, but its a simple S plan, from the factory wiring from the 2 motorised valves you should have 2x grey wires in the same terminal, connected to a permanent live, and 2 x orange wires connected in their own terminal and the orange wires go to the boiler switched live, is this the case ?

 

[topgazza]

As far as i can tell but I'm feeling paranoid enough that Ive asked him to start from scratch. Its really difficult to fault or test circuits as it is

to get a full picture, literally. And its a small cupboard. I'm a believer in starting from a clean slate in situations like this. I would have done it myself but as it all was working, and is now with the Drayton 722 back in, I have left it. But as I say, time to sort it out. Even if its just for future owner or plumbers. Luckily I have a good guy on the job. I'm too old to fit in that cupboard anymore

Hopefully that will resolve the smart programmer "issue"

 

[ianmcd]

can you post a pic of the netatmo room stat and which model it is please

 

[topgazza]

They just call it The Smart Thermostat. It uses the existing wires to switch heat on and off. Have to say it works very well and is very accurate. The Drayton 722 likes it as well.