I don't have the equipment details on hand but could probably get them if needed. It's a pretty standard boiler + hot water heater + pump set up.

Often the hot water coming out of the shower faucet is... not hot, to say the least, while sinks can get hot enough to scald.

Why is it that the shower is not providing the full range of heated water that is provided elsewhere?

I end up having to leave the shower running for 20 minutes or so to get the room warm and the water slightly warmer though it still never really gets that hot the vast majority of the time.

Is there anything I can do to increase the performance of the hot water heater so it provides hot water on demand? Again this really only affects the shower most of the time.

  • If you shutoff the hot water to the house and turn the shower to its hottest setting, does water still come out? Could the pipes to the shower be running along an exterior wall or other unheated space?
    – BMitch
    Commented Mar 6, 2013 at 20:15
  • @BMitch - For a while (hot water and then cold after that), yes, it it would come from the storage tank I presume (I'm not actually totally sure if its a storage tank but it could be). It is entirely possible that they are running along the exterior wall and are also located in a colder basement (non-heated).
    – Enigma
    Commented Mar 6, 2013 at 20:25
  • But after the pressure equalizes from the tank, does the water stop, or does it continue to flow cold?
    – BMitch
    Commented Mar 6, 2013 at 20:59
  • @BMitch - I'm actually not certain. At most I've only ever turned off the emergency boiler switch and water continued to come out until cold (I think it was getting colder anyways). I'll have to try shutting off the hot water.
    – Enigma
    Commented Mar 6, 2013 at 21:05
  • See also: diy.stackexchange.com/questions/281/…
    – BMitch
    Commented Mar 6, 2013 at 21:32

1 Answer 1


I had this problem once. Is the water flow in your shower controlled by a single knob? If so, then there is an adjustment thingy inside the faucet knob that controls the ratio of hot to cold water. Take the knob off by prying lose the center plastic cap and removing the screw that holds it on. There will be a plastic piece underneath that you can pull out, rotate a little bit toward the hot side, and then push back in. You may have to experiment a little bit to get it where you want it.

Now, it's been a little while since I did this, and I'm pretty sure I didn't have to turn off the water to tear down the faucet to that point, but I just can't remember for sure, so I guess you should turn off the hot and cold water supplying the shower before you take it apart. You can probably find an exploded diagram of your particular faucet online if you can still read the manufacturer's name on it.

This may not fix your problem, but it's a good first step to check before you get too involved with water heaters and pipes just on the principle that it's a 5 minute job and it's free.

  • Yes it's controlled by a single knob. I am stuck at how to get the knob off. I uncapped the screw cover and took the screw out but unless it's really stuck on there, it still seems pretty much attached. There doesn't seem to be anything I can pull out at the moment so my thought it that it is behind the knob I can't get off.
    – Enigma
    Commented Mar 8, 2013 at 3:35
  • It seems I broke it... diy.stackexchange.com/q/25822/11444
    – Enigma
    Commented Mar 8, 2013 at 4:14
  • 1
    I posted a link in your other topic with instructions on how to fix your valve, if it's fixable at this point. By the way, this valve uses a different system than the plastic "adjustment thingy" I described in my original answer. It's all described in the linked document.
    – Paul
    Commented Mar 8, 2013 at 5:11

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