I’m planning a hydronic (water-based) underfloor heating setup for a new house extension and I’d like to control it entirely through my own Home Assistant Zigbee network (via Zigbee2MQTT), without relying on any manufacturer’s own gateway/app/cloud.
My planned setup for each of the 6-8 zones:
A generic Zigbee DIN-rail relay (looking at the SONOFF BASIC-ZB1GSP) mounted next to the manifold, paired directly to my own Zigbee coordinator
A standard 230V NC thermoelectric actuator (M30x1.5) on the manifold - considering Danfoss Thermot 088H3220 or a Salus version with manual override
A Zigbee wall thermostat/sensor in each room (looking at Moes water UFH thermostats) feeding a generic_thermostat helper in HA, which drives the relay
I understand the electrical/technical side of this fairly well at this point, but I haven’t been able to find real photos of anyone’s actual manifold cabinet wired up this way (generic Zigbee relay + generic actuators, no all-in-one branded control box like ENGO/Salus).
Has anyone here built something like this? I’d love to see photos of your manifold/cabinet setup, and hear about any lessons learned - especially around wiring, DIN rail layout, or anything you’d do differently.
An option to consider: If you are running wires for underfloor heating on a new build, run an extra twisted pair for switching and sensing too, and you may not need the vaguaries of ZigBee.
RS485/Modbus control is robust, used widely in the HVAC industry, is often daisy chained for multiple devices, and USB adaptors on the HomeAssistant server end are fairly cheap. Hint: Don’t forget the 120ohm termination resistors, one on each end ONLY.
You will find RS485/ModBus thermostats, valves, relays/contactors are fairly generic and easily integrated into HomeAssistant.
Why not ZigBee? No batteries. No monthly HomeAssistant updates that nuke your devices and need futzing, it just works as it is hard wired. No firmware updates needed.
Have you considered geothermal heating/cooling, taking advantage of the constant ground temperature about 2 metres down is around 18°C all year around? Depending on your location and cost of electricity, it may be cheaper for long term running costs, amortised over 15-25 years. No thermostats required - the temperature is comfortable all year round. Worth looking into, as you are running heating pipes under the floor anyway, and geothermal provides year round constant temperature with only minimal costs to circulate, not heat/cool. Yes you will have to dig/drill/trench down and backfill a lot of earth, but look at a ten year costing figure for different options may clarify things if the upfront costs frighten, like they do with underfloor heating as well. Your break even point may be as low as five years depending on your location, and the geothermal life span is double that of electric wires. Solar power, combined with batteries may change the figures too, as will an efficient heat pump if you live in very harsh climes, or have teenagers that love to set the temperature to ‘beach’ mid-winter!
Just options to consider before you take the plunge.