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Hand Sprayer Runs Hot but the Tub Spout Is Only Lukewarm: What to Check

Updated September 2026

▶Glossary9
  1. Why the Two Outlets Can Behave Differently
  2. Checks to Make
  3. If the Diverter Is the Cause
  4. If Nothing at the Tub Is Hot
  5. What to Send the Team
  6. Related Guides
  7. Related Videos
  8. Common Questions
  9. Still Need Help?

When the hand sprayer delivers hot water but the tub spout runs only lukewarm, hot water is clearly reaching the faucet, so the supply shutoffs are not the problem. The difference is created after the water leaves the hot valve. The team looks at three things: whether anything was added between the hot valve and the diverter, whether the diverter itself is at fault, and whether your water heater can keep up with the spout's much higher flow rate. Homes with a tankless water heater deserve a close look at that last point.

Why the Two Outlets Can Behave Differently

The hand sprayer passes a small amount of water. The spout on an Ella fast-fill faucet is built to fill the tub quickly and flows far more, as described in what a fast-fill faucet is. A tank water heater supplies stored hot water at any flow rate. A tankless heater has to heat water as it passes through, so if the spout draws more than the heater can warm, the outlet temperature drops even though the sprayer, at its lower flow, comes out hot. The general guidance for a tankless heater feeding a walk-in tub is a rating of 11 gallons per minute or more.

Checks to Make

  1. Make sure the diverter is fully switched to the spout position. How the diverter works is covered in what a hand shower diverter is.
  2. Look between the hot valve and the diverter. Open the access panel and check whether anything was added there during installation, such as an extra valve or fitting. Anything in that run affects only the hot side.
  3. Note your water heater type and rating. If it is tankless, compare its gallons per minute rating with the 11 gallons per minute guidance and with the flow of your faucet.
  4. Find out whether your faucet includes a thermostatic valve. Not every faucet configuration has one. If yours does, its set point and the condition of the cartridge come into play. If it does not, hot and cold mix at the handles and the diverter is the more likely cause.
  5. Test the sprayer and spout separately. They cannot run at the same time, so compare each on its own at full hot and note the difference.

If the Diverter Is the Cause

A diverter that does not switch cleanly, sticks, or sends water out of the wrong outlet is a replaceable part. The symptoms and the replacement process are in water comes out of the wrong outlet or will not switch back. If the sprayer itself has weak flow rather than the spout, see why the hand shower has no pressure.

If Nothing at the Tub Is Hot

This article covers the case where the sprayer is hot. If neither outlet gets hot while the sinks do, the cause is usually upstream, and no hot water at the tub when the sinks have hot water is the article to follow instead.

What to Send the Team

Open a ticket with your model and serial number, the type and rating of your water heater, which faucet you have, photos of the plumbing behind the access panel and a short description of the symptom. Technical support reviews the configuration and calls back with the fix, which may be an adjustment to the thermostatic valve, a cartridge cleaning, a diverter replacement shipped under the parts warranty, or a change your plumber makes to the hot water supply. If the faucet set itself needs changing, replacing your faucet set, valves or hand mixer explains the options.

Chapters in this video
  1. 0:00 Adjusting the TCV Valve The video demonstrates how to remove the set screw cover and loosen the set screw to access the temperature control valve.
  2. 0:35 Setting Hotter Water Temperature The video shows how to internally set the TCV for hotter water by adjusting the handle on the brass fitting.
  3. 0:56 Finalizing the Temperature Adjustment The video instructs viewers to ensure the anti-scald button is set correctly, then tighten the set screw and replace its cover.

Watch: Ella's Bubbles: TCV Valve Temperature Adjustment with chapters and a full transcript.

Chapters in this video
  1. 0:00 Remove Handle And Collar The technician removes the colored cap, loosens the bolt with an Allen wrench, and lifts off the handle, then removes the plastic collar.
  2. 0:19 Remove And Clean Cartridge The technician uses a socket wrench to loosen and remove the cartridge, then checks for debris and cleans it with a soft brush.
  3. 0:37 Replace Cartridge And Collar The technician replaces the cartridge, tightening it without over-torquing, and then replaces the plastic collar.
  4. 0:51 Reattach Handle And Cap The technician puts the handle back on in the correct position, tightens the Allen bolt firmly, and replaces the colored cap.

Watch: Ella's Bubbles: Cartridge Replacement 5 Piece with chapters and a full transcript.

Common Questions

Why is the hand sprayer hot when the spout is lukewarm?
The sprayer uses far less water than the spout. If your heater, especially a tankless one, cannot heat water fast enough for the spout's high flow, the spout runs cooler while the low-flow sprayer stays hot. A fitting added between the hot valve and the diverter, or a diverter fault, can produce the same result.
Does my tankless water heater need to be replaced?
Not necessarily. Compare its gallons per minute rating with the faucet's flow. The general guidance for a walk-in tub is a tankless heater rated at 11 gallons per minute or more. A plumber can confirm whether your heater can keep up at the spout's flow rate.
Should I clean the thermostatic cartridge to fix this?
Only if your faucet actually has a thermostatic valve, since not every faucet configuration includes one. If yours does not, the mixing happens at the handles, and the diverter is the more likely cause. The team can confirm from your model and serial number.
Is a faulty diverter covered under the warranty?
Ella faucet parts, including the diverter, fall under the lifetime parts warranty for the original owner, while non-Ella faucets carry only their manufacturer's warranty. Once the team confirms the diverter is the cause, the replacement ships to you and a local licensed plumber installs it.

Still Need Help?

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

Related guides

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