Kohler Margaux Doesn't Work w/ Tankless Navien System

[13pinkpigs]

About a year or so ago, I had the heat in my 1930s house updated from a steam boiler to hot water and at the same time I updated my hot water heater to a tankless Navien system. Since then, I finally got my basement finished and chose the Kohler Margaux cross handles which come with a thermostatic valve because this line looks similar to the era of the home.

After everything was installed by my general contractor, we realized that the valve doesn't regulate the temperature of the water for the shower correctly. It gets cold and hot, but not in the middle and sometimes stays just hot for awhile without adjusting at all.

Kohler told my contractor we need to install pressure valves because it's not set-up for a tankless system, but we don't know WHERE or AT WHAT PRESSURE they need to be set for and Kohler doesn't seem to know what pressure either! My contractor met with 2 plumbers today, but they don't seem to know either.

Any help would be greatly appreciated!

 

[OLD TIMER]

Time to call NAVIEN TECHNICAL SUPPORT.

 

[Sponsor]

 

[13pinkpigs]

Thanks! We have done that. I'm looking for anyone who has come across this same problem and tried installing pressure valves...

 

[OLD TIMER]

I would call Kohler back and see if they'd be willing to send you a new cartridge for your shower to see if that's the problem.
Then you'll both know.

 

[Tuttles Revenge]

I think what is going on is that the Kohler valve only regulates the temperature of the water, not the volume. You need a Volume or Transfer valve to regulate the on/off of the shower.

What they are referring to by "pressure valve" is probably a pressure balance valve which regulates both the temperature of the water but also the volume of water. An example of the Kohler Margaux K-TS16235-3- with pressure balance.

Based on the provided info above, you likely installed the Kohler Margaux K-T16239-3. It will likely be K-2972-KS-NA Mastershower® 1/2" thermostatic valve. You will not be able to change the cartridge out to fix this. Most likely you would need to open up the wall and install a volume control valve.

Whoever provided the fixtures or installed them should be calling Kohler to verify.

If the installation of the shower system checks out ok.. then I'd look at how much volume of water the shower is using. A typical 199k btu tankless only delivers 5.5 GPM of 120° water. So if you are consuming more than that, you will get cold water from the heater.