For most Ella walk-in tubs, we recommend a tank water heater of at least 75 gallons, or a tankless water heater that delivers at least 11 gallons per minute. The larger two-seat and bariatric models call for more hot water: 80 gallons for the Tub4Two and Companion, and 100 gallons for the Big4One, Shak, Big4Two and Escape. These are the figures our support team gives homeowners and installers, and they apply whether you are planning a new installation or checking an existing heater before your tub arrives.

Recommended Tank Heater Size by Model

• 75 gallons: most Ella walk-in tubs, including the single-seat models.
• 80 gallons: Tub4Two and Companion.
• 100 gallons: Big4One, Shak, Big4Two and Escape.

These recommendations assume a heater in good working order at a normal set temperature. If your model is not listed above, 75 gallons is the figure to plan around, and you can always confirm with your Ella dealer or the team at (800) 480-6850. The general sizing guidance, including the factors a plumber weighs, is in What size water heater do I need for my walk-in tub?.

Tankless Water Heaters

A tankless heater can work well with a walk-in tub as long as it can keep pace with the fast-fill faucet. We recommend a tankless unit rated for at least 11 gallons per minute. Any other fixture running at the same time draws from that same supply, so your plumber can confirm the rated output of the unit you have or plan to install and whether it is enough for your home.

Why the Larger Tubs Need More Hot Water

The bigger the tub, the more hot water it takes to reach a comfortable bathing depth. The Big4One, for example, holds 127 gallons unoccupied and roughly 75 to 100 gallons with a bather seated, which is why it carries the 100-gallon recommendation. Capacity for every model is listed in our water capacity guide, and occupied versus unoccupied capacity explains why the volume you actually fill is lower than the printed figure. Ella fast-fill faucets move water quickly, so see fast-fill faucet expectations for what a fill looks like in practice.

Other Factors That Affect the Fill

Heater size is the biggest variable, but it is not the only one. House water pressure, supply pipe size, the distance from the heater to the tub, the heater's set temperature and whether anyone else is drawing hot water during the fill all play a part. A licensed plumber can look at these together and tell you whether your current heater is enough, or whether an upgrade or a dedicated heater for the bathroom makes sense. Ella's Bubbles does not send technicians, so this assessment is done by your local plumber.

How to Check Your Setup Before the Tub Arrives

1. Identify your tub model from your order and look up its capacity in the water capacity guide.
2. Read the capacity label on your tank heater, or the gallons-per-minute rating on a tankless unit.
3. Compare that figure with the recommendation above for your model.
4. Ask your plumber to check water pressure, pipe size and the run from the heater to the tub location.
5. If the heater falls short, discuss an upgrade or a dedicated heater with your plumber before installation day.

If the tub is already installed and the water cools off before the tub is full, Why does my hot water run out before the tub is full? walks through the likely causes.

Common Questions

Still Need Help?

Open a ticket at ellasbubbles.com/support or call (800) 480-6850 and have your model and serial number ready.