Removing wired room stat after installing Hive2

[JimmyMak]

Hi All,

Just a quick question for the experts.

Weve just moved into a place with a really old Potterton Netaheat 80E - (installed in 1972) and still going strong (touch wood)

The EP3000 controller got damaged by a plaster, and so I decided to replace it with a HIVE2 (dual channel)

Replacing the EP3000 seemed fairly easy, just a case of mapping the L, N, "CH ON" and "HW ON" wires from the EP3000 into the corresponding terminals in the Hive receiver. Everything seems to be working fine, however, the wired Honeywell room stat is still there. Ive uncovered the rats nest in the junction box in the airing cupboard but I'm just a little confused about something with the room stat and CH motorised valve.

The room stat is an old brown Honeywell one, and the terminals are numbered in a strange order without any description of what they are:

2 3 4 1

The N from the junction box goes to terminal 2 in the room stat. "CH ON" goes to terminal 1, and it looks like the brown wire from the CH Motorised valve goes to terminal 3 in the room stat (Im assuming this is the switch to put 240v to the motorized valve to open it. But what confuses me is nothing else is wired to this brown wire on the motorised valve.

If I just disconnect the wires to the room stat from the junction box in the airing cupboard, then nothing will be connected to this brown wire on the CH motorised valve.

So I guess my question is - do I need to re-wire the brown wire on the motorised valve to the CH ON on the HIVE ? or to something else ....as I assume that will be switched live by the Hive receiver when it gets its signal from the remote hive thermostat to open the valve for the CH

...does that make sense ?

 

[stem]

For the Honeywell thermostat the wiring is.

1=Live
2= Neutral
3= Switched Live

This information should be printed inside the cover, but in any case, it agrees with what you have put in your post. So, the switching wires are those connected to terminals 1 & 3

Because the Hive carries out the functions of the room thermostat, the old wired thermostat needs to be decommissioned to prevent it overriding the Hive. It can't simply be disconnected as this would leave the heating wiring 'open circuit' and it will not operate. The thermostat can be decommissioned in three ways, in order of preference (or professionalism) they are.

1. Find the origin of the thermostat cable. Note where the wires are connected to and disconnect them. Then link the terminals where the two switching wires (those presently going to 1 & 3) originated from together.

2. Remove the existing thermostat and replace it with a junction box, connect the two switching wires (those presently going to 1 & 3) together and isolate the neutral separately.

3. Leave the existing room thermostat in place and join the the switching wires (those presently going to 1 & 3) together in a separate connector that you can tuck away in the corner of it [Some will suggest putting them together in terminal 1. Whilst this will work, because of the presence of the neutral in terminal 2, the existing thermostats accelerator device will still be connected]

the brown wire from the CH Motorised valve goes to terminal 3 in the room stat (Im assuming this is the switch to put 240v to the motorized valve to open it. But what confuses me is nothing else is wired to this brown wire on the motorised valve.

That's correct, and as it should be. The thermostat opens the motorised valve, and then inside the motorised valve is a small microswitch that operates when the valve opens and fires up the boiler.

 

[JimmyMak]

Wow - that was quick - really appreciate you getting back to me so quickly - and so comprehensively - I owe you a beer !

 

[stem]

That question has been asked a few times already, so I only needed to copy it from one I did earlier and make a couple of tweaks so that it was applicable to what you have. And in any case you had already worked it out yourself.

do I need to re-wire the brown wire on the motorised valve to the CH ON on the HIVE?.

To which the answer is yes, because the end result of what I describe above will achieve exactly that.

 

[JimmyMak]

Wired thermostat has now been disconnected from the junction box and re-wired the MV to CHON and all seems good - have to admit was a little anxious - not so much the wiring - just powering down that old boiler (especially at the moment) - im neither superstitious or religious but have to admit I cross my fingers and say a quick payer every time I flick the power back on to that old Potterton and wait for it to fire up