Is PEX ok for a hot water heater?

Author: Betsy Ullrich  |  Last update: Friday, April 10, 2026

Great in All Temperatures Because of its internal composition, PEX can withstand hot and cold temperatures, from freezing to 200 degrees Fahrenheit. This far exceeds most potable water systems, which means PEX is safe to use anywhere.

Can I run PEX to my hot water heater?

Yes, PEX piping can be connected directly to a hot water heater. PEX is commonly used for both hot and cold water applications, including connecting to water heaters. However, it's essential to follow local building codes and manufacturer's recommendations for proper installation procedures and materials compatibility.

What kind of PEX do I need for a water heater?

For hot and cold water plumbing as well as for open-loop heating systems, both PEX-A and PEX-B are evident choices, yet the latter offers a more attractive combination of better health safety, higher durability and lower price.

Where should you not use PEX?

PEX pipe can be used as a service line based on its corrosion resistance to soil and water, its long life and its oxidative resistance. Our PEX pipe is not suitable for use in areas where the soil is or may become contaminated, including soil used for backfilling.

Is PEX or copper better for water heaters?

While PEX pipes are easier to install, cheaper, and more flexible, copper pipes are sturdier and tend to have a longer lifespan.

PEX vs COPPER vs CPVC plumbing pipes

Why do plumbers use PEX instead of copper?

PEX pipe is not only cheaper than copper but more durable too. PEX is immune to corrosion and mineral build-up, and it's not affected by electrolysis, which can cause small pinhole leaks in copper piping.

Can you use blue PEX for hot water?

Red and blue PEX tubing make it easy to distinguish between hot and cold supply lines. PEX is easy to service and replace, especially if you install a maintenance loop, which includes a loop of extra tubing that allows for cuts—using PEX cutters—and quick fixes. PEX is also an inexpensive option compared to copper.

Why do plumbers not like PEX?

Material Concerns: One of the primary concerns about Pex plumbing is the material itself. While Pex pipes are undoubtedly flexible, making them easier to install in tight spaces, they are not as durable as traditional materials like copper or even PVC.

Why is PEX banned in California?

Currently, PEX plumbing is one of the most widely used plumbing systems around the world. It was temporarily banned in California for a while due to concerns about toxic materials but this was later disproven by laboratory tests.

What is the downside of PEX?

Like any other material, multiple factors could lead to problems with PEX. Some of these factors could be simple over-chlorination of the water running through it or dezincification, which could weaken and break down the fittings used on the piping. Another issue could be the piping failing to pass a pressure test.

How hot is too hot for a PEX pipe?

PEX tubing can be used up to 200° Fahrenheit for heating applications. For plumbing, PEX is limited to 180° F at 100 psi. Temperature limitations are always noted on the print line of the PEX tubing.

What type of water line for water heater?

PB and PEX piping are attractive in re-circulating hot water systems because they are easy to install, they don't have the potential noise problems of copper and the plastic pipe itself acts as an insulator. Small heaters that mount under a vanity counter can provide hot water immediately.

Can PEX be used for water heater pressure relief valve?

Acceptable relief valve discharge piping materials include: Chlorinated polyvinyl chloride (CPVC) plastic pipe/tubing. Copper pipe. Cross-linked polyethylene (PEX) plastic tubing.

Do I need an expansion tank on my water heater?

An expansion tank is required on the supply line coming into the tank to reduce the tank stress which will shorten the tank's useful life. An alternative to the expansion tank is an approved pressure relief valve assembly. These devices are required on closed systems, which is public water.

What is the difference between PEX A and PEX B?

PEX A offers higher burst resistance, capable of withstanding up to 500 PSI in extreme cold, while PEX B, being more rigid, is less resilient.

Can PEX tubing be used on heating systems?

Can you use PEX for heating pipes? Yes, As long as you stay within manufacturer's Recommendations and install it properly it will work fine.

Why is PEX failing?

Common Causes of PEX Pipe Failures

In addition, extreme bends and kinks place a very high local stress on the wall of the pipe, making it more susceptible to oxidative degradation. This is especially true in southern climates where water chlorine levels run high.

Can you use PEX on a hot water tank?

For instance, there is no problem connecting PEX tubing directly to electric water heaters. However, with other options, such as a gas water heater, best practices require at least 18 inches of metal piping (corrugated copper or stainless steel) extension from the tank to the PEX tubing.

Will mice eat PEX pipe?

PEX Pipe Is Vulnerable

Rodents Chewing Through PEX Pipe is a common problem in our area. It doesn't matter how old your home is, if you have an attic, you need to watch for rodent damage to PEX Pipe or PVC. If you're hearing rustling noises coming from the attic, it's time to do an inspection.

How many years will PEX last?

The lifespan of PEX pipes is one of their most appealing features. On average, PEX pipes can last anywhere from 40 to 50 years, and in some cases, even longer.

What is the PEX controversy?

The problem with PEX seems to be that it's contaminated -- it leaves the factory with chemicals used in its manufacture still on the pipe. In time it cleans up, but during that time those chemicals are going into the water.

At what temperature does pex pipe burst?

At what temperature will PEX freeze and burst? PEX pipes are extremely burst- and freeze-resistant because of their insulation properties and natural flexibility. However, at certain temperatures, even PEX can no longer stand up to the elements. The temperature cutoff for PEX pipes is around -7°C.

Can you pour boiling water down PEX pipe?

Below is a list of the different materials water pipes are made of and what temperatures they can withstand. The answer to “Can you pour boiling water down your sink drain?” is: If your water pipes are made of Pex, CPVC or PVC – they are NOT made to withstand the temperature of hot, boiling water.

Are plastic PEX fittings ok for hot water?

If you are considering purchasing a good fitting for your pipe, it is better to make use of the plastic PEX fitting as it doesn't easily corrode, it can be used for any water condition and doesn't have fake products like the brass.

Can you use SharkBite for hot water?

SharkBite water heater connectors connect hot and cold water lines and are approved for electric and gas water heaters with a flu vent. They are easy to install and can connect to most pipe types. Pair with HoldRite stout brackets for a secure, easy-to-install connection.

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