Hive 2nd zone

[Ashley06]

Need a little help! I installed a Hive thermostat to control the ground and 1st floor (annoyingly they share a valve) and all went well, recently the thermostat display on the top floor has died and so I decided it was time to update it to a Hive, I can get it powered up but I can’t get it to activate the motorised valve.

First pic is how the main thermostat is wired up and controls the ground & first floor heating and the hot water.

Second picture is of the thermostat I’m replacing, this has N/C - COM - N/O connections of which N/C was unused.

This is how I’ve used the existing wires from removing the Danfoss controller for the new Hive thermostat:

I’m not an expert but this seems to only give me power to the thermostat and doesn’t control anything, which I’m slightly confused about as the previous thermostat only used these wires and worked perfectly until the display gave up.

Am I short of some wiring? Do I need to bridge a connection?

 

[ericmark]

The orignal wires are control not power, so to use them the thermostat needs power from else where be it battery or other.

 

[RandomGrinch]

To expand on the above, your existing brown and black wires are not a Live and a Neutral - they are a Live and a switched Live.
Your Hive is powering up, because the connection to the switched live, through the zone valve is acting as a false neutral.
This isn't a good way to power the Hive, and without the switched Live connection to the valve, it ain't going to do much!

As your cable has a brown, black and earth wire, there may be another grey wire hidden behind the Hive backplate.
If this extra wire exists, you may be able to use it as a Neutral wire to power your Hive.

You will also need to find where the other end of this cable goes (probably the wiring centre?)
If this grey wire exists, there is no guarantee that it is connected to anything at the other end.

Lastly, is this new 'stat a single-channel Hive?

 

[ericmark]

The question is do you really need to turn off a group of rooms? I do, as 4 rooms on lower floor (The flat) are often unused, so it has it's own zone valve and pump. But in the main house, the 10 heated areas are independently controlled with TRV heads, except for bathroom, so there is no point in having any further zone valves, the TRV heads do that.

When changing the method of control, one needs to consider if the new is making the old redundant, so it is likely you don't need a second thermostat any more after fitting programmable TRV heads.

However if you do then the Hive thermostat is independent to the switching module, so the switching module will go near the motorised valve and the thermostat position does not require any wires, it is wireless connected to the switching module, and powered by batteries, and they also wireless connect to a hub (Zigbee) which in turn either wired or wireless connects to the router and is powered by 5 volt.

The main point is there is no need for the switching module to go where the original thermostat went, it will likely be mounted next to the wiring centre.

 

[Ashley06]

Cheers for the replies, I think I'm going to get someone in. I looked at where the wires go into and it's just a load of wires crammed together into a cheap terminal connector block which is then rammed into a hole in the wall. That is a bit too much for me to take on and I'd like it done correctly!

 

[RandomGrinch]

Cheers for the replies, I think I'm going to get someone in. I looked at where the wires go into and it's just a load of wires crammed together into a cheap terminal connector block which is then rammed into a hole in the wall. That is a bit too much for me to take on and I'd like it done correctly!

Good call.
If you would like a second opinion, post a photo up here and we can take a look

 

[Ashley06]

I started by looking at the valves and seeing where they went and found this:

The wires don’t match what’s behind the thermostat but if that is like that, I’ll need someone in anyway and they will likely be able to sort it much quicker and safer than I can.

 

[RandomGrinch]

The wires don’t match what’s behind the thermostat but if that is like that, I’ll need someone in anyway and they will likely be able to sort it much quicker and safer than I can.

Did you look behind your existing thermostat, and find an extra grey wire, that I mentioned earlier?

If I were to investigate further, I would start with this grey wire, that isnt connected to anything.
Although it's a busy wiring centre, it is neat, and the wires have been oversleeved - except for this one...

A proof of concept - disconnect the black wire (safely isolating it), directly below it (coming from the same cable) - and see if the zone stops working.
The grey could then be connected to a neutral and your Hive could receive power.

 

[Ashley06]

Turns out I do have a grey wire behind the thermostat. I’ve had it off to try and neaten the area up and found it.

I don’t believe it’s a neutral though. I had a go at working out where it leads but it’s not the boiler and it isn’t the junction box as the wires are different.

 

[RandomGrinch]

I don’t believe it’s a neutral though. I had a go at working out where it leads but it’s not the boiler and it isn’t the junction box as the wires are different.

You`ve said before that the cables are different, but did you try this?

A proof of concept - disconnect the black wire (safely isolating it), directly below it (coming from the same cable) - and see if the zone stops working.

