By Greg Illes
Many modern homes enjoy the benefits of a temperature-controlled shower. No more hot and cold valves, but rather one handle for setting water temperature, and one handle for controlling the flow. Once hot water reaches the valve, the output temperature never varies, and you never have to “fiddle” with the hot and cold knobs (in fact, there aren’t any) while you’re being frozen or scalded by a bad adjustment.
Different users of the shower simply remember their personal temperature setting, and set the handle to that position before turning the flow on. Variations in hot or cold input water temperature are no longer a problem — the temperature controller compensates, and you still get your requested water temperature.
Unfortunately, most such valves take up a LOT of space behind the wall, and are difficult to retrofit to an RV. Also, most valves incorporate a separate shower feed, which then requires a separate hole and fittings in the shower wall.
Enter the Grohe Grohtherm 3000 series of thermostatic control valves. These are available from plumbing supply houses and even from Amazon. It’s a well-made European product that works well for retrofit applications. This model has all of its control valving on the shower side of the wall — virtually no space is required behind the wall — and it will fit almost any existing RV. Furthermore, the Grohe also has a built-in shower hose connection, making it even more compatible.
In addition to providing guaranteed comfort, the temperature-controlled shower will also save water. You will not have to spend “water time” adjusting the temperature, nor will you have to wait that extra half-gallon to make sure the hot water is there. Since the valve has built-in backflow-prevention valves, there is no necessity for that water-wasting trickle when you shut off the water to soap up — you just turn the flow handle off. It even has a “soft-start” feature which prevents surges and temperature fluctuations.
Installation can be a three- to four-hour DIY project that costs around $300. The valve is somewhat heavy, and you’ll want to add a reinforcing piece of plywood to the outside of your shower stall. A new backing plate can be made from a piece of half-inch white polyurethane.