If your sinks run hot but the shower stays lukewarm even with the handle turned all the way, check the shower valve’s temperature limit stop. Moen Posi-Temp and Delta Monitor valves have an adjustable stop behind the handle that caps how far it turns toward hot; set too cool, it keeps the shower lukewarm. Take the handle off, move the stop one notch or tooth toward hot, and test with a thermometer until the water is hot but no hotter than 120°F, or 110°F where your local code sets that limit. If every tap is lukewarm, the problem is the water heater instead.
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The one tool this job needs: a thermometer, so you raise the limit without making the shower scald. Check the Yacumama water thermometer on Amazon
First, Is It the Shower or the Water Heater?
- Only the shower is lukewarm; the sinks are hot: the limit stop in the shower valve is the first suspect. Keep reading.
- Every faucet is lukewarm: Moen notes that with the handle fully turned, the shower matches the temperature set on the water heater. Start with no hot water troubleshooting. On an electric tank, check the elements (water heater element replacement); hot water that runs out fast can be a broken dip tube.
- The shower swings hot and cold, or turns hot when someone flushes a toilet: that points to the valve cartridge, not the limit stop. See shower valve cartridge replacement.
Measure Before You Change Anything
Delta’s method: let the water run until the hot and cold are fully mixed, turn the handle to the hottest position, and hold a thermometer in a plastic tumbler in the stream. Write the number down. You will test again after each adjustment.
How to Adjust a Moen Posi-Temp Limit Stop
These steps follow Moen’s instructions for its Posi-Temp valve.
- Turn off the water supply to the shower, as Moen directs, and cover the drain so no small parts go down it.
- Remove the handle and the handle pieces. Behind them you will see the key stop and the temperature limit stop.
- Check where the stop sits. Moen’s diagram shows the stop position that gives full hot water. If yours is sitting in one of the lower notches, it is limiting the hot side.
- Move it. Pull the temperature limit stop out, rotate it and set it back into a notch on the key stop. Moen’s instruction for making the water cooler is to rotate it clockwise into a lower notch, so to allow more hot water you go the other way, one notch at a time.
- Test before you reassemble. Moen says to put the handle or handle adapter back on without fully reassembling. Turn the water back on, rotate the handle to full hot and check the temperature with a thermometer. Repeat until you reach the temperature you want, not over 120°F (or 110°F where your local code sets that limit), then reinstall the handle.
How to Adjust a Delta Monitor Limit Stop
Delta’s instructions depend on the series:
- Monitor 1300 and 1400 series (the handle controls temperature only): remove the handle. Delta says you may need a 1/8-inch or 3/32-inch hex key or a Phillips screwdriver, depending on the handle. If the water is too cool, rotate the rotational limit stop clockwise. Each tooth changes the maximum temperature by about 6°F.
- Monitor 1700 and 1800 series (the handle controls volume and a knob controls temperature): pry off the temperature knob cover from the side with your fingers or a wooden or plastic tool. If the water is too cool, rotate the limit stop counterclockwise. Each tooth is about 2°F.
Then test the hottest flow again with the thermometer and put the handle or knob back. Delta says to make sure cold water comes from the valve first and that the hottest flow does not exceed the temperature your code allows. On the 1300 and 1400 series, secure the handle screw without overtightening.
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If the Limit Stop Was Already on Full Hot
- Measure a sink. If it is lukewarm too, the water heater is set low or failing; see no hot water troubleshooting.
- If you have a thermostatic mixing valve at the water heater, its setting caps every fixture it feeds.
- If the temperature drifts or the handle feels rough, the cartridge may be worn; see how to replace a shower cartridge.
- Weak flow as well as low heat is a different problem; see low water pressure in the shower.
What You Need
- A thermometer. Moen lists one as the tool for this job. The Yacumama digital water thermometer reads from -58°F to 572°F with ±1.8°F accuracy and is IPX7 waterproof, per the listing; it was shipped by Amazon, new and in stock, when we checked on September 24, 2026.
- A hex key or screwdriver to take the handle off: a 1/8-inch or 3/32-inch hex key or a Phillips screwdriver on Delta handles, per Delta.
When to Call a Licensed Plumber
- You cannot tell the brand or the valve has no adjustable stop you can find.
- The handle or trim will not come off without force.
- Adjusting the stop does not change the temperature, or the water swings between hot and cold.
- You have no experience with shower repairs; Delta itself recommends a licensed plumber in that case.
FAQ
Why is my shower not hot but the sink is?
If the sinks run hot and only the shower is lukewarm with the handle turned all the way, the shower valve’s temperature limit stop is the usual place to look. Moen Posi-Temp and Delta Monitor valves both use an adjustable limit stop behind the handle that sets how far the handle can turn toward hot.
How hot should shower water be?
Moen recommends limiting the maximum temperature from the shower to 120°F or less to prevent scalding. Delta tells you to check against your local plumbing code, which it says is 110°F or 120°F.
Which way do I turn the limit stop on a Delta shower?
It depends on the series. On a Monitor 1300 or 1400 series, if the water is too cool, turn the rotational limit stop clockwise; Delta says each tooth changes the maximum by about 6°F. On a 1700 or 1800 series, turn it counterclockwise; each tooth is about 2°F.
How do I check the shower water temperature?
Let the water run until the hot and cold are fully mixed, turn the handle to the hottest position, and hold a thermometer in a plastic cup in the stream. That is Delta’s method; Moen lists a thermometer as the tool for the job.
Can the water heater make the shower lukewarm?
Yes. Moen says that with the handle fully rotated the shower will match the temperature set on the water heater. If every faucet in the house is lukewarm, the problem is at the water heater, not the shower valve.
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Sources
- Moen: How to Adjust the PosiTemp Temperature Limit Stop
- Delta: How do I set the adjustable rotational limit stop on my bath or shower?
Bottom Line
If the shower stays lukewarm while the sinks run hot, check the limit stop first. Take the handle off (on a Moen, with the water supply off as Moen directs), move the stop one step toward hot (the reverse of Moen’s clockwise cooling direction on a Posi-Temp; clockwise on a Delta 1300/1400; counterclockwise on a Delta 1700/1800), then, with the water supply on, run the shower at full hot and test with a thermometer until it is hot but no hotter than 120°F, or 110°F where your local code sets that limit. If every tap is lukewarm, look at the water heater instead.