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What Is a Heated Seat and Backrest on a Walk-In Tub?

Updated September 2026

The heated seat and backrest is an optional 4A radiant surface heating system built into the seat and backrest of an Ella walk-in tub. Controlled by its own small keypad, it warms the surfaces you sit and lean against so the tub feels cozy while it fills and after it drains, and it shuts itself off after 20 minutes. Owners also call it the seat heater or, from the invoice code, the HSB. It is completely separate from the in-line water heater that runs with the hydro jets.

How It Works

Radiant heater pads are sealed into the seat and backrest and driven by a heat box under the tub. Press the keypad once to turn the seat on and again to turn it off. For the best first touch, switch it on 10 to 15 minutes before you enter so the surfaces have time to warm while the tub fills. The automatic shutoff after 20 minutes is by design, not a fault; one more press restarts it. Because it heats surfaces rather than water, it works whether the tub is empty or full. The system uses less energy than a light bulb, is hermetically sealed and splash resistant, and is made in the USA. Tubs with a heated seat use a master control box, and the heated seat and backrest article shows the keypad in use.

Heated seat and backrest for Ella walk-in bathtubs
The heated seat and backrest warms the surfaces you sit and lean against, empty or full.

Which Ella Models Have It

The heated seat and backrest is optional on most seated Ella models and is not offered on the LayDown tubs. On the Standard and Zen platform, the manual page for it is stamped Optional, not included, so check your order to see whether it was added. Two-seat tubs carry a heated seat box and keypad for each seat. It can be added to any standard order, while clearance units are configured as listed and are never modified; the clearance tubs article and customization options explain the difference. On your paperwork the option appears as HSB, decoded in the invoice and part codes decoder.

What to Know as an Owner

The heated seat does not warm the bath water. Fill hot from the faucet and let the in-line heater hold the temperature during hydro massage; the seat takes care of the surfaces. A soaking tub whose only electrical item is the heated seat needs a 15A/120V line. On jetted tubs the heater pads are fed through the control box, and no published schematic adds a dedicated line for the heated seat; the number of dedicated lines follows the massage package. If the seat feels cold, confirm the keypad responds, that the seat has not simply reached its 20-minute shutoff, and that the tub has power.

For a ticket at ellasbubbles.com/support, have your model and serial number, confirmation that HSB is on your order, whether the keypad light responds, and on a two-seat tub which seat is cold. If you wonder whether you will feel chilly while the tub fills, this video article answers the question owners ask most.

Common Questions

Why does my heated seat turn off after 20 minutes?
The 20-minute automatic shutoff for the heated seat and backrest is by design, not a fault, and is built into the 4A radiant surface heating system. This automatic shutoff is a normal function of the heated seat. To restart the heated seat, simply press its small keypad once more, and the surfaces will begin to warm again.
Does the heated seat warm the water?
No, the heated seat and backrest does not warm the bath water in your Ella walk-in tub. The heated seat, also known as HSB, is an optional 4A radiant surface heating system that warms only the seat and backrest surfaces you sit and lean against. The in-line water heater, which is a separate component that runs with the hydro jets, is responsible for maintaining the water temperature you filled the tub with from the faucet.
Can I add a heated seat to my order?
Yes, the heated seat and backrest (HSB) can be added to any standard order for most seated Ella walk-in tub models. This optional 4A radiant surface heating system is not offered on LayDown tubs. You should ask your Ella dealer or the support team to add the heated seat option before your tub is built, as clearance units cannot be modified.
Can a clearance tub get a heated seat?
No, a heated seat and backrest cannot be added to a clearance tub. Clearance units are configured as listed and are never modified after they are built. If the heated seat and backrest (HSB) is an important feature for you, you should choose a standard order for an Ella walk-in tub and add the option there.
What does HSB mean on my invoice?
HSB is the invoice code for the optional Heated Seat and Backrest, which is a 4A radiant surface heating system. Seeing HSB on your order paperwork confirms that your Ella walk-in tub was built with the heater pads sealed into the seat and backrest, the heat box located under the tub, and the small keypad for control.

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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