Can I Use PEX For Hot Water Or To Water Heater? Pro Tips

Are you conflicted about using PEX for hot water or the pipeline to the water heater? If yes, then rest assured because we have the answer to all your queries.

Everyone knows PEX has many advantages when you want your work done fast and efficiently.

However, when it comes to using it for a water heater, you have to take particular measurements to prevent future accidents.

With proper knowledge, perfect pipe selection, and expert installation, you can use PEX for hot water as well as the water heater. 

Are you curious to know how you can do it? Without wasting any time, let’s get into it!

Can I Use PEX For Hot water?

When the question arises if you can use PEX for circulating hot water or not, then there are many points you have to understand. 

You must have seen rolls of pipes at the construction site or during any remodeling project. Generally, PEX pipes have different varieties when it comes to a specific installation. Its particular color codes distinguish its use, whether it is for hot or cold water or both.

PEX Color Break Down:

  • Red: Hot water
  • Blue: Cold water
  • Grey or White: Hot & Cold Water

So, when you want to use PEX tubing for hot water, plumbers will install red PEX pipes that are capable to withstand heat. It is recommended that the water temperature not be more than 100-120 degrees Fahrenheit as it can lead to bad consequences.

PEX had a bad reputation until recently, there wasn’t enough flexibility to use PEX pipes for hot water. However, the revolutionary invention has now made our heating system inexpensive than before. Thanks to its low price point.

Advantages of Using PEX Pipes To Circulate Hot Water

Advantages of using PEX in the piping system that will carry hot water are as follows:

1. When PEX is used in heating systems, and hot water runs through it, it helps to radiate the whole room. It is popular for radiant floor heating.  

2. The oxygen barrier present in the pipe protects the ferrous components of the heating system from corrosion.

3. PEX is preferable for hot water because it has flexibility as you can easily bend the pipe to the corners of your house.

4. There is no need to use connectors or open sheetrock to install pipe for hot water running.

5. Their flexibility can expand when the water temperature is high and contract when the temperature drops from a specific level.

6. Moreover, when you choose PEX to water heater or for hot water, then you have the advantage that they are easy to replace if any problem arises.

7. The Manifold system of PEX prevents energy losses so that hot water arrives at speed from the tap.

hot water system with pex under floor

Disadvantages of Using it For Hot Water

It seems that there are some safety issues and disadvantages when you use PEX pipes and fittings for hot water. So, let’s get to know what they are:

1. PEX piping can’t sustain high temperatures, so the standard temperature ranges from 120- 150F when connected to hot water.

2. When the temperature rises, the connected pipe will melt or get cracked. Furthermore, the hot water gets leaked easily from the pipes when they can’t accommodate ultra-high temperature.

3. In some circumstances, the installed PEX pipes become susceptible to moisture, and as a result, the water becomes contaminated.

4. When PEX pipes are exposed to UV rays, there is a high chance that chlorine exposure in water can lead to cancer. In the worst cases, you can get legionnaires disease in which your skin has scald on it.     

Can I Use PEX To Water Heater?

You can use PEX pipes to the water heater, but you need to connect the heater with a metal pipe first, and then connect the PEX pipe with that metal tube. There should be a minimum of 18-inch metal pipe before the PEX pipe.

You can use red, white, or grey PEX pipe for connection as red carries the hot water, so the white tube can be used for hot or cold water. Most people prefer white over grey though both have the same use. If you are DIY, then white PEX pipes are preferable to connect with a water heater than the red one.

However, you should be vigilant when picking up the PEX pipe for the heating system or connecting with the water heater. Wrong pipe can lead to a life-threatening injury.

Each PEX pipe is rated by code, and it can withstand up to 210F temperature for two days.

If the temperature exceeds that point, then the pipe will start melting, and people might get serious injuries because of the extremely hot water leakage. To avoid this problem, you should only use PEX after using a small 18 to 24-inch metal tube as a buffer zone. Plus, make sure not to overheat the water beyond the acceptable limit of the PEX.


Lastly, you now have adequate information about whether you can use PEX for a hot water/water heater or not. Everything has its own advantages and disadvantages when it comes to its usage for a particular thing.

PEX pipes can be used for hot water as it improves the radiant floor heating system. The water runs fast as it consumes less energy and prevents the ferrous components from rusting.

Although, they are also vulnerable to moisture which contaminates the water as it increases bacterial growth. When it comes to the water heater, then the PEX pipes should not be used within 18 inches from the heater.

I hope this article fulfilled its purpose of providing you the information you have been looking for!

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