How to Fix a Shower Anti Scald Valve

What You'll Need
Instruction Manual
Spray bottle

Anti scald valves are key to a safe home, especially homes with young children or elderly people. These devices eliminate the hot or cold water shock that occurs when there is a fluctuation in the water lines. The fluctuations can occur with a flushing toilet or by turning on a faucet. Because the valves are expensive, it is important to try to fix yours before you throw it out.

Step 1 - Read Instructions

It is extremely important to read through the instruction manual first before doing any work on the anti scald device. This is because there are many sensitive parts within it that should be handled with care.

Step 2: Mismatched and Upside Down

A good place to check if your anti scald device is malfunctioning is the water lines. Often at installation, the hot and cold lines are accidentally switched when connected to the faucet. Fixing this is simply a matter of switching the lines into their correct position.The top and bottom of the faucet is not always clearly marked. This means that your anti scald device could have been installed upside down when attached to the faucet. Consult the instruction manual for indications of which side is up and which is down.

Step 3 - Unclog Lines

After soldering, if the water supply lines were not thoroughly flushed, they could be clogged with solder, flux, pipe dope, rust or sand. If you see these lines clogged, you will have to clean them out. Use a household cleaner or simply flush with water and soap. Using a thin brush with stiff bristles is also helpful at scraping away foreign particles. 

Unfortunately, anti scald mechanisms are sensitive to becoming clogged. This can happen if you have placed too much pressure on the mechanism too quickly. This is done by opening the hot water and letting it run. Water supply valves should be turned on slowly. Keeping a balance is the primary function of the anti scald valve.

Step 3 - Replacement

If you find the anti scald mechanism is beyond repair, then you will have to look into replacing it. There are three types of anti scald valves to choose from. There are anti scald pressure- balanced devices that function by taking note of the changes in pressure in the water. Thermostatic temperature control valves actually have a thermostat built into it and regulate the temperature of the water. These are more expensive than the pressure controlled devices. The third type is a conjunction between the pressure sensitive and temperature sensitive devices. The third is the most technologically advanced but also the most expensive. Anti scald devices can be purchased on the internet or any hardware store.