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Jacuzzi J235 (EW11A or ESP32)

This guide sets up spa2mqtt for a Jacuzzi J235: a J-200 series tub from 2018 with the encrypted Balboa-family control board. spa2mqtt reads the board's RS485 bus through an RS485-to-TCP adapter such as the Elfin EW11A, or through an ESP32 running the ESPHome component. The definition ID is jacuzzi_j235. It is the default, so most settings on this page are the defaults.

Tested on the project's own tub

Every sensor was checked against labelled captures from the project's own J235. Transmit runs on that tub through the MQTT bridge and an EW11A (November 2026): the board granted the bridge channel 0x11, and the buttons, Temperature Set Control and the switches act at the topside. Start receive-only on a new install, and watch the topside for the first commands.

What is supported

Each row has the evidence status from the definition. Confirmed means a labelled capture shows the change at the topside and the same change in the bytes. Hypothesis means a pattern in the data, or a name from another project, that no capture confirms. The wire protocol has the bytes.

Read

Entity Status Notes
Current Water Temperature Confirmed °C, in 0.5 °C steps
Target Water Temperature Confirmed °C, in 0.5 °C steps
Pump 1 Speed Confirmed off, low or high
Main Pump Status Confirmed Pump 1 on high: the jets
Circulation Pump Status Confirmed Pump 1 running at any speed. The J235 has no separate circulation pump: it heats and filters on pump 1 low
Secondary Pump Status Confirmed Pump 2. Single speed
Heater Active Confirmed
Light Mode Confirmed off, a colour name, blend or blend paused. MQTT bridge only
Filter Change Days, Water Change Days, UV Lamp Days Confirmed The topside menu's FC, H2O and UV countdowns, in days. Diagnostics
Manual Circulation Call Hypothesis Never seen set on this tub
Set Mode Active, Display State, Secondary Value Raw Mixed Diagnostics, disabled by default

Control

All controls are unavailable until you enable transmit.

Entity What it does
Temperature Increment, Temperature Decrement One press of Temp up or Temp down. The first press only opens the set screen
Temperature Set Control Presses Temp up or down until the setpoint matches. Range 20 to 40 °C, step 0.5
Pump 1 Button, Pump 2 Button, Light Button One press of that topside button. Pump 1 steps off, low, high, off
Pump 1 (switch) The jets. Presses Pump 1 until pump 1 is on high, or off. MQTT bridge only
Pump 1 Low (switch) Pump 1 low speed. Its "off" is pump 1 fully off, so from low it steps through high to off. MQTT bridge only
Pump 2 (switch) Presses Pump 2 when it is not already in the state you chose. MQTT bridge only
Light (switch) Presses Light until the light is on or off, about 7.5 s between presses. MQTT bridge only

The button codes (0x01, 0x02, 0x04, 0x05, 0x12) were confirmed from the topside's own presses in a capture. The bridge sends the same codes.

Not supported

  • Light colour, brightness and blend as direct controls. The light has one button: see Known limits.
  • Clock setting, filter cycles, heat mode, ClearRay and the menu. The maintenance countdowns are read only: reset them at the topside.
  • Fahrenheit. The board gives no unit flag, and every capture is in °C. The definition is Celsius only.

Hardware path

The bridge and the ESP32 both connect to the RS485 header on the control board. The header is meant for a second topside panel and is usually free. It carries 12 V, 0 V, A and B. Isolate the spa at its breaker before you open the equipment bay. Read Safety first.

Item Value
Bus RS485, 115200 baud, 8N1
EW11A mode TCP server, port 8899, transparent
ESP32 Any ESP32 with a 3.3 V RS485 transceiver. See Hardware and wiring
Bus address the bridge sends from A channel the board gives it on the first command. Set at run time, not by the definition

Connect A to A and B to B. If no status frames arrive and the serial settings are right, swap A and B: a swap does no damage. Power the adapter or the ESP32 from its own supply unless you know the rating of the header's 12 V.

The EW11A accepts one TCP client at a time. Stop the v1 bridge, a monitor or any other tool before you start spa2mqtt. The v1 bridge must be stopped in any case: it claims a bus channel at start-up.

Install with Docker Compose

Follow Install with Docker Compose. The defaults in .env.example are for this tub. Set the addresses:

SPA_IP=192.168.1.100
SPA_PORT=8899
SPA_DEFINITION=jacuzzi_j235
SPA_TRANSMIT=false
MQTT_BROKER=192.168.1.7
MQTT_PORT=1883
MQTT_USERNAME=
MQTT_PASSWORD=

Install with Portainer on Home Assistant OS

Follow Install with Portainer, method A, with the stack file deploy/portainer-stack.yml and these variables:

Variable Value
SPA_IP EW11A address, for example 192.168.1.100
SPA_PORT 8899, the default
SPA_DEFINITION jacuzzi_j235, the default
SPA_TRANSMIT false
MQTT_BROKER Broker address. For the Mosquitto add-on, use the Home Assistant host's LAN address: core-mosquitto does not resolve from a Portainer stack
MQTT_PORT 1883
MQTT_USERNAME, MQTT_PASSWORD Broker login, if the broker needs one
LOG_LEVEL INFO

SPA_IP and MQTT_BROKER are required, and the stack refuses to deploy without them.

