8 Zones using a C-Bus Thermostat

Hi everyone,

I am looking to take over the control of my old Accent reverse cycle ducted system that only supports remote On/Off with a Clipsal 4 zone thermostat. I would like to, however, attempt to control 8 zones instead of 4.

I just happen to have four zones upstairs and four zones downstairs and was thinking of having a master 4 zone thermostat controlling the four upstairs zones (and the HVAC control of the fan coil unit and compressor) and a slave 4 zone thermostat controlling the downstairs zones. Each zone has its own cbus temperature sensor and I have some changeover relays to manage the 8 zone dampers and a relay unit for the HVAC control.

I was also thinking or writing an accessory to go with it for the homebridge-cbus plugin to control it with Siri.

Is this possible with two 4 zone cbus thermostats to control 8 zones with a common temperature setpoint, and more importantly, are they still available?

Thanks in advance

Jason

 

The Cbus thermostats were discontinued several years ago so getting hold of them will be difficult.

Aside from that, the thermostats only support 4 zones in total. This always seemed an unnecessary limitation to me as the protocol supports 7 switched zones and one unswitched zone.

You can get around this by putting a second thermostat on a seperate communication channel and then using some logic to map their zones to zones 5-7 on the master channel, but this still only gives you 7 zones and requires a bit of work.

You can also expand to lots of zones with some rather involved logic, but given the thermostats are no longer available you are probably better off finding an alternate device. Clipsal/Schneider now suggests the SE8000 series which connect to an SHAC via modbus. I have no experience with these though.

 

Thank you for your reply Ashleigh. It sounds like a bridge too far. What a shame about the 4 zone limit and that they are discontinued...perhaps causality?

I guess I can still do it all without the thermostat anyway. I can just have it laid out on a touch screen set up like a normal A/C controller. The relays do all the heavy lifting wrt to fan speed, fan coil/compressor on/off, reverse cycle, and damper control anyway. I can add some logic based on room temps and set points.

it can also be controlled by homebridge and voice commands.

Thank you for your time in replying to my post.

Cheers

Jason