Just finished building my somewhat modest master bath addtion (I did all the plumbing myself). My experience deals with a stand up shower in this particular instance. After some resarch, I decided that I did not need to spend north of $2k on Kohler thermo valve, and I did not need 15+ GPM with 3/4" inlets. By the time I added the body sprays and a couple of shower heads i was in for over $3k which was way over budget. I ended up doing a Moen Vertical Spa. IIRC, I think it was about $1,300 with two shower heads, 4 body sprays, a handheld shower, 5 position diverter valve, and the thermo mixing valve. I just fired it up last week and am very happy with the whole set up. Moen does a nice job, they have some great info on their vertical spa and thermo valves on the moen.com website. It took me a full day to pipe, but I used long radius elbows and took my time to ensure good flow. Having both the pressure balanced and a thermo valve, I prefer the thermo valve and being able to adjust the flow volume. Plus I think it looks better. I ordered it online from faucet.com, no tax + free shipping....plus they price match. If you google the part number and you find a lower price and email it to the price match department and they re-quote the product. Customer service was superb and ended up ordering my sinks, faucets, med. cabinets, and towel/TP holders from them. Again, with no tax and free shipping the net result (to me) was a great deal. I go out of my way to keep from purchasing at the big box - but that might be my personal grudge, but they dont have anything "good" in shower valves in stock any ways, so why bother ordering it from them? Hope that helps.

In my experience with the Bosch Aquastar, the more hot water demanded at a single point of use, the better the unit performs. It can produce about 5 gallons per minute of hot water with a 50 degree temp rise. Pressure balance and thermostatic controls have check valves inside. I think they restrict the water flow a bit in order to find an equilibrium. Tankless water heaters reduce the hot water flow in order to achieve the proper temperature. This feels like less pressure in the shower. Some people install a small pump in line directly after the tankless heater. It is activated by a flow switch to turn on every time the hot water flows. This supposedly helps equalize the hot/cold water pressure.

What the heck!? Being a "you get what you pay for" type, now I'm not feeling so good about my choice :o My 57 year old husband has been asking, "can't you just find a tub faucet like the one I have now...a spout and two handles? How hard can it be?" The Delta In2ition Linden shower and tub spout (with one handle mixer) is just under $200. I finally found the tub spout and TWO handles that match his Addison sink faucet. Does NOT include a shower setup....$625!!! Whaaaaat? What possible reason could there be for the spout and TWO handles costing that much more than a 2in1 shower/tub spout/one handle combination? Better/higher quality parts has to be the reason. So I called him with the good news <g> Turns out he can live just fine with the 2in1 shower/tub spout/one handle combination. OTOH, I'll be forever waiting for the thing to fall out of the wall and flood the house (insert slapping forehead here).

Yes, if the pressure balanced valve senses a drop in the cold water supply pressure, an internal valve moves to cut down the pressure of the hot water as well. Thus, the flow from both hot and cold are momentarily reduced together and the outgoing temp remains fairly constant. If the hot water pressure would suddenly drop, the opposite would occur. This balanced valve operation is quick, in a fraction of a second, and fairly inexpensive to implement. The thermostatic valve adjusts the outgoing water temperature via a slower changing sensing mechanism. Any change in water temperature has to soak into/out of the wax element in your drawing (it is likely inside a brass housing as well), so it takes many seconds for the heat to soak into/out of this element and effect a change in the balance of hot and cold water. This is much too slow a process to protect one from scalding from the flushing of a nearby toilet; with only a thermostatic valve present, the drop in cold water pressure & flow could cause a scalding event to occur. This thermostatic design is also a fair bit more expensive to produce which is why far fewer homeowners have them installed.