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Hi all,

I’ve been looking to install Hive in a central heating system made up of:

Glowworm Xtramax HE boiler
Honeywell ST9100C timer
Honeywell rotary thermostat (unsure model number)

I’m not having much success as the wiring has me very confused. I’ve previously installed hive but never seen anything like this.

System has the timer in the kitchen, the thermostat in the hall (complete opposite side of the house) and the boiler in the garage. What I believe is complicating matters is that after speaking to a neighbour I found out the position of the boiler in the garage was moved late in the build from the middle of the wall to the back corner. This has left the junction box below in the middle of the garage.
junction box.jpg



Original plan was to simply replace the timer in the kitchen with the hive receiver, disconnect and mark the wiring to the original thermostat as disused and cover up the holes. Now I'm thinking it is probably best and easiest to install the receiver in the garage adjacent to the boiler and take spaghetti junction out of the equation.

Can anyone offer some advice on wiring it in? Confused by blues joining blacks etc in the pictures. All help much appreciated.

thermostat.jpg
timer.jpg
 
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CBW

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Yep, colours mean nothing in a heating system. It’s likely they’ll be switched lives. For the thermostat you can joint the 1 and 3 up, unless you can trace it back?
 
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Provided that the system was working properly, If I were you, I would put the junction box in the garage back exactly as it was. Then replace the Honeywell ST9100C with the Hive Receiver (Single Channel Version)

capture-jpg.137269


h.png


The existing wires move from the ST9100 to the Hive receiver, you can see from the diagrams above that the terminals are like for like, with the single exception of the wire in the ST9100 terminal 4 (heating on), which will go instead to Hive receiver terminal 3 (heating on)

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 professional way would be to find the origin of the thermostat cable. Note where the wires are connected and disconnect the cable completely. Then link the terminals where the two switching wires that went to the old thermostat terminals 1 and 3 have just been removed from so that they are electrically connected.

Alternatively set the old thermostat to maximum and make sure it stays there, or join the wires in thermostat terminals 1 & 3 together as per at @CBW above.

I think that this is the simplest way to proceed from a DIY viewpoint, if you want to lose the junction box in the garage, then the existing wiring would be removed and the whole lot wired up from scratch as if it was a new installation.
 
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Provided that the system was working properly, If I were you, I would put the junction box in the garage back exactly as it was. Then replace the Honeywell ST9100C with the Hive Receiver (Single Channel Version)

capture-jpg.137269


View attachment 257872

The existing wires move from the ST9100 to the Hive receiver, you can see from the diagrams above that the terminals are like for like, with the single exception of the wire in the ST9100 terminal 4 (heating on), which will go instead to Hive receiver terminal 3 (heating on)

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 professional way would be to find the origin of the thermostat cable. Note where the wires are connected and disconnect the cable completely. Then link the terminals where the two switching wires that went to the old thermostat terminals 1 and 3 have just been removed from so that they are electrically connected.

Alternatively set the old thermostat to maximum and make sure it stays there, or join the wires in thermostat terminals 1 & 3 together as per at @CBW above.

I think that this is the simplest way to proceed from a DIY viewpoint, if you want to lose the junction box in the garage, then the existing wiring would be removed and the whole lot wired up from scratch as if it was a new installation.

Thanks for the detailed reply Stem.

The wiring is really difficult to trace so I was planning on joining the thermostat wires 1 & 3 together then clearly labelling them incase any future work should take place.

Whats confusing me is that only a live and a neutral wire were connected to the ST9100c. No boiler on / off connection. Here is a picture of the wiring at the ST9100C in more detail.

st9100C wiring.jpg


Two separate cables coming in -
Cable 1 Has live, neutral and earth with the live and neutral connected to the timer control and the earth connected to the metal back box.
Cable 2 has brown, black and grey wires along with an earth within. The brown and black are connected together in a terminal block / chocolate block. The grey isn't connected to anything. Earth connected to the metal back box.

Really confused. I'd have thought the timer would activate and be connected to the thermostat directly to control but clearly not. How can I work out the boiler on line without having to dismantle everything and try tracing wires all the way back to the boiler?
 

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Probably bypassed then, just using the thermostat?
 
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just rip the lot out and start from scratch takes about 40mins, permanent L&N from boiler to L&N on hive, 1&3 on hive to external heat link at boiler, job complete

DO NOT MAKE ANY LINKS your boiler uses volt free switching only
 
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just rip the lot out and start from scratch takes about 40mins, permanent L&N from boiler to L&N on hive, 1&3 on hive to external heat link at boiler, job complete

DO NOT MAKE ANY LINKS your boiler uses volt free switching only
Thanks Ianmcd.

Having looked again I can easily identify the power in cable in that junction box going to the boiler.

So I take everything else out the equation and take power straight to the boiler. Then I wire back out to the hive receiver direct from the boiler. What cable should I ideally use for this? Would I be right in thinking I need 5 core? Does it need to be heat resistant or any specific spec?
 

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Ideally 5 core yes and heat resistant flex cable - can buy it in 5m coils, or by the metre in places.
 
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I always use 0.75mm2 5 core, but because I buy it in 100m drums as I use a lot of it, you can buy it by the meter though, you only actauly require 4 cores to do what you need as the hive doesnt need an earth
 
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just rip the lot out and start from scratch takes about 40mins, permanent L&N from boiler to L&N on hive, 1&3 on hive to external heat link at boiler, job complete

DO NOT MAKE ANY LINKS your boiler uses volt free switching only

Thanks once again ianmcd, Hive successfully installed today. Everything good first time and works like a charm! Much appreciated.
 
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Thanks for posting the outcome. always helps others with similar problems to know you got it sorted
 
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