The installation is easy if you are amenable to a pressure balanced valve instead of a thermostatic valve. If you feel the need to read a little about the differences between PB and TS valves, read here.

If you want thermostatic valves then it does get a bit more complicated, as you'll need quite a few separate components.

So just to save myself some time, you're definitely set on thermostatic?

Thanks for the help, mongoct. We're definitely committed to thermostatic controls, having been spoiled by them on several recent hotel visits. This will be the only shower in the entire house so we want it to be exactly right. It has to handle daily showers for two adults and bathing/splashing time for a young child.

listener, we just put in the Hansgrohe thermobalance III valve. It does exactly what you're looking for, all in one valve. It is fabulous, because you can do either the tub filler, the shower-head, the hand-held, or you can do the shower head and hand-held at the same time. Of course you'll need to buy all the accessories such as the showerhead, hand-held, slide bar, etc, but it does what you want without any additional valves. Plus it's thermostatic too.

Okay, thermostatic it is.

Will you just be operating one fixture at a time? Just the tub spout, or just the showerhead, or just the handheld?

Or would you prefer just the tub spout by itself, plus the option of running the handheld by itself, the showerhead by itself, or the showerhead and handheld simultaneously?

mongoct,

what is the difference between being able to use multiple faucets at the same time and only using one at a time? Is it a matter of getting one diverter v. another, or of getting 3/4" pipes v. thinner ones? Is it considerably more expensive to be able to run the shower and handshower at the same time? I don't think it's that important to us, just as long as we can control the flow without futzing with the temperature.

Brendog's thermobalance III seems to allow multiple faucets at the same time, but I've heard that it doesn't really allow flow control, just on/off separate from temperature. Is this correct?

I also assume that any valve/trim combo that is thermostatic has the ability to keep temperature constant when toilets are flushed and to prevent babies from burning themselves. Is this assumption correct?

listener, your review of the thermobalance III is correct. its really not ideal at all. you're best installing a thermo valve (Grohe 3/4" will give you high volume when needed), with 3 separate volume controls. you're good with a 1/2" valve for the tub, you may want 3/4" valves for the shower head and hand shower.

The valve ONLY allows you the combo of hand-held/shower head to operate at the same time. But frankly, this is the only option that really makes sense to be in operation at the same time. It's not really a necessity, but it's more of a luxury to be able to turn on the hand held while the shower head is on. You may see a slight drop in pressure when both are in operation, but it's not a big deal.
And yes, of course there is an anti-scald valve, that's pretty standard with all shower valves.

Thermostatic setups usually have separate volume and temperature controls. You set the temp with one knob and you can leave it there for a little while or leave it there forever. You control the flow, from off, to a trickle flow, to medium flow, to full flow, with a separate volume or flow control knob. Once the temperature is set on a thermostatic valve the temp will generally stay within +/- 1 degree regardless of other plumbing being used in the house.

Pressure balanced valves usually have the temperature and volume combined in the same handle, the rotation of the knob changes the desired temperature, and as the knob is rotated your water flow essentially goes from full off to full on. There's no real intermediate flow setting. Pressure balanced valves generally hold the temperature to +/- 3 degrees.

Within the Stillness line, there are variations within the individual items themselves; 1/2" valves versus 3/4" valves, valves with stops, etc. I'm not vetting out 1/2" versus 3/4", you'll have to do that on your own. But here are the essential parts that you'll need:

1) The main valve body, it can be the K-680 since you mentioned having both controls on one valve. An option would be the higher volume K-670 valve.

1a) You'll need a trim kit for the 680 valve.

2) Out the bottom of the K-680 you'll have a short length of copper leading to the tub volume controller, a K-681 valve. An option would be the 3/4" K-671 valve.

2a) You'll need a trim kit for the 680 volume controller.

3) Out the bottom of that valve you'll have another stub of copper leading to your tub spout.

Now that the tub is taken care of, let's get on with the shower heads.

You'll have a stub of copper coming out the top of the K-680 valve listed above in paragraph 1).

4) That will lead to your K-687 diverter or tranfer valve.

4a) You'll need a trim kit for the K-687 diverter valve.

The valve can be plumbed to divert to either two or three outlets, in your case you'll only use two; one for the shower head, one for the handheld. The diverter valve has an inlet in the bottom and three outlet ports, one at 9 o'clock, one at 12, and the third at 3 o'clock.

5) Plumb the ones at 9 and 12 o'clock together and send their output to the shower head.

6) The outlet at 3 o'clock will run to a wall outlet for the handheld.

7) A hose will be connected to the wall outlet.

8) A handheld will be connected to the hose.

9) The handheld will hang on the slide bar which will be attached to the wall with the slide bar trim kit. I'm not sure if the slide bar trim kit is mandatory or just a pretty item.

That's my best guess at what you need for the setup you described: Kohler Stillness thermostatic valve with built-in volume control, outputting to just a tub spout, or outputting to either a shower head or a handheld, or to the shower head and heldheld simultaneously.

