Replacing 2 zone multi-zone central heating system with HIVE

[JaseC]

I am currently looking at replacing the control system for my CH with Hive but I am unsure exactly what I will need.

Currently the system consists of a Honeywell st9100c single channel switch next to the boiler and 2 Honeywell cm907 thermostats; one upstairs and one downstairs.

The st9100c is on the continuous setting always and the heating is then programmed to operate at different times upstairs and downstairs.

I was pretty confident in what I needed to replace the current setup but then I read another thread and now I'm not sure.

Any advice/help on exactly what I need would be gratefully received.

Thanks.

 

[stem]

As the Honeywell cm907 and the Hive are both programmable thermostats with inbuilt time control, there isn't any need for the Honeywell st9100c, so I have no idea why its there now.

You don't mention any hot water time control, so I assume that you have a combi boiler for instantaneous hot water and not a hot water cylinder.

If the above is correct, you would need two Single Channel Hive Receivers and Thermostats, one of each for each heating zone.

The existing wiring at the two Honeywell cm907 thermostats would then go to the two single channel receivers instead, but the problem here, is that the Honeywell cm907's are battery powered, and the Hive receivers are mains powered. This means there is unlikely to be the required 230V mains supply from the boiler fused connection unit present. (very occasionally the N and L wires are there but not connected)

If you don't have the 230V present, and with the superfluous st9100c, It will probably be easier to start again from scratch, than try to modify what you have already. But, to do either you would need to be competent electrically and have a working knowledge of heating systems their components and how they relate to each other. Unfortunately this is not an installation where simple instructions regarding moving wires from one terminal to another can be given over a forum.

 

[ericmark]

I would start by asking the question, what do I want to achieve? There are now loads of systems with internet linking including geofencing, but personally I was rather disappointed with response times. It is no good dropping the temperature upstairs during the day on a thermostat, if the temperature simply does not drop.

I found enough heat goes up the stairs to keep it warm even with heating off up stairs. It is now 4:30 am, heating switched off at 11 pm but living room still at 18°C which is the target temperature. The house simply holds the heat, so although I have four electronic heads on my TRV's to control the main rooms, in real terms all it does is stop room over heating, setting the bedrooms to cool during the day is pointless as it simply does not happen.

This clearly changes house to house, but what benefit are you expecting by fitting Hive? I can see the benefit monitoring the house in case heating fails when you don't live there, however I did that with a pet cam with my mother. If the temperature was wrong, some thing had failed, so it needed a visit, no amount of adjusting temperature will work if fiddling fingers has switched off the boiler.

I paid a lot of money for my electronic heads around £200 for 4 heads and a hub, I see I could have bought 4 heads for £70 if I didn't want to be able to use internet to alter them, and at the speed rooms heat and cool in hind sight (always easy) I didn't need internet control.

I intended to install Nest, and I selected the electronic heads with the idea they would interconnect with Nest, however all rooms now doing what I want with the old thermostats so never actually fitted Nest. So I now have all the control I want without doing any wiring. OK may not work for you, but before going to all the work of rewiring, ask yourself will wireless TRV heads do what you want without changing a single wire.

I am not saying what I have is perfect, but it is now good enough.