While looking through my email I came across some very useful homeowner tips from Dan LaBrake at Housemasters. Here’s a good item regarding that age old problem of unpredictable water temperatures in the shower.
Ever step into the shower and realize that the water is not what you want? Or while you’re enjoying that nice, warm shower, suddenly a blast of icy cold water sends shivers down your spine. But what may be much worse than that is when someone flushes a toilet elsewhere in the house, momentarily diverting some of the cold water running to the showerhead, and leaves you under a potentially scalding flow of very hot water. Hopefully you’re able to safely back away; if not, there is a potential for a burn.
Scalding is the most obvious consequence when water contacting our skin is too hot; however, a second often disregarded consequence called thermal shock can also occur. This is the body’s involuntary reflex to recoil from abrupt temperature changes. You might be momentarily saved from being seriously burned if you can move out of the stream of scalding water quickly enough, but such a quick and involuntary reaction in the wet and soapy confines of a shower area may also result in a fall. Children and older or physically-challenged individuals have an increased risk from burns and/or fall injuries due to their often slower reaction times and skin that is more vulnerable to scald burns from hot water.
The cause of this temperature fluctuation is a basic issue of supply and demand. When a toilet is flushed, cold water immediately begins to flow into the tank to refill it, causing the water pressure in the cold-water pipes to dip. If this happens when someone is showering, the amount of cold water available for the showerhead temporarily drops, changing the previously set mixture of hot and cold water to mostly hot only.
A similar condition happens when a hot-water faucet is opened elsewhere in the house, but in this case the hot water volume to the showerhead can drop, causing the water to momentarily turn cold. This problem is more evident in plumbing systems that are undersized or old and clogged with mineral deposits. An energy-saving showerhead designed to reduce water flow can exacerbate the problem.
One way to eliminate these potentially hazardous temperature shifts is to install a pressure balanced anti-scald valve or thermostatic temperature control valve in the shower wall where the shower controls are located. A pressure-balanced shower valve is designed to compensate for changes in water pressure.
Though it may look like any other shower or tub valve from the outside, it has a special diaphragm or piston mechanism inside that moves with a change in water pressure to immediately balance the pressure of the hot and cold-water flow. These valves are designed to keep water temperature constant, within plus or minus 2° to 3° F, but do so by reducing water flow through either the hot or cold supply. Most reduce the water flow to a trickle if the cold water supply fails. A thermostatic valve may temporarily shut-off the flow altogether.
Most existing bathtubs/showers can be retrofit with a new anti-scald valve; however the cost and labor involved will depend on the type valve currently present, accessibility to the plumbing, and the type of tile or other surface finishes present. If a proposed price appears high, consider that there may be other types or brands of anti-scald valves that offer a more reasonable alternative for your particular situation. Less expensive devices are also available to add at the showerhead or bathtub spigot.
Note: These tips are only general guidelines. Since each situation is different, contact a professional if you have questions about a specific issue.