Our shower doesn't get hot enough even with the knob turned all the way, I measure about 90 degrees F. A sink faucet in the same room at the same time shows 115 degrees F. The hot water pipe leading into the mixer assembly is too hot to touch, so it seems that enough hot water is getting all the way to the shower.

From reading other questions here it seems that these shower mixer assemblies usually have some kind of limit/adjustment mechanism, however I can't find it in this one, and it appears that the manufacturer went out of business a few years ago so I'm unable to find anything online about this particular brand (“Coventry Brass Works Limited”).

Does this particular assembly look familiar to anyone and is there a way to adjust it?

Here are some photos:

Temperature measured at shower

Temperature measured at shower

Temperature measured at faucet

Temperature measured at faucet

Shower assembly

Shower assembly

Shower assembly close up with handle removed

Shower assembly with handle removed

Shower assembly handle

Shower assembly handle

  • 1
    It looks to me like the handle can spin freely but the turning valve inside (with the gears) is what has its range restricted. Is that right? Commented Dec 29, 2014 at 20:22
  • The handle actually has limited movement, I think that's because of the interplay between the part of the handle that's machined away along the rim and the metal part that's barely visible at the top of the assembly close up photo. I tried to pull the handle straight out and adjust it clockwise so the stop would kick in later, but that didn't change anything. When I turn the valve with the gears directly with my hand, it also hits a stop. I will try your suggestion with the white plastic piece. Commented Dec 29, 2014 at 23:36
  • Copy your update and paste it in as a new answer (self-answering is fine, even encouraged) and then accept it so the question shows up as having an accepted answer.
    – Ecnerwal
    Commented Dec 13, 2021 at 23:40
  • @Ecnerwal good idea, done. Commented Dec 14, 2021 at 5:20

2 Answers 2


Update December 2021: Stackexchange notified me that this question I posted in 2014 is viewed a lot, so I thought I'd update it.

We had a plumber come out in 2015 and they couldn't fix it. In 2018 we had another plumber come out and they correctly identified the part that was causing the issue (which apparently is called a thermostatic cartridge). The old cartridge was very old and completely filled up with calcium deposits that blocked the passage of hot water. I ordered and installed a replacement part, and that fixed the problem completely.

The part is called “Rohl 9.13554 Perrin and Rowe Thermostatic Cartridge”. I ordered it from a distributor called supply.com.

As an aside, the shower hardware is from a brand named “Coventry Brass Works”, which apparently was distributed by Home Depot and went out of business in 2008. That makes it hard to find parts and information.

So the good thing is that the cartridges don't seem to be manufacturer-specific. Even if the hardware is no longer available, you might still be able to find the cartridges, as in our case.

  • 2
    Thanks for taking the time to update your own, old question. You never know when someone might find an old post helpful
    – bsd
    Commented Dec 14, 2021 at 11:21
  • 2
    Indeed, follow up on 12 year old question is fantastic! I'd be tempted to buy a 2nd cartridge, just in case they stop making ones to fit your faucet...
    – FreeMan
    Commented Dec 14, 2021 at 17:20

If I am interpreting the pictures correctly, I think the white plastic piece that sits inside is the limiter. Carefully remove the U-shaped locking piece, taking care not to damage the piece slide the white piece out some and turn it counter clockwise slightly and re-set it.

Lock it back in place, and test the water max temperature again.

  • Unfortunately it appears that the white piece doesn't slide out after removing the U-ring. What's interesting is that after removing the ring, the valve can be pushed in a little bit but that didn't lead to anything. I played around and at one point turned it all the way clockwise (to the cold position) and noticed that at that point it can no longer be pushed in. I'll try fiddling with this some more once I use the shower the next time. The way it's set up it's hard to try it out without getting wet... Commented Dec 29, 2014 at 23:49

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