I have a Noritz tankless hot water system and Delta fixtures in the shower. The shower water gets too hot and when I try to regulate it the hot water goes off. I have to turn the hot water on full blast to get the water hot but I am still not able to regulate the water to a comfortable temp. I reduced the temp on the Noritz from 120 to 105 but am still having the same problem. Please advise.

what is happening to other faucets in the house?

The problem just seems to be in the shower. Other faucets in the house have separate hot and cold controls and there is no problem.

Are you using a low flow shower head that restricts water to under 2.0 gallons per minute? I would swap heads with one that uses 2.5 gallons per minute and see if the problem stops.

or, have the water running in the sink and turn on the shower for a bit to see what happens.

Tankless water heaters can be a pain in the __s. Maybe the newer versions have capabilities that the older ones don't have. If not I would shy away from them.

Thanks. I will give your ideas a try. Is their an anti scold or a mixing valve that could cause this problem?



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Some valves need to be taken apart and soaked in 50% vinegar and water to clean the minerals so they function properly. Find out if your water is alkaline or has excess minerals in it.