Hot water shut off, water still comes out of Riobel shower fixture set to hot

[sstackho]

Hello,

Amateur here, hoping to gain a bit of knowledge. I have a Riobel thermostatic valve

I have a 3rd floor shower that isn't as hot as I'd like. We have a tank water heater in the basement with an anti-scald mixing valve.

I just did an experiment. I turned off the valve leading into the water heater and turned on all the hot faucets and showers. They all ran dry except for the 3rd floor shower, which had a half-force stream of cold water, even though the fixture knob was turned as hot as it can go.

Does this sound like a problem with this shower fixture? For what it's worth, this shower has the two knobs - one for temperature and one for on/off.

Does this sound like a problem with hot-cold water crossover? (Not sure, since all of the other taps had no water coming out.)

Either way - is replacing the shower cartridge the way to go?

As a secondary question - the 2nd floor shower wouldn't output any water at all when the hot water was shut off. Even with the knob set to cold. I can't quite figure out what's going on there.

Thanks in advance for your help!

 

[Terry]

You shower may have a temperature limiting stop. Pull the handle and move the stop.
At some locations, it doesn't allow you to swing the valve to full on hot.

 

[Sponsor]

 

[Jadnashua]

Newer valves sold in the USA (and probably Canada) are required to have anti-scald technology. WHat you have on the WH is called a tempering valve, and isn't the same thing. WHen the typical anti-scald valve loses pressure on one side, it generally progressively shuts down the other side to match the reduced flow and keep the balance of hot/cold the same. What you saw on the 2nd floor was that valve seeing the extreme - no pressure on the hot side, so it shut the cold off as well...that's how it's supposed to work.

Now the valve with the temp/volume control may or may not be working properly. Most of them have an internal stop to prevent you from using all hot (which means there will always be at least some cold). If it is a thermostatically controlled valve verses a pressure balanced one, it might still output some cold water with no hot but most of them not only use their thermostatically controlled cartridge, but also a pressure balance, and if that one does, it is either stuck, or it relies entirely on the thermostatically controlled portion to work. Without knowing the brand and model, can't say for sure.

But, most valves have an internal adjustment that limits how hot they can get. Many people never set them during install, and if it isn't a thermostatically controlled valve, even if you do adjust it in say the winter with your cold really cold, in the summer, it could get too hot, and vice versa.

 

[sstackho]

Thanks for the response, Terry.

It does have a limiter with a small button that can be pressed to turn the handle farther. I did that and it had no impact.

Upon further research, I think I am up against a complicated foe. It looks like I have a Riobel thermostatic valve that regulates the temperature. A video description is here: https://www.youtube.com/watch?v=5AjLLKoV38w

The website at http://www.riobel.ca/accueil/contenu/faq offers a solution here:

Q: The running water is not hot enough, can I adjust this?

A: Yes, the temperature can be adjusted. In order to do so, remove the water temperature handle and test the water temperature through one of the water outlets (shower head, spout, etc). Turn the cartridge counter-clockwise for more hot water, and clockwise for more cold water. Once the desired temperature has been reached, reposition the handle.

Now I just need to figure out how to get inside the darn thing!