Support Center / Therapies & Operation / Does the in-line water heater warm up my bath? What it does and does not do
Back to Therapies & Operation

Does the in-line water heater warm up my bath? What it does and does not do

Updated September 2026

Does the in-line water heater warm up my bath? No. The in-line water heater on Ella hydro massage tubs is designed to maintain your bath temperature, not to raise it. You fill the tub with comfortably hot water from the faucet, and then, whenever the hydro massage pump is running, the in-line heater keeps that water at a consistent, comfortable temperature so you stay warm through your whole soak. It will not warm up a bath that was filled with cool water, and it only operates while the hydro pump is on.

How It Works

In-line Water Heater Maintains Comfortable Water Temperature

As the video explains: when you fill your Ella walk-in tub with the five piece or two piece fast-fill faucet set, you set the temperature at the level that suits you best. When you engage the hydro massage, the in-line water heater works together with the water pump to maintain a consistent warm temperature so you stay warm and comfortable. In practice that means: Watch: Ella's Bubbles: In-line Water Heater Maintains Comfortable Water Temperature with a full transcript.

  1. Fill the tub from the faucet at your preferred temperature. Your home water heater does the heating.
  2. Once the water is 2 inches above the highest jets, turn on the hydro massage. Our water level article explains why that level matters.
  3. The in-line heater switches on and off automatically with the hydro pump. There is no separate heater button and no thermostat to set.
  4. While the hydro massage runs, the heater offsets the natural cooling of the bath and holds the temperature steady.

On tubs equipped with the independent foot massage, the in-line heater is attached to the foot massage pump, so running the foot jets is what keeps the water warm on those configurations. For safety, bath water should be kept at or below 100.4 F.

Ella walk-in tub in-line water heater unit with stainless steel body and white threaded fittings
The in-line water heater is plumbed into the hydro loop under the tub and runs only while the pump runs.

What the In-Line Heater Is Not

  • It is not a water heater for filling. Your household water heater supplies the hot water for the bath. We recommend the largest capacity unit available for your home, and anything under 75 gallons is not recommended. For tankless systems, choose a flow rate of 11 GPM or higher. See what size water heater you need.
  • It is not a heater for the air massage. The air system does not have its own heater. Only the hydro loop is heated.
  • It is not the heated seat and backrest. That optional system warms the seat surfaces with its own button and has nothing to do with the water.
  • It does not run during a still soak. If all pumps are off, the heater is off too. Keeping the hydro massage running is what keeps the heater working.

Which Packages Include It

The in-line heater is included with every hydro massage package. Soaking tubs have no pumps and no heater, and air-only configurations have no heater either, because the air blower simply moves air. Our therapy package inclusions cheat sheet lists what comes with each package.

In-Line Heater Ratings by Model

Every rating below is exactly as printed on the current spec sheets:

ModelHeater rating
Standard, Standard60, Zen, Zen60, Flow6A, 650W
Elite, Petite, Companion, Escape5.5A, 650W
Ultra5.5A
Royal, Deluxe, Front Entry, Shak6A, 650W
Capri, Lounger, Tub4Two, Big4Two6A, 800W
Big4One6A, 750W
Ultimate (heater in the foot and calf hydro loop)9A, 1000W

If Your Bath Still Cools Off Quickly

The most common reason a bath does not stay warm is that it did not start warm enough, usually because the home's water heater ran low while filling. Checking your hot water supply is the best first step. This video walks through how to size your hot water capacity:

Determining Correct Hot Water Supply For A Walk-In Tub
Chapters in this video
  1. 0:00 Hot Water Heater Capacity The video explains the recommended hot water heater capacity for an optimal walk-in tub bathing experience.
  2. 0:37 Finding Tub Water Capacity The video shows how to find the water capacity of Ella's Bubbles walk-in tubs on the website.
  3. 1:04 Dedicated Hot Water Supply The video suggests considering a dedicated hot water supply system for your walk-in tub.
  4. 1:16 Supply Lines And Faucet Sets The video recommends 3/4 inch supply lines and mentions included supply lines with Ella's Fast Fill faucet sets.

As it recommends, check the water capacity of your tub on the Compare Specs page, shown in gallons occupied and unoccupied, and make sure your hot water system can cover the tub plus the other demands in your home. Three quarter inch supply lines with easily accessible shut off valves are recommended, and a dedicated hot water system just for the tub is worth considering for larger models. Your plumber or installer can confirm the right setup for your home. Watch: Ella's Bubbles: Determining Correct Hot Water Supply For A Walk-In Tub with chapters and a full transcript.

If the tub was filled hot and the water still cools quickly with the hydro jets running, or the jets blow noticeably cold water, the heater circuit deserves a look. Open a ticket with your model and serial number so the team can check it; the heater is a replaceable part, and our pump and massage system troubleshooting guide covers the power and connection checks that come first.

