72 m², five Daikin air conditioners on a two-pipe system — and still a temperature of its own in every room

The air conditioners here run on a two-pipe system, which cannot heat some rooms while cooling others. One unit is the lead, and its mode limits the rest: while the lead cools, the others may cool, ventilate or dry; while it heats, only heat or ventilate; in fan mode, only ventilate; in dry mode, cool, ventilate or dry.

Five rooms rarely want the same thing. One can call for cooling while the next is already below its setpoint — and at that moment the second room's air conditioner physically cannot heat it. Pass the lead's mode straight through and that unit starts cooling a room that is already too cold.

Every room also needs heating, humidification and blinds. A separate thermostat, humidistat and air conditioner remote in each of five rooms means three or four interfaces on every wall, none of which knows what the others are doing.

The modes are coordinated by a Wiren Board controller. In automatic mode the lead picks heating or cooling from the temperature in its own room, and every other unit chooses within what it is allowed: while the lead cools, a unit cools only if its own room needs cooling and ventilates otherwise; while the lead heats, it heats or ventilates by the same rule. A dry request on a secondary unit while the lead is heating becomes ventilation.

The heat the two-pipe system cannot deliver comes from the heating. The heating valve in each room works independently of the air conditioner modes: it opens when the room falls 1 °C below the setpoint. A room whose air conditioner cannot heat right now still gets warm.

Fan speed follows the deviation, not a button: more than 3 °C from the setpoint means full speed, between 1 and 3 °C an intermediate speed, within a degree the quiet setting. An air conditioner is loud only while it is actually catching up.

The Z35 panel is both the interface and the sensor: its built-in sensors report the room temperature and humidity, so the project contains not a single separate sensor. The setpoint goes from the panel straight to the KLIC-DD v3 gateway of that room's air conditioner, and the gateway's fault flag is shown as an indicator on the same panel.

Humidification closes directly on the bus. The panel's second thermostat takes humidity rather than temperature as its input, from the same built-in sensor: when humidity falls below the setpoint, its two-point output closes a relay on the MAXinBOX 24 and that room's humidifier starts. The controller plays no part in this loop.

The same MAXinBOX 24 carries eight blind drives — 16 outputs for the blinds and 5 for the humidifiers, 21 of 24 in use. Travel time is set per drive, from 64 to 123 seconds, so a position command in per cent means the same on every window. The panel in zone 1.11 runs four drives individually and as two pairs.