How to Fix Fluctuating Shower Temperatures

Close-up of a shower knob
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Nothing ruins a relaxing shower like a sudden shot of ice-cold—or scalding-hot—water. Fortunately, pinpointing the source of your erratic shower shifts isn’t difficult. Here’s a quick look at what’s causing your changing shower temperatures, and how you can address it.

Pressure-Balancing Valves

If your shower temperatures change when someone flushes a toilet or turns on a sink, your pressure-balancing valve may be at fault.

Pressure valves open and close pipes in accordance with water flow. If cold or hot water levels drop, in the event of a toilet flush or a dishwasher cycling on, a faulty pressure valve could make up for the drop in pressure by sending scalding or freezing water through your shower. Replacing your pressure-balance valve isn’t an easy job and will require the help of a professional.

Water Heaters

Unexpectedly running out of hot water is a common sign of an underpowered water heater. Water heaters come in a variety of sizes, each designed to heat a specific amount of water. Multiple showers, high-volume shower heads or custom sprayer designs can deplete smaller water heaters sooner than expected. As a rule, most showers use between two gallons per minute. Looking at the volume of your water heater (which is usually located on a sticker on the side of the tank) should give you a rough estimate of the amount of time you’ll have before running out of hot water.

If your water heater isn’t large enough to heat all of your showers, it’s best to call a pro to perform a replacement. Many water heaters utilize gas and electric systems in order to function. Working around these devices without the appropriate knowledge can result in personal injury and damage to your home.

Tankless Water Heaters

Tankless water heaters are a popular option for many homeowners seeking an energy-efficient alternative to traditional heaters. But although tankless models will provide steady hot water, they can sometimes result in fluctuating temperatures. Tankless designs heat water on demand instead of storing already-heated water. This means that when the burner switches off, cold water can move through the line and into your shower. You can fit your tankless design with a mini mixing tank. These holding tanks house small amounts of hot water that will eliminate cold water leakage into your main plumbing lines. Updating your tankless water heater will require working with complex plumbing and electrical systems. Be sure to call a pro to tackle any repairs or updates. Attempting a DIY fix can result in serious damage to the unit and your home.