Client Testimonial: inline heater keeps temperature
Chapters in this video
  1. 0:00 Why the Customer Chose a Walk-In Tub The interviewer asks the customer what led her to decide on installing an Ella's Bubbles walk-in tub in her home.
  2. 0:47 Safety and Comfort Features The customer discusses the safety aspects of the tub, including the easy entry and comfortable seat, and mentions the therapeutic lights.
  3. 1:21 Favorite Features and Temperature Control The customer shares her favorite features, highlighting the consistent water temperature maintained by the tub's inline heater.
  4. 2:18 Medical Benefits of Hydro Massage The interviewer explains the medical advantages of the hydro massage and air jets, noting their ability to stimulate the immune system.

In this testimonial, a dealer interviews a 93 year old owner who mentions that the in-line heater keeps the water temperature constant during her hydro massage, which is exactly the job it is built for. Watch: Benefits of a Bathroom Walk-In Tub with Door & Seat: Client Testimonial with chapters and a full transcript.

If your air massage blows cool air, that is normal because the air pump has no heating element and draws its air from the space under the tub. See why the air massage blows cold air and there is no heating element for what to expect and how to reduce the cold-air feeling.

Common Questions

The water turns cold halfway through filling. Is the heater broken?
No. The in-line heater runs only with the hydro pump and only maintains temperature; filling temperature comes entirely from your home water heater. A tank that runs low mid-fill is the usual cause, so check its size and recovery.
Is there a heater button or thermostat?
No, there is no separate heater button or thermostat for the in-line water heater on Ella hydro massage tubs. The in-line heater switches on and off automatically with the hydro massage pump. You set your preferred bath temperature at the faucet when filling the tub.
Will it bring the bath up to 104 F?
No, the in-line water heater will not bring the bath up to 104u00b0F. Its design is to maintain the bath temperature you filled the tub with, not to raise it. For safety, Ella's Bubbles advises keeping bath water at or below 100.4u00b0F.
How much power does the heater draw?
The in-line water heater draws about 5.5A to 9A, depending on your specific Ella's Bubbles walk-in tub model. For example, the Elite, Petite, Companion, and Escape models draw 5.5A, while the Ultimate model draws 9A. These ratings are exactly as printed on the current spec sheets for each model.
Is the in-line heater included with all therapy packages?
The in-line heater is included with every hydro massage package from Ella's Bubbles. Soaking tubs, which have no pumps, do not include an in-line heater. Air-only configurations also do not have a heater, as the air blower simply moves air without heating it.
Does the air massage tub have a heater?
No, the air massage tub does not have a heater. The air system on Ella's Bubbles walk-in tubs does not include its own heater. Only the hydro loop, which is part of the hydro massage system, is heated by the in-line water heater.
What temperature should my home water heater be set to?
Ella's Bubbles publishes no recommended setpoint for your home water heater. You control the bath temperature at the faucet exactly as you would with a regular tub. For safety, Ella's Bubbles advises keeping the bath water at or below 100.4u00b0F.
The faucet itself will not give me hot water. Is that the in-line heater?
No, if the faucet itself is not giving you hot water, this is not an issue with the in-line heater. The fill temperature for your bath comes entirely from your home water heater through the faucet. Cold-only or scalding-only water from the faucet points to a problem with the faucet or its thermostatic control valve, not the in-line heater.
My in-line heater is leaking. Can it be replaced?
Yes, if your in-line heater is leaking, it can be replaced. To address this, you should first switch the tub's circuit off for safety. Then, open a ticket with your model and serial number, along with a photo of the leak, so the Ella's Bubbles team can identify the correct replacement heater for your specific tub.
Can heat be added to a tub that does not have it?
The in-line heater is an integral part of the hydro massage package and is fitted at the factory. It is not a removable option. If you are considering adding heat to an installed tub that does not currently have it, please ask the Ella's Bubbles team with your model and serial number before assuming it can be added.
Can I leave the heater off my order to keep things simpler?
No. Every hydro massage package includes the in line heater and ozone sterilization as standard; the heater is not a removable option. It runs only while the hydro pump runs and holds the temperature you filled with; it does not reheat cold water.
My new in line heater has a different plug than the one on my old tub. Is that right?
Yes. Heater ratings differ by model, and a higher rated heater ships with a regular plug while a lower rated one may use a piggyback plug. Either stays within the dedicated hydro circuit; the higher rating simply holds heat longer. Check the sticker on the cord and the electrical diagram for your package if your electrician has questions.

Still need help? Open a ticket at ellasbubbles.com/support or call (800) 480-6850 and our team will be glad to walk through it with you.

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.

Did this solve your question?

If not, open a ticket and our team will pick it up from here.

Open a Support Ticket