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Can You Connect PEX Directly to Electric Water Heater?

Taking a quick hot shower after a long day at work can change your mood drastically. Having an electric water heater at home will give you this heavenly feeling instantly. You can actually install the electric water heater by yourself if you are handy and have all the tools required for the job.

However the question begs, can you connect PEX to a water heater? There is no clear answer to this question as it will depend with the manufacturers’ recommendation and the state laws that guard the plumbing codes.  The International Plumbing code (IPC) that applies in most states does not give clear guidance. However, the Uniform Plumbing Code (UPC 604.13) states that “PEX pipes shall not be installed within the first 18 inches of piping connected to a water heater.”

Most water heater manufacturers give a clear guidance on their installation. Most tankless water heaters clearly state that PEX should not be connected Directly to their product. They recommend having a minimum of 18 inch of other approved piping materials at the water heater connection.

Why Keep Off Direct PEX to Electric Water Heaters Connections?

PEX has been praised world over as a revolutionary plumbing material due to its flexibility and resistance to corrosion. This notwithstanding, direct PEX to water heater connections are not recommended. If you were considering doing a direct connection, you will have to go back to the drawing board as this is not a good idea at all.

Here are the reasons why;

  • It will be a fire hazard

The manufacturers of PEX use high density polyethylene materials that are highly flammable. By connecting directly to the water heater, you increase the risk of melting and starting a fire in the house.

  • Direct PEX connection voids your heater warranty

Most heater manufacturers have clear guidelines on how you should connect PEX. If you connect PEX directly to the unit against their guidelines, it voids the warranty essentially leaving you on your own when something goes wrong with your heater.

  • It Doesn’t Meet Some Plumbing Codes

In some areas the plumbing code does not allow for direct PEX to water heater connections. The National Electric Code recommends that we have dielectric unions when joining dissimilar metals. Considering that PEX is a plastic it does not qualify as a metal to connect directly to the water heater.

  • Its More Prone to Leaking

When temperatures change, PEX is highly likely to expand and contract and this can lead to a loose connection with the water heater. This can lead to leaks especially if it is not done professionally.

  • You Risk Electric Shock

Since the PEX tubing expands and Contracts with changes in temperatures, it can cause strains on electrical connections. This can lead to electrical shorts and even fires.


Why Consider PEX OVER Copper?

When piping for your water heater, you will get different materials in the market. The most preferable material for the piping works is PEX due to its different benefits. We filed some reasons why PEX is far better than copper and you can have a look at them.

  • PEX is highly resistant to Corrosion

The cross linked polyethylene material used in the making of PEX is highly resistant to corrosions compared to all other materials including copper.

Unlike in copper connections, PEX connections will go for many years without a leak that comes from corrosion that comes over time.

  • PEX is more Flexible

Compared to copper, PEX is highly flexible. This makes it very easy to install and it removes worries of having to ensure that every pipe is straight.

PEX rarely breaks or cracks during installation which means you save a lot of money and time during installation.

  • It’s Cheaper to Use PEX

Many people prefer PEX to copper because of the cost implications. PEX is made of relatively cheap materials which make it cheap to produce and sell.

If you are buying and installing your water heater and the piping, you will get a big bonus if you opt for pex.

  • PEX is Safer

Compared to copper tubing, PEX is safer . This is because there are hardly cases of chemical leaching with PEX. PEX also has limited chances of corrosion meaning there are less leakages.

Read More: Which is Better : Pex or Copper?


How do You Connect an Electric Water Heater Indirectly to PEX?

If you have already installed PEX system in your building and you want to install an electric water heater, then you need to take note of a few things.

First know that the PEX tubing is not compatible with brass or copper fittings. This means that you will need to get special PEX fittings for your connections.

The other thing to note is that PEX is not recommended for Direct connections with hot water appliances. This means you will need to do an indirect connection.

Now here is what to do;

  1. Disconnect the electricity to the water heater
  2. Turn off the cold water supply and all other switches on the water heater.
  3. Cut your PEX Tubing to  a desired size that fits perfectly.
  4. Fit the PEX connectors on either side of the pex pipe.
  5. Pick one end of the PEX pipe and fit it to the cold water inlet on the water heater.
  6. Connect the remaining end to the cold water shut down valve.
  7. Power on the water heater
  8. Open the valve to allow cold water to flow into the water heater.


Remember to place PEX at least  6 inches apart from the exhaust pipe. The connections should also be made with 18 inches long copper or other galvanized steel pipes. This will prevent PEX expansions due to the excess heat from the water heater.


Final Word

With all the benefits of PEX tubing, you cannot miss a downside or two. One of the downsides is that it is not advisable to use it directly on electric water heaters.

It is therefore advisable to follow professional guidance when doing such connections to avoid the risk of electrical shocks and fires in the house.