Mongo

One last thing. If you DON'T want to run the handheld and shower head at the same time, you can still plumb it as I have listed. The diverter valve can send water to the shower head alone, the hand held alone or both at the same time.

An alternative would be to take the output coming out the top of the main 680 valve and branch it off to two separate 681 volume valves, one 681 valve feeding the shower head and another 681 valve feeding the hand held. Obviously you could turn on just the 681 for the shower head or the 681 for the hand held, or turn them both on for simultaneous flow.

You just have to balance the cost and aesthetic of a single 687 diverter valve with trim kit and one hole in your wall versus two 681 flow valves and two 681 trim kits and two holes in your wall.

wow, thanks, Mongo. that was incredibly useful!

FaucetDIrect.com recommends a booster bump to accompany the K-680 valve. I've never heard of this thing before, and I'm suspicious that it's just an upsell item.

I'm a little confused about this setup. Hopefully you can help clear things up for me.

The two-handled thermostatic trim: one sets the temperature, but what does the other handle do? Mongo listed a tub volume control that is separate, but no separate shower head/hand shower volume control, only a diverter. How do I control the volume of the showers? Is that what the second handle on the thermostatic trim does? If so, it seems like the water is directed through that before being sent to the tub control, which seems redundant.

If I were designing a shower/tub combination, without concern for the sorts of fixtures that were available, it would have the following:
*One control lever for temperature.
*One control lever for volume.
*One diverter lever, with settings A (tub), B (showerhead), C (handshower), and BC (showerhead and handshower simultaneously).

That's three knobs and three locations from which water can reach a person's body. Is this possible, with or without the Stillness series?

Conversely, I could eliminate the overhead shower and use the handshower as an overhead, to make things easier and more affordable. Is this a good idea?

The Hansgrohe Thermobalance III mentioned above does all three functions with only two controls. One control is for temperature. The other control is volume and diverter in one. Turn it a little bit to the left, you get a little flow out of the tub; turn it a lot and you get stronger flow. Turn it to the right of center, you get flow out of the showerhead, keep turning it past full flow, and it will start mixing both the showerhead and handshower; turn it all the way right and it turns off the showerhead and just supplies the handshower. So you have A, B, BC, or C. And this is all accomplished with one valve in the wall, and one trim piece on the wall.

-- Eric

That's exactly right Eric. Another good summary of the thermobalance III. It is simple and effective.

Or you could have what looks like NASA mission control in your shower, it's up to you...

"If I were designing a shower/tub combination, without concern for the sorts of fixtures that were available, it would have the following:
*One control lever for temperature.
*One control lever for volume.
*One diverter lever, with settings A (tub), B (showerhead), C (handshower), and BC (showerhead and handshower simultaneously).

That's three knobs and three locations from which water can reach a person's body. Is this possible, with or without the Stillness series? "

For a proper setup with Stillness you'd need one more volume or flow control valve for the tub spout. Remember, this tub spout along with the TS valve doesn't have the simple pull-up tub/shower diverter knob like on other tub spouts with a PB valve.

An alternative would be to go with your initial component list above, and use the 9 o'clock port on the diverter to fill the tub, and 12 o'clock for the showerhead, and the 3 o'clock for the handheld. To plumb things that way you'd have to cap the bottom tub outlet port on the TS valve. The problem is that you'd get less volume flow through the 9 o'clock tub port on the diverter valve than you'd have coming out of the dedicated tub fill port on the bottom of the TS valve, so it'd take longer to fill your tub. I don't recommend going that route.

For the Stillness line using the 680 two-handled valve, the minimum you need to properly plumb the setup is a 680 valve that contains temp control and volume control, a 687 diverter to direct flow to the showerhead and/or the hand held, and a 681 volume valve to control flow to the tub.

An alternative in the Stillness line would be to step away from the 680 valve that you mentioned that you want to use and go with the K-679 valve. The 679 valve is just a temp control with no built-in volume control.

To plumb your setup with a 679 valve, you'd need:
- a 679 valve to control temp.
- a 681 flow valve connected to the 679's bottom outlet port for the tub flow control.
- The 679's top outlet port would "T" off to two 681 flow controls, one for the shower head and one for the hand held.

So by going with the 679 instead of the 680 you'd need one 679 TS valve and three 681 flow valves.

That's getting away from the 680 valve that you originally wanted, but staying within the Stillness line and staying with a thermostatic setup.

If you can get away from the Stillness line, at least just for the control valve, then look at the Thermobalance III valve. I've probably installed more TBIIIs than any other TS valve.

You can still use the Stillness showerhead, handheld, and tub spouts, and there is a trim kit for the TBIII that sort of resembles the Stillness trim kit. The TBIII combines temperature selection, flow control, and diverter all in a single valve. It's well designed and time tested.

"The TBIII combines temperature selection, flow control, and diverter all in a single valve. It's well designed and time tested."

Gee, that's pretty much exactly what Eric and I said already...

"Gee, that's pretty much exactly what Eric and I said already.."

Yes, you are correct. You did already mention it.