Best RV Thermostatic Shower Mixing Valves 2024 - Installation Guide

The Quick Answer

For RV thermostatic mixing valves, I highly recommend mechanical models from established manufacturers - verify the correct part for your model (verify with dealer). Both compact designs are reliable and designed for tight spaces. As for digital models, premium systems from major manufacturers can work in RVs, but they require 120V AC power and significant plumbing modifications. Avoid cheap units from unknown manufacturers - they fail quickly and replacement parts are impossible to find. Stick with established brands like Symmons, Powers, or Watts for reliability on the road.

What's Causing This

You're absolutely right to want a thermostatic mixing valve in your RV. Standard RV shower valves are notorious for temperature fluctuations, especially when the water heater cycles or when someone uses water elsewhere in the coach. This happens because RV plumbing systems have smaller diameter pipes and limited hot water capacity compared to residential systems.

The challenge with digital thermostatic valves in RVs isn't just installation space - it's power requirements and durability. Most digital units are designed for residential 120V constant power and don't handle the vibration and power fluctuations that RVs experience. The good news is that modern mechanical thermostatic valves work exceptionally well and are much more reliable for RV use.

Temperature inconsistency also stems from the fact that many RVs have inadequate mixing valve placement. Installing a quality thermostatic valve near the shower will solve temperature swings, prevent scalding, and actually extend your hot water supply by maintaining consistent mixing ratios.

Tools You'll Need

• Pipe wrenches (10-inch and 12-inch)
• Tubing cutter or hacksaw
• PEX crimping tool and rings (if using PEX connections)
• Teflon tape or pipe thread compound
• Adjustable wrench set
• Drill with hole saw attachment (may need to enlarge access holes)
• Multimeter for testing any electrical connections
• Level for proper valve orientation

Step-by-Step Fix

SAFETY WARNING: Turn off electrical power to water heater and allow system to cool completely before beginning work. Wear safety glasses when cutting pipes. Check local codes and RV manufacturer warranty requirements before modifying plumbing systems.

Planning and Preparation: First, turn off your water pump and drain the system. Locate your hot and cold water lines near the shower - you'll need at least 8 inches of straight run on each line for most thermostatic valves. Check space requirements for your specific valve model.

1. Cut into the hot and cold water lines approximately 12 inches before they reach the existing shower valve
2. Install the thermostatic mixing valve according to manufacturer specs - inlet temperature should be set according to manufacturer specifications and maximum temperature stop should be set to prevent scalding
3. Connect the mixed water output to feed your existing shower valve's hot water input
4. Connect the cold water line directly to the shower valve's cold input
5. Test all connections for leaks before closing up walls
6. Calibrate the thermostatic valve by adjusting the temperature control according to manufacturer specifications while monitoring output temperature with a thermometer

For Digital Options: If you're determined to go digital, premium systems can work but require running 120V AC power from your RV's electrical panel or installing appropriate DC to AC inverters (verify voltage requirements with manufacturer). You'll also need manufacturer's app for setup. Installation time jumps from 2-3 hours for mechanical to 6-8 hours for digital due to the electrical work required.

When to Call a Pro

Call a professional if you discover your RV has unusual plumbing configurations, such as a recirculating hot water system or if the hot and cold lines are buried deep within structural elements where access requires major disassembly. Some higher-end RVs have complex plumbing manifolds that require special tools and knowledge to modify safely.

Also consider professional installation if you're not comfortable with the electrical work required for digital systems. SAFETY WARNING: Improper 12V electrical connections in RVs can create fire hazards, and the wiring must be done to RVIA standards. A qualified RV technician can also help you determine if your water heater and pump system can handle the flow requirements of your chosen thermostatic valve, and verify that your water pressure is compatible with both the valve and RV plumbing system - some smaller RV systems may need upgrades to work properly with high-flow mixing valves.