Kohler 3/4" Thermostatic Mixer Valve K2976 (stacked)

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Leah F.

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Hello,

I am trying to understand the specs on a stacked Kohler valve and I am getting conflicting answers from customer service. I am trying to understand what "dual outlet" means and what it means when it says "bottom outlet requires separate control". Will I still have to get a volume control for the tub or will the stacked volume control work for both the tub and the shower? Does anyone work with this valve?

I was going to have this installed on tub/shower combo with only a shower head and a tub diverter spout plus twin ell.

Here's the valve link: http://www.us.kohler.com/us/Masters.../productDetail/Thermostatic-Valves/428603.htm

Here's the spec sheet link: http://www.us.kohler.com/webassets/kpna/catalog/pdf/en/1145569_4.pdf



Thank you!

LF
 

Jadnashua

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First, unless you have a very large soaking tub, you might want to save some money and get the 1/2" version of this. The 3/4" version will flow more, and fill the tub faster, but if you only have one shower head, it is probably overkill, and more expensive.

You have two ways to plumb this which is covered in the rough-in document http://www.us.kohler.com/webassets/kpna/catalog/pdf/en/1145569_4.pdf .

If you want to use a diverter spout, you'd plug the bottom outlet, and run the top outlet to the twin-el and then to the tub and shower head.

If you want to be able to run both the tub and the shower head simultaneously, you'd need a separate volume control and route the bottom outlet to it, then to the tub spout (no diverter spout). Using the bottom outlet to fill the tub will enable higher volume and therefore fill the tub faster by about 25%. It talks about needing an aereator in some situations...I'm not really familiar with that, but it is required if you do not want both the shower and the tub to fill at the same time...the flow can back up in the spout and force water up to the shower head without it. On most valves, the twin el does that, but apparently , not on this one.
 

Leah F.

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Jim,

Thank you, now it is starting to make sense. From what you are saying about the 3/4 inch valve, does that mean that if I were to plug the bottom outlet (i.e. not to run the tub spout and the shower head simultaneously), then my flow rate would be limited by the capacity of the top outlet? Do you think the flow rate of the top outlet is at least 7 gpm?

Yes, I am considering the 1/2 inch valve (K2973) mentioned. Did you notice anything special about it for my situation (shower head and tub spout w/diverter and twin-el, only, in my tub-shower combo)? It will still get 7.2 gpm, out the tub spout, right?

LF
 

Jadnashua

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From the product description page for the 3/4" valve: 17.2 gpm (gallons per minute) flow rate through bottom port and 14.9 gpm flow rate through top port for that valve. A typical showerhead is limited by federal standards to 2.5gpm, so you'd still have nearly 6x more water than the shower head could use with just using the top outlet. IMHO, a 3/4" valve only makes sense if you have a huge tub to fill or plan many shower outlets. The 1/2" valve claims 7.2gpm from the top port, which again, is fine for a single (or maybe one head and a couple of body sprays). Now, they didn't say at what pressure that volume is available (typically around 60psi) and if your pressure is less, you may see less.
 

Leah F.

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Again, thank you for interpreting it all for me. I agree that the 3/4 inch will be overkill for the tub I am choosing (60 gallon Kohler Bancroft) but I really needed to understand what the 3/4 " was offering--just in case!

Have you found that 7 gpm is a sufficient speed to fill a 60 gallon tub--i.e. the water won't be cold by the time it is filled?

LF
 

Jadnashua

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Some people are impatient, so a faster fill rate is worth it to them. Note, that you need at least 3/4" lines all the way back to the supply line and water heater...IOW, you can't just upsize them along the way. If it takes longer than you really want and things cool off, you can always start with it going in warmer to compensate.
 
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