Can you connect galvanized to PEX?

Connecting galvanized pipes to PEX (cross-linked polyethylene) pipes is possible but not always recommended. There are a few factors to consider when deciding whether to join these two different pipe materials.

The Differences Between Galvanized and PEX Pipes

Galvanized pipes are made of steel pipes that have been coated with a layer of zinc. The zinc coating (galvanization) protects the steel from corrosion. Galvanized pipes were commonly installed in homes in the first half of the 20th century.

PEX is a flexible plastic piping material that is commonly used for water supply lines today. It is made from high-density polyethylene that has been cross-linked to improve temperature resistance and prevent potential leaching of chemicals into the water.

Here are some key differences between galvanized and PEX pipes:

Pipe Material	Galvanized	PEX
Composition	Steel coated with zinc	Cross-linked polyethylene plastic
Common Sizes	1/2″ to 2″	1/4″ to 1″
Pressure Rating	Medium	High
Temperature Rating	Medium	High
Flexibility	Low	High
Corrosion Resistance	Medium – zinc coating delays corrosion	High – plastic does not corrode
Ease of Installation	Difficult – rigid pipes	Easy – flexible pipes

As you can see, galvanized and PEX have quite different properties and are used in different applications. Galvanized pipe is rigid while PEX is flexible. PEX has a higher pressure and temperature rating. And PEX offers better corrosion resistance.

Can You Connect Galvanized to PEX Directly?

Galvanized and PEX pipes cannot be connected directly to each other. There are a few reasons why:

• Different materials – You cannot connect inflexible galvanized steel directly to flexible PEX plastic.
• Different sizes – Galvanized pipes are usually at least 1/2″ while PEX is commonly 1/4″ to 1″. The size difference makes direct connections impossible.
• Threading – Galvanized pipes have threaded ends while PEX uses compression fittings. The different connection methods are incompatible.
• Expansion and contraction – PEX expands and contracts with temperature changes. Rigid galvanized does not. Direct connections could lead to leaks.

For these reasons, you need to use an adapter or transition fitting to connect galvanized and PEX plumbing.

Transition Fittings for Connecting Galvanized to PEX

There are two main types of adapters used to join galvanized and PEX pipes:

PEX-to-Threaded Fittings

These fittings have a PEX end with a compression connection on one side and male threaded end on the other. The threads allow the fitting to be screwed into a female threaded galvanized pipe fitting.

Steps to connect:

1. Cut the PEX pipe end square and slide a PEX compression ring over the end.
2. Insert the PEX pipe into the compression fitting end of the adapter.
3. Use PEX crimping tools to crimp the compression ring over the pipe.
4. Apply thread sealant tape to the threaded male end of the adapter.
5. Screw the threaded end into the galvanized pipe fitting.

This type of connector allows a direct transition from PEX to galvanized pipes. The fittings come in a variety of sizes.

Threaded-to-PEX Fittings

These fittings have male threaded ends on one side to connect to galvanized pipe and a compression end to connect to PEX on the other.

Steps to connect:

1. Wrap thread sealant tape around the threaded male end.
2. Screw the threaded end into the galvanized pipe fitting.
3. Slide a PEX compression ring over the PEX pipe end.
4. Insert PEX pipe into compression fitting end.
5. Crimp the compression ring using PEX crimp tools.

This style of fitting is handy when adapting an existing galvanized plumbing system to use new PEX pipes.

Using PEX-to-Copper-to-Galvanized Connections

Some homeowners choose to transition from PEX to copper pipes first using a PEX-to-copper fitting. Then they use a copper-to-galvanized fitting to complete the connection. This provides an additional flexible joint.

The steps involve:

1. Connect PEX to copper with a PEX-to-copper compression fitting.
2. Connect copper to galvanized with a copper-to-galvanized threaded transition fitting.

A coupling option is to connect the copper and galvanized pipes using a dielectric union fitting. This electrically isolates the two dissimilar metals.

Things to Keep in Mind When Connecting Galvanized and PEX

Here are some tips when joining galvanized and PEX plumbing:

• Use only transition fittings designed for this purpose. Do not try to directly connect galvanized and PEX.
• Galvanized pipe ends must be threaded and in good condition. Re-tap or replace sections with damaged threads.
• Support pipes properly to avoid strain on the joints.
• Avoid connecting galvanized and PEX plumbing in areas where pipes could freeze. The inflexible galvanized can crack from PEX expansion.
• Make sure to pressure test for leaks after making any new plumbing connections.

In most cases, it is better to replace old galvanized plumbing completely with new PEX lines if possible. But transition fittings enable connecting small sections of galvanized when needed.

PEX-to-Galvanized Conversion Adapter Kits

There are conversion kits available that include multiple PEX-to-galvanized transition fittings and allow converting entire plumbing systems from galvanized to PEX.

For example, the Apollo PEX Galvanized Conversion Kit includes:

• PEX-to-threaded male adapters
• PEX-to-threaded female adapters
• 1/2″, 3/4″, and 1″ sizes
• 20 fittings total

With one of these handy kits, you can switch the water supply lines from old galvanized to new PEX piping. The fittings allow connecting the new PEX to existing galvanized fixtures, valves, and pipe ends.

Hiring a Plumber

While do-it-yourselfers can connect galvanized and PEX plumbing in some cases, it is often advisable to hire an experienced plumber for the job.

A professional plumber has the knowledge, tools, and skills to:

• Determine whether transitioning from galvanized to PEX is feasible or if full replumbing is needed.
• Select the proper transition fittings.
• Properly cut and join the pipes.
• Avoid leaks and other problems down the road.

Trying to save money by tackling a galvanized to PEX plumbing transition yourself can sometimes lead to headaches and costlier repairs later on. Hiring a reputable plumber ensures the job is done right the first time.

Conclusion

Joining galvanized and PEX plumbing requires using proper adapters or transition fittings. While direct connections between galvanized and PEX are not possible, using threaded transition fittings allows adapting some galvanized components to work with a new PEX supply system.

When undertaking any plumbing project involving mixed materials, it is wise to educate yourself on the proper techniques and components. And hiring an experienced plumber is highly recommended to ensure correct installation and prevent potential problems.