Replacing Honeywell with Hive!

[Redwreck]

Hi All!

I’ve been researching the installation of hive in place of our current system which is a Honeywell ST9400c.

Our set up is boiler and water cylinder, with two thermostats controlling both upstairs and downstairs.

I’ve pretty much got my head around the process but quickly losing confidence one I crack the junction box and stare at the tin of spaghetti inside. I have the correct hive bits, two receievers (one water and heating, the other heating)

From my understanding I can switch out the Honeywell programmer for the Hive receiver with like for like wiring.

Then I need to address the downstairs thermostat by disconnecting it and capping.

Where I’m losing my head with this is within the junction box, what I’m reading and watching is telling me to trace the wires from stat to junction box to figure which is which, this is not possible without pulling my walls apart.

There junction box has 3 cables running into the back left coming from each of the 3 port valve boxes at the cylinder. Is the thermostat likely to be one of these cables, this doesn’t make sense to me but after that I’m at a loss!

I’ve attached images of the set up at the boiler and the water cylinder (where then junction box lives)

If somebody could break it down for me that’d be great! I’m aware I’m not mentioned the upstairs circuit, I’m just trying to get my head around downstairs first before tacking the second leg of the job!

TIA!

 

[CountryFan]

Do you have any testing equipment?

 

[Redwreck]

Do you have any testing equipment?

Yes I’ve got a multimeter, I’m planning on a process of elimination approach, remove cable, turn on electrics, test the stat with multimeter.

Would this be a way to tackle it?

The more I read into this, I’m now thinking that actually those 3 cables running into from the valves are likely to be the 2 of them thermostat? Is this likely?

 

[CountryFan]

Yes the stat gets a live from the programmer or depending on the control if separate. Which is the one you're replacing? Post a photo please

 

[Redwreck]

Yes the stat gets a live from the programmer or depending on the control if separate. Which is the one you're replacing? Post a photo please

Thanks!

I’m not a home to get pics of the kit there but ultimately these. The programmer is a Honeywell st9400c and the stat a bog standard.

I’ve read about dark arts of connecting live and switch live at the stat, from what I’ve read it’s frowned upon but if that’s the easiest route? Otherwise I’m still looking for the way to remove the stat.

 

[CountryFan]

Thanks!

I’m not a home to get pics of the kit there but ultimately these. The programmer is a Honeywell st9400c and the stat a bog standard.

I’ve read about dark arts of connecting live and switch live at the stat, from what I’ve read it’s frowned upon but if that’s the easiest route? Otherwise I’m still looking for the way to remove the stat.

Ok, so if this is accurate. Turn the heating on via the programmer, turn the downstairs stat up to maximum and turn upstairs stat turned down to minimum. You should then be able to test for mains voltage between earth and the black wires which meet the brown wires feeding the motorised valves, whichever gives you 230Vac is the downstairs stat.

Yes you can link live and switched live at the thermostat, turn up to maximum and leave on the wall, What's frowned upon/not permitted is hiding the join buried in the wall.

 

[Redwreck]

Ahh brilliant! I’ll try that mate!

One final question!

In regards to the back wires meeting the brown wires to feed the valves . Am I looking at the situation back to front.

The three cables that enter the top left of the junction box are off the motorised valves. Will the stat cabling be on the opposite side of them, in the bottom row of cables? That’s be swell if they are, it’s the top row that’s been keeping me up at night!

 

[Redwreck]

Ok, so if this is accurate. Turn the heating on via the programmer, turn the downstairs stat up to maximum and turn upstairs stat turned down to minimum. You should then be able to test for mains voltage between earth and the black wires which meet the brown wires feeding the motorised valves, whichever gives you 230Vac is the downstairs stat.

Yes you can link live and switched live at the thermostat, turn up to maximum and leave on the wall, What's frowned upon/not permitted is hiding the join buried in the wall.

Ahh brilliant! I’ll try that mate!

One final question!

In regards to the back wires meeting the brown wires to feed the valves . Am I looking at the situation back to front.

The three cables that enter the top left of the junction box are off the motorised valves. Will the stat cabling be on the opposite side of them, in the bottom row of cables? That’s be swell if they are, it’s the top row that’s been keeping me up at night!

 

[CountryFan]

In regards to the back wires meeting the brown wires to feed the valves . Am I looking at the situation back to front.

The three cables that enter the top left of the junction box are off the motorised valves. Will the stat cabling be on the opposite side of them, in the bottom row of cables? That’s be swell if they are, it’s the top row that’s been keeping me up at night!

Yes the 3 black cables are your motorised valves, they have brown wires which become live when the room stat is calling, which then open up, touch a microswitch and make the grey and orange live sending the live (switched live) to your boiler to come on. So, yes, the brown wires from the valves to the black stat wires

 

[Redwreck]

Okay Jobs a good one!

Located the stat wires and removed entirely.

I’m now racking my head about the bridge here, I’ve yet to put one in, just looking for input.

my question is, at terminal one, the live wire (brown) from the stat shared a terminal with a black wire. Am I okay to bridge from the terminal the switch live was in over to terminal one? Currently have no hot water but need to contact hive to resettling my hub!

 

[CountryFan]

You could bridge that, but are you sure that’s where the stat was connected? I thought it would go to a motorised valve

 

[Redwreck]

Definitely not sure! The black cable I disconnected from here was the only one from this bottom row that had a change when the stat was turned on. Weirdly though it was idling around 70v and when stat was turned up it went to 240v. Tested the stat afterwards and cables were out other than 3v on a live running into it which I thought may be residual?

Possibly mucked it up? I thought you meant these wires at the bottom that were likely to be that stat, the three thick cables at the top and the wires inserting in the top row are from the valves.

In any case, finally just got access to the app and tested both heating and hot water and both are not working, so in a pickle!

 

[CountryFan]

Yes the ones at the bottom are supposed to be the stat ones. Right, do me a favour, the red marked photo that you posted recently, which one was 240vac when the stat was live/turned up?

 

[Redwreck]

Hi!

It was the black cable 2nd in from the left at the bottom marked with green arrow!

The new hive stat fires up the boiler but no action so assuming I’ve cocked something up wire wise!

 

[Redwreck]

Hi!

It was the black cable 2nd in from the left at the bottom marked with green arrow!

The new hive stat fires up the boiler but no action so assuming I’ve cocked something up wire wise!