 

[Ashley06]

Hi all, I've been let down a couple of times so I knocked all the power off while it was light and had another look at this, I've traced the wires as follows however it is very confusing as all the colours are mix matched. Apologies for lack of terminology, I'm not an expert, I just like learning how things work. (I am doing this safely, probably over kill as I'm killing all power to the house and then confirming with a tester, I haven't made any changes to any wiring, I'm just looking/trying to work out what's going on).

You`ve said before that the cables are different, but did you try this?

This controls the top floor valve, at the minute i have no way to power the valve so I can't test this. The valve currently doesn't activate

My investigation:

The valves are Danfoss HPA2 and each has 4 wires as follows:
Brown - Live
Blue - Neutral
Orange and Grey which seem to be a switch as illustrated below

These have been chased through two junction boxes and lead to three cables which again have the normal wires, Brown/Blue/Grey/Black/Green+Yellow (Green and yellow is not used on the valves so I'll skip these)

Cable 1:
Black (over sleeved black) goes to the brown for the valve controlling the ground floor zone
Grey (over sleeved black) does not go to the valves
Blue goes to the blue for all valves
Brown goes to the grey for all valves

Cable 2:
Black (over sleeved black) goes to the orange for all valves.
Grey (over sleeved black) does not go to the valves
Blue goes to the blue for all valves
Brown goes to the grey for all valves

Cable 3:
Black (over sleeved black) goes to the brown for the valve controlling the top floor zone
Grey goes to nothing, it ends at the first junction box.
Blue goes to the blue for all valves
Brown goes to the grey for all valves

To put it another way:

Ground floor valve:
Brown - Black (over sleeved black) from cable 1
Grey - Brown from all 3 cables
Blue - Blue from all 3 cables
Orange - Back (over sleeved black) from cable 2 (grouped together with the orange from all 3 valves)

Top floor valve:
Brown - Black (over sleeved black) from cable 3
Grey - Brown from all 3 cables
Blue - Blue from all 3 cables
Orange - Black (over sleeved black) from cable 2

Cable 2 is underneath Cable 1, it's difficult to see in this image.

I believe cable one controls the ground floor zone and cable 3 controls the top floor zone, cable 2 appears to be the other side of the valve switch (orange).

I'm a bit confused on if orange and grey within the valves are the switch, how they are all grouped together, I am assuming the switch is closed all the time and in order to enable the valve it is powered via the brown live.

Considering I do not have blue coming up to the thermostat on the top floor, my next step is to buy a wire tracer and identify which wires go where. I only have Grey/Brown/Black and Earth which do not match any wiring that terminates at the valve! I did wonder that as the old Danfoss TP400 did not use an earth, and all the colours seem to be a pick 'n' mix, whether this earth wire was repurposed.

TBC!

 

[CBW]

Wow, that’s hard to follow. From what I can deduce, the grey wire s isn’t connected - can you get this to a neutral inthe wiring center? If not, position the Hive receiver for top floor where the main wiring center is, and then link live and switched live behind the old one (top floor). Also, the grey and orange only become switched live (linked) when the brown wire has powered the motor open and made the microswitch inside the Danfoss HPA2.

 

[Ashley06]

Wow, that’s hard to follow. From what I can deduce, the grey wire s isn’t connected - can you get this to a neutral inthe wiring center? If not, position the Hive receiver for top floor where the main wiring center is, and then link live and switched live behind the old one (top floor). Also, the grey and orange only become switched live (linked) when the brown wire has powered the motor open and made the microswitch inside the Danfoss HPA2.

Its awful! I could move the grey wire to a neutral, but right now I'm not 100% sure where the other end of that wire is as on the top floor both the brown and grey wires carry a current and the black wire is dead.

The cable behind the two thermostats is 3 core and earth where as all of the other cable going to the valves is 5 core flex. I'm not sure where or how they all join together so it's hard to link it all together without a tracing machine.

 

[CBW]

If the black wire isn’t dead, did it (the heating) not work before?

 

[Ashley06]

If the black wire isn’t dead, did it (the heating) not work before?

Heating worked fine, I believe the old thermostat (TP400) used the brown wire into the com port and the black wire into N/O (I wish I'd taken a photo!), I believe the black is the switched live as said above by RandomGrinch. The old thermostat used batteries though.

I've also realised I've got a dual channel receiver (now I know what that means) which isn't ideal, I should have got single channel. I've researched on this site and seems to be mixed opinions onto if the dual channel receiver can run single channel but it does seem possible. (My boiler isn't ELV).