Install with ESPHome

Follow ESPHome: Hardware and wiring, then Build and flash. The package esphome/packages/jacuzzi_j235.yaml lists every J235 entity the component supports.

The component decodes the status frame only. It has no Light Mode sensor and none of the switches. The buttons and Temperature Set Control are the same.

Upgrade from the v1 bridge

Version 2 replaces the v1 bridge in place. It keeps the device (185569045), the unique_ids and the discovery topics, so every entity keeps its ID and history. Your v1 config.yml and VARIANT_DEFINITION still work. Two changes matter:

  • Buttons and Temperature Set Control are unavailable until you enable transmit. v1 transmitted by default.
  • Main Pump Status is pump 1 on high. Circulation Pump Status is pump 1 at any speed.

See Upgrade from v1 for the full list.

Verify, receive-only first

With transmit off, the bridge and the ESP32 never write to the bus.

  1. Run the read-only monitor once (Getting started). The checksum error count stays at or near zero. A high count means a wrong baud rate or swapped A and B.
  2. In Home Assistant, open Settings > Devices & services. A device named Jacuzzi J235 appears under MQTT, or under ESPHome for the component. The controls show as unavailable. That is expected.

  3. Compare with the topside:

    Check How
    Current Water Temperature Same number as the topside display
    Target Water Temperature Press Temp up twice at the topside: the first press opens the set screen, the second adds 0.5 °C. Then step back
    Pump 1 Speed Press the pump 1 button three times: low, high, off
    Pump 2 Press the pump 2 button on and off
    Heater Active Raise the setpoint above the water temperature. Pump 1 starts on low, then the heater follows about a minute later
    Light Mode Press the light button. MQTT bridge only
    Filter Change Days, Water Change Days, UV Lamp Days The FC, H2O and UV values in the topside menu

Enable transmit

Read Safety first.

First commands on your tub

The channel claim works on the project's J235 with the MQTT bridge. Your board, adapter or ESP32 wiring may differ. Have someone at the topside for the first commands.

What the bridge or the ESP32 sends:

  1. At start-up, nothing.
  2. On the first command, a channel request. The J235's only polled channel (0x10) is the topside panel, and it answers every poll, so there is no free channel to reuse. spa2mqtt asks the board for a new one when the board offers it, about once a second, and acknowledges the answer.
  3. Then one button press each time the board polls that channel. When nothing is queued, it stays silent.
  4. If another device answers on the same channel, spa2mqtt goes back to listening.

For the MQTT bridge, set SPA_TRANSMIT=true and recreate the container or update the stack. The log shows TRANSMIT ENABLED. For ESPHome, set transmit: true in the spa_bus: block and install the firmware: the Bus State sensor shows claiming, requested, then ready (0x..) on the first command.

Test in this order, one command at a time, and watch the topside after each:

  1. Pump 2 Button, twice: on, then off.
  2. Light Button, then wait ten seconds and press it again to turn the light off.
  3. Pump 1 Button, three times: low, high, off.
  4. Temperature Increment, twice, then Temperature Decrement once. The setpoint rises 0.5 °C and falls back.
  5. Temperature Set Control, 0.5 °C up, then back.
  6. The switches, last.

To stop, set transmit off again. If the topside shows an error, isolate the spa at the breaker and wait before you switch it on again.

Send captures back

A capture of something new on this tub helps, in particular a session with commands and the menu. spa2mqtt capture is read-only and keeps only the frames that changed:

docker run --rm -it ghcr.io/srleach/spa2mqtt:2 spa2mqtt capture 192.168.1.100 -o j235.log

For a session with labels, use tools/capture.py. Stop the bridge first: the EW11A accepts one client. See Monitor and capture for both, and Contribute a capture to share the file.

Known limits

  • Celsius only. The board's status gives no unit flag. Keep the topside in °C.
  • The first temperature press only opens the set screen. Temperature Increment and Temperature Decrement behave like the topside. Temperature Set Control accounts for it.
  • Pump 1 Low may not turn off. The board runs pump 1 low by itself to heat or filter. While it does, pressing pump 1 cannot reach off, and the switch gives up after a fixed number of presses.
  • The light has one button. A press within a few seconds of the last one steps the colour. A press after a pause turns the light off. The Light switch waits about 7.5 s between presses for that reason. There is no direct colour or brightness command.
  • ESPHome has no lights frame. Light Mode and the switches are MQTT bridge only.

Open questions that a capture or a test at the tub would answer:

  1. Where are the filter cycle settings and the heat mode? A capture while they are changed at the topside would settle it.
  2. What does Manual Circulation Call show, if anything?
  3. What are the button codes for ClearRay and the menu on this tub?

The wire protocol lists the unknown bytes.