What Is an In-Line Water Heater on a Walk-In Tub?

An in-line water heater is the heater plumbed into the hydro massage loop under an Ella walk-in tub. It maintains, but does not raise, your bath temperature while the hydro pump is running. Sometimes called the inline heater, the hydro heater or the water heater on the jets, it is part of every hydro massage package and works quietly in the background so you stay warm through a long soak.

How It Works

You fill the tub with comfortably hot water from the faucet; your home water heater does the heating. Once the water is 2 inches above the highest jets and you switch on the hydro massage, the pump pulls water through the heater and back out through the jets, and the heater offsets the natural cooling of the bath to hold a steady temperature. It switches on and off with the pump, so there is no heater button and no thermostat to set. It will not warm a bath that was filled with cool water, and it does nothing for the air massage, which has no heater. On tubs with independent foot massage, the heater is attached to the foot massage pump, so running the foot jets is what keeps the water warm on those configurations. Typical ratings on the spec sheets are 6A 650W on the Standard, Zen and Flow, 5.5A 650W on the Elite and Petite, and 9A 1000W on the Ultimate foot loop. Read more in Does the In-Line Water Heater Warm Up My Bath and Will I Get Cold While the Tub Fills or Drains.

Which Ella Models Have It

Every Ella tub with a hydro massage package has an in-line heater, across the Standard and Zen family, the stainless-door tubs, the Ultra, the outward-swing tubs, the two-seat tubs, the Transfer tubs and the LayDown hydro option. Tubs with Hydro plus Independent Foot Massage, such as the Ultimate (Model profile), carry the heater on the foot loop. Air-only and soaking tubs have no hydro pump and no heater. The foot massage layout is explained in Independent Foot Massage.

What to Know as an Owner

Because the heater only maintains temperature, start with a hot fill from a large enough home water heater; see What Size Water Heater Do I Need. Keep bath water at or below 100.4 degrees Fahrenheit. If you find water at the heater unions, the usual cause is an over-tightened or displaced O-ring; the union should be taken apart, the O-ring reseated and the union reassembled, and the heater threads should match the pipe threads. The heater is covered as supporting equipment under the Lifetime Limited Warranty. For a ticket at ellasbubbles.com/support, have your model, serial number, therapy package, whether the hydro pump runs normally, whether the bath cools faster than it used to and a photo of the heater if you can see it through the access panel.

Related Guides

• Does My Ella Tub Include an In-Line Heater? Hydro, Air-Only, Soaker and Clearance Units
• Why Does the Air Massage Blow Cold Air? There Is No Heating Element
• Do Walk-In Tubs Come With Hydrotherapy Jets and Massage Features?
• What is a hydro tub and how does hydro massage work?
• Are there walk-in bathtubs only 28 inches wide for small bathrooms?
• What Is an Air Bath Tub and How Do Air Jets Work?

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