My house contains 3 showers. Two of them warm up to where it's comfortably warm and one just warms up to a point where I don't freeze. Even if the shower is on the highest setting it still is not warm enough. What could be the problem?

  • 2
    Does the sink in the problem bathroom get hot?
    – Steven
    Jan 12, 2014 at 15:41
  • Is the shower at the end of a very long pipe run?
    – bib
    Jan 12, 2014 at 22:38

2 Answers 2


It is likely a defective shower valve, allowing too much cold water to mix with the hot. If the showers are all the same brand and model you could make a swap and verify this suspicion.

It could also be a pipe issue. If there's a nearby sink which might share plumbing, run the hot for 1 minute into a bucket, run the cold for one minute into a bucket, and compare the ratio. Now do the same at a "good" shower. This might show the same pattern of differential flow.


Check that any valves in the line are fully open.

While it may be the shower valve, it could also be a restriction in the pipe itself - if not a partially closed valve, it's a lot harder to find. I had a mystery "hot water to tub" problem that eventually turned out (as I worked my way back from the tub disassembling pipes) to be a copper elbow almost, but not quite, completely plugged with solder.

So, 7 years later, I happened to have camera and the fitting in question from my junk (perhaps "plumbing trophies") box and recall that I want to show it. Trigger warning "terrible plumbing."

Copper pipe elbow plugged with solder - image by me

The little gap at the bottom of this picture was the only passage for water in this fitting.

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