What Is the Control Box on a Walk-In Tub?
Updated September 2026
The control box on an Ella walk-in tub is the blue electronic box mounted under the tub, behind the front access panel. Owners often call it the blue box. It receives the air signals sent by the push buttons or the digital keypad and switches power to the pumps, the in-line heater and the lights. Tubs with a heated seat use a master control box. When several functions act up at once, a reset often clears the trouble.
How It Works
The push buttons on the deck are pneumatic. Pressing one sends a puff of air down a small hose to a labeled port on the box, where a relay switches the matching pump or light on or off. The ports are labeled by function: the Water button connects to Pump #1 Airswitch, the Air button to Blower/Pump #2 Airswitch and the Light button to the Light Airswitch. Our push-button air hose guide shows each connection.
A green LED on the box lights whenever power reaches it. On a normal power-up the LED flashes four times and then stays solid green. Some boxes use a standard three-prong 15 amp plug; the larger master boxes use a 20 amp plug with one vertical prong and one horizontal prong. The LED chromatherapy light has its own separate control box and transformer.
Which Ella Models Have It
Every Ella tub with a pump or a light has a control box; a soaking-only tub with no pumps and no lights has no therapy controls for a box to run. Tubs ordered with the heated seat and backrest use a master control box, and two-seat tubs have a heated seat box and keypad for each seat. The box is reached through the front apron or access panel; our service access article explains how access works on each family.
What to Know as an Owner
Leave the equipment compartment uninsulated and reachable. If the tub stops responding, check the green LED, then confirm every air hose is seated at the button and at the box. To reset, disconnect power, label and unplug every tube and connector, restore power, hold the config button through one, two, three and four blinks, then reconnect everything and test each function. The step-by-step reset guide walks through it. Replacement boxes are tested and configured before they ship, so a new box never needs a reset.
For a ticket at ellasbubbles.com/support, have your model and serial number, a photo of the box showing the LED, and a list of which functions fail. The no-power diagnosis article, cord identification guide and control troubleshooting article cover the rest.
Related Guides
- Where Can the Digital Control Be Mounted and How Is It Installed?
- Control Box Configure Button: How Many Blinks, the One-Blink Reset, and the In-Line Heater Box
- Ordering a Replacement Electronic Keypad for Your Walk-In Tub
- Heated Seat and Back Not Warming Up: Checking the Control Box LED and the Button Prongs
- Why does a deck push button do nothing on my walk-in tub?
Common Questions
Why is there no green light on my control box?
How do I reset the control box on my walk-in tub?
Which hose goes to which port on the control box?
Do I need to reset a replacement control box?
Why does my LED chromatherapy light have its own box?
About this guide. Answers in the Ella’s Bubbles Support Center are compiled from real conversations with tub owners, our technicians’ notes and the product documentation, then reviewed by our team. Tub models and options have evolved over the years, so a detail here may differ slightly from your exact tub. If something looks different on yours, send us your serial number and a specialist will confirm it for your model.
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