I recently moved to an apartment where temperature of water in the shower fluctuates and we called for a plumber. He either cleaned up or replaced one part (I think it was the mixer - nothing visually changed), saying that it might because of stone buildup in the plumbing.

Unfortunately, the temperature still fluctuates (but maybe a bit less). Basically the problem is that in the middle of showering, the temperature can drop to one that is way too high or too cold (and then after maybe a minute drop back). This can happen about twice within 10 minutes.

I wonder if installing a cheap thermostatic tap would help here? My reasoning is that at the very least, it should help me avoid the temperature going too hot, am I right?

  • When did anything cheap pay off? Since there are problems you need a good one that you can set the temp and let the valve control the temp, these are usually more expensive. – Ed Beal Feb 5 at 15:32

Get the Plumber back. He may have just cleaned, flushed &/or adjusted the Mixer & not replaced it. But, it sounds like you have a Pressure-Balancing valve instead of a Thermostatic valve. So yes, see if the Plumber can replace the current valve with a Thermostatic valve, this would be the long-term permanent solution.

Just an FYI. Not in all but in some apartment buildings, there can be constant water uses to justify your current fluctuations in that short amount of time. Like, refrigerator ice makers, leaking toilets, building humidifiers, specific laundry machine final rises or someone filling a cup. It may be unavoidable or just unlucky timing with your current valve.


Would it help to install a small pressure tank on the hot and cold lines? You'd have some stored pressure in each case when the line pressure drops because somebody flushed the toilet.

Something like this, https://www.homedepot.com/p/Eastman-2-Gal-Thermal-Expansion-Tank-60022/205364872

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