Replacing Potterton EP2002 with Hive controller - no CH

[nickynibbles]

Hi all, i'm having an issue DIY replacing a working Potterton EP2002 controller with a Hive system whereby the Potterton Suprima 50 boiler isn't firing when CH is selected. The Hive system is fully set up and has all correct status etc indicator lights. The thermostat triggers the controller for CH, the CH light comes on, but no boiler fire up. The HW circuit operates correctly and will fire the boiler.

This is the existing wiring to the EP2002:



So pin 3 is HW on and pin 4 is CH on.

Looking at the hive wiring diagram:


I just connected HW on to pin 3 and CH on to pin 4.

On the EP2002 there was a live connection made to pin 5 which is CH off, should I replicate this with the Hive and bridge the live and pin 2 terminals? Didn't want to experiment in case this makes the Hive go pop and i've wasted a load of money!

OR, should there be something done with the old thermostat which has been disconnected now and wires terminated in a block?

 

[Echo the husky]

No connection 5 on the old controller is the common to the HW relay contacts, this connection is made internally in the Hive. I assume you have 2 2 port valves, one for heating one for HW?

You need to fully disconnect the old thermostat cable, then fit a wire link in its place between L ans SL. The room stat is likely to be the cable connected to terminal 4 of the old and new programmers. It is not clear which wires are in the same cable as that red wire in your photo, but the switched live from the room stat will likely connect to terminals b or c. Once the room stat cable is fully disconnected, the wire the switched live was connected with will then go into terminal 4 on its own.

 

[nickynibbles]

Thanks for the reply. Having checked in the airing cupboard with the HW tank there are 2 motorised valves hooked up to the 22mm feed pipes, one just before the HW tank inlet and the other before a junction heading off into the floor, so presuming this is as you've described with one to control HW and the other for CH.

Here is the wiring for my stat:


I presume this is N, L and switched live?

To answer your question on the wiring in the controller, the red wire going to pin C, the yellow wire with a red sleeve going to pin B and a blue neutral wire are all from one cable. The red wire on pin 4 (CH on), the yellow wire with red sleeve on pin 3 (HW on) and a blue neutral are also all from one cable:


All the cabling is buried in walls so difficult to trace anything! I perhaps need to check the wiring colour in the boiler itself and the fused spur feeding the controller to check what is what, but it does look likely the yellow wire with red sleeve connected to pin B could be the switched live from the stat. Is there a way to continuity test this when the ends are a long way apart?! So would simply putting this wire on to the Hive pin 4 for CH on do the job? And would I just leave the black wire also connected to pin B unconnected?

Thanks for the guidance!