Shower won't get hot, or gets too hot

When the sinks have hot water but the shower does not, or the shower runs hotter than it should, the cause is almost always in the shower valve: a limit stop, a stop that was left partly closed, or a stuck cartridge. Four questions narrow it down.

Also searched as: no hot water in shower but hot water in sink, no hot water in shower only, shower too hot on coldest setting, shower not hot enough.

Before you start. Turn the water off before you remove a shower handle, and check the hottest setting with a thermometer. CPSC recommends 120F; at that temperature a five-minute exposure can still cause third-degree burns.

A hand turning a single-lever shower handle while the shower runs

Every question and answer on this page, in order

Question 1: Is the hot water fine at the kitchen or bathroom sinks?

Run the hot tap at a nearby sink for a minute.

Yes, the sinks get hot: go to question 2
No, the sinks are cold or lukewarm too: Likely cause: the water heater, not the shower

Question 2: What is wrong at the shower?

Not hot enough, even turned all the way to hot: go to question 3
Too hot when turned up to full hot: Likely cause: the limit stop is set too high
Still hot even at the coldest setting: Likely cause: a stuck or worn cartridge

Question 3: Did this start right after a repair, or after the water was shut off?

Think back: a new cartridge, a plumber's visit, or the main being closed and reopened.

Yes, right after: Likely cause: a stop that was not fully reopened
No, it came on gradually or out of nowhere: go to question 4

Question 4: Does the handle turn all the way to the full-hot position?

On Moen single-handle valves, Moen describes full hot as the 9 o'clock position. If the handle hits a stop well short of that, a limit stop is holding it back.

No, it stops early: Likely cause: the temperature limit stop is set too low
Yes, but the water is still only warm: Likely cause: a stuck or worn cartridge

Possible results

Need the words for the phone call? Build a what-to-tell-the-plumber checklist, or read when to call a plumber.