Mechanical water distributors

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A mechanical water distributor splits one water supply into several outlets and steps to the next outlet each time the water is pulsed off and on again. There is no electronics and no wiring per outlet — the pressure surge itself advances an internal wheel. The best-known consumer example is the Gardena Water Distributor; the professional equivalent is an indexing valve such as K-Rain or FIMCO.

Smart Irrigation drives one inlet valve (or pump) and waters each of the distributor's outlets in turn, so a handful of zones can share a single supply line and a single controllable valve. Because the device has no position feedback — it cannot tell you which outlet is currently open — Smart Irrigation tracks the position itself, counting each advance. Getting that tracking right is what most of this page is about.

Experimental. This is a new feature that could not be fully hardware-tested before release. Enable it, but watch the first days of use closely and keep the device's manual override (its selector knob) within reach. It is opt-in and you can switch it back off at any time without losing data — see Enabling it.

Enabling it {#enabling-it}

The distributor is an opt-in feature and is off by default. Turn it on under Setup → Experimental → Mechanical water distributors (see Experimental). Enabling it reveals two things that stay hidden otherwise:

• a new Distributors tab under Setup, where you create and commission distributors, and
• a Water distributor field on each zone's settings, where you assign that zone to an outlet.

Turn the toggle back off and both disappear again; any distributors and zone assignments you already made are kept, not deleted.

Creating a distributor

On the Distributors tab, add a distributor, give it a name, and choose how its inlet is opened and closed:

• Classic — Home Assistant opens and closes an inlet switch/valve/input_boolean entity directly. Set the Inlet valve / switch to that entity. Each advance is a timed open-then-close pulse.
• Self-closing service — a device that closes itself after each pulse (for example a battery valve driven by a script). You provide a Run script (and optionally a Stop script); Smart Irrigation calls the run script to open the inlet for the configured time. Here the Inlet valve / switch field is optional and watch-only — it is read to keep the tracked position in sync (see Watching the inlet), never actuated.

Then set the pulse duration and its unit (seconds or minutes) — how long the inlet stays open to water an outlet before advancing. Give the distributor a supply with enough pressure and flow to actually step the wheel (see Troubleshooting).

Assigning zones to outlets

A distributor is only useful once zones are mapped onto its outlets. On a zone's settings, the Water distributor selector assigns that zone to this distributor. The distributor's outlets are numbered and arranged on the Distributors tab as a contiguous 1…n map; the distributor page flags any gaps in that mapping.

A zone assigned to a distributor is a member zone: it is watered through its outlet, so its own linked valve and its own schedule are managed by the distributor rather than run independently. A member zone therefore does not need its own valve entity.

An outlet with no mapped zone is not watered — the distributor passes it with a short skip pulse (just long enough to advance the wheel) and moves on to the next mapped outlet.

Commissioning & position tracking

Because the outlets are blind, Smart Irrigation infers the position instead of reading it. An advance is counted on the inlet valve's off-edge — every time the water is switched off, the internal wheel is assumed to have stepped by one. From a known starting outlet, counting off-edges keeps the tracked position aligned with the hardware.

To establish that known starting point and confirm the mapping, the Distributors tab gives you:

• Test run — waters each mapped outlet for about 30 seconds in order, so you can stand at the distributor, watch it step, and read off how long a pause it needs between outlets.
• Set current outlet — re-anchors the tracked position to the outlet you tell it. Use this after you have turned the device by hand. It asks for confirmation first, because it marks the distributor as synced.
• Confirm commissioning — arms the distributor for automatic cycles. Until you confirm, automatic watering through the distributor is held back.

If the tracked position ever becomes ambiguous — for example after an unexpected pulse or an interrupted cycle — the distributor is marked uncertain and will not run automatically until you re-sync it (test run, set the current outlet, confirm).

Advance pause & skip pulses

Two timings control how the distributor steps:

• The advance pause is the gap between finishing one outlet and starting the next. It must be long enough for the device to physically complete its step; the backend enforces a minimum of 10 seconds. The test run helps you find the right value for your device.
• The skip pulse is the short on/off used to pass an unmapped outlet without watering it. It also has a 10-second floor.

Master valve / pump coordination

If you use a master valve or pump, Smart Irrigation switches it for the distributor's cycle. Two interactions are worth knowing:

• With master off after each zone under sequential or rotating sequencing, the pump is switched per outlet, so expect it to cycle between every outlet of the distributor.
• A distributor feeds one outlet at a time. So even under parallel sequencing — where several ordinary zones open at once — a distributor's mapped zones still water in sequence. Plan the supply draw accordingly.

Watching the inlet for foreign pulses

The inlet may sometimes be opened outside a Smart Irrigation run — a manual turn, a Home Assistant automation, or your own script. If the tracked position is to stay correct, Smart Irrigation needs to know how to react. The optional inlet-watch does this, with three watch modes:

• Count it — treat the foreign pulse as a real advance and step the tracked position with it.
• Warn — mark the position uncertain (re-sync required) rather than guessing. This is the safe choice when you are not sure a foreign pulse actually stepped the wheel.
• Ignore — do nothing.

Only pulses that Home Assistant can actually see are detected. A purely mechanical turn of the knob, with no entity change reported to Home Assistant, stays invisible — which is exactly why Set current outlet exists.

Optional flow sensor

If you assign the distributor's shared inlet flow meter, each outlet's delivered volume is measured and credited to the zone's bucket instead of the time-based estimate. And where the inlet can be stopped mid-pulse — a classic inlet valve, or a self-closing device with a stop script — an outlet can also stop early once it has delivered its target volume.

Caveat: this flow-metering path is rate-only and, unlike the rest of the feature, could not be hardware-tested at all. Treat it as the least-proven part of an already-experimental feature: enable it if you have a flow sensor and want to try it, but keep an eye on the delivered volumes at first.

Troubleshooting & tips

• Give it pressure and flow. A mechanical distributor needs a firm surge to advance reliably — aim for at least 1 bar of pressure and 20 l/h of flow at the inlet. Too weak a pulse and the wheel may not step, which desynchronises the tracked position.
• Re-sync after turning it by hand. If you move the device manually, use Set current outlet afterwards so the tracked position matches reality.
• "Uncertain" means the position may be wrong. Clear it by re-syncing: run the test run, set the current outlet to where the device actually is, and confirm commissioning.
• Parallel sequencing still waters distributor zones in turn. The distributor can only feed one outlet at a time, so its zones never water simultaneously even when parallel sequencing is on.

Main page: Configuration
Previous: Experimental
Next: Usage