The diaelectric union has the purpose of preventing corrosion that occurs between two dissimilar metals, such as copper pipe joined to galvanized pipe in a water supply system. In such circumstances the corrosion occurs at the point of contact between the two dissimilar metals.

Why do you need dielectric unions?

Dielectric unions are used to separate two dissimilar metal pipes (such as copper pipes and galvanized steel). Purpose of dielectric unions is to prevent galvanic corrosion, which is caused by electrolysis.

Are dielectric unions necessary on a water heater?

Dielectric Unions

If either the tank nipples or the pipes are galvanized steel, however, and you are connecting them to copper, you must use a fitting called a dielectric union to make the connection. ... Both the hot and cold water pipes must have this fitting -- it's a code requirement.

Do Rheem water heaters need dielectric unions?

Re: Rheem says: dielectric not necessary! Interesting. They must mean that a dielectric union is not required to prevent problems with the water heater. However, no dielectric union between dissimilar metal connections will likely result in failure of the piping at that point.

Do you need dielectric union for copper to brass?

Brass is a copper/zinc alloy, so a brass nipple qualifies as a type of “copper alloy fitting” that is cited as acceptable by the code. While a dielectric union (shown above) provides a break in electrical conductivity that theoretically would be best, most plumbers prefer a brass fitting.

The importance of Dielectric unions

36 related questions found

Do dielectric unions leak?

A dielectric union is a plumbing fitting that is meant to join two dissimilar metal pipes so they don't experience a galvanic reaction and begin to rust. ... We find many dielectric unions that have started to rust which will eventually lead to a water leak if not remedied.

Should I use Teflon tape on brass fittings?

In general, Teflon tape is recommended to be used on most threaded connections that do not have a rubber gasket. If you're inquiring about brass fittings, Teflon tape is only necessary if there isn't already a built-in rubber seal.

Are SharkBite fittings dielectric?

The standard SharkBite fittings (i.e. Coupling, Elbow, Tee) cannot be used as a dielectric union. However, SharkBite Stainless Steel Braided Flexible Coupling Hoses can be used as a dielectric union.

Where are dielectric unions required?

In most jurisdictions plumbing codes require the use of a dielectric fitting when joining steel piping to copper or other metals; some plumbing jurisdictions permit use of a 6-inch brass nipple in this location as an alternative to diaelectric fittings.

Is a heat trap necessary?

Do I Need a Heat Trap on my Water Heater? Using either a heat trap loop or heat trap nipple can reduce wasted heat by as much as 60 percent. That really adds up when the bills come in. In addition, many state and local ordinances now require heat traps.

Is it OK to use galvanized pipe for water heater?

Thanks. Black steel is the prefered pipe material, followed by copper. Galvanized should not be used. Galvanized Pipes in a Hot Water Heating System.

Do I need a dielectric union for brass to galvanized?

There is some controversy as to the effectiveness of dielectric unions, but the bottom line is that if you connect a copper pipe to a galvanized one, some plumbing inspectors are going to require one. Certain municipalities consider a brass fitting a suitable dialectic union, but others do not.

Why do dielectric unions fail?

every single union fails miserably by either leaking, clogging up completely, rusting to pieces with no water contact outside pipe or depositing rust in water.

Will stainless steel and copper cause electrolysis?

If Copper is connected to Stainless steel Type 304, then the copper will corrode to sacrifice to the stainless steel. ... The most serious form of galvanic corrosion occurs in plumbing or HVAC piping systems that contain both copper and steel alloys and are filled with water (an electrolyte).

Is copper OK for brass?

To safely connect copper and galvanized steel, you have two options. Since brass doesn't react with either the copper or the zinc, one method is to make sure you have a threaded female end on both the copper and the steel pipes, and then connect the two by simply inserting a short threaded brass nipple between them.

Can you put stainless steel and copper together?

While stainless steel is a common plumbing material for water mains and fittings because it has an exceptionally long lifespan and is resistant to corrosion, it's not a good idea to directly connect stainless steel to copper. This is because stainless steel and copper are actually dissimilar metals.

Is it OK to connect brass to stainless steel?

Using brass fittings on stainless steel tubing is not recommended. Brass is softer than steel and may not seal onto the tubing as well, risking leaks. You might also see galvanic corrosion, which is a process where the corrosion is accelerated by 2 dissimilar metals contacting one another.

Does brass stop electrolysis?

Dielectric unions are commonly used around commercial and residential water distribution systems to avoid electrolysis and deterioration in the piping systems. ... Threaded brass is widely used for fittings for copper pipe and brass connectors of any kinds are used in the repair industry.

Why are SharkBite fittings illegal in California?

CA has a powerful plumbing lobby and they don't like homeowners having access to easier products. CA has strict anti-lead legislation where many brass fixtures still contain a percentage of lead.

Are Sharkbites reliable?

Fact: Contractors who use SharkBite find it to be a dependable and safe solution in concealed spaces, including behind the wall and underground. For example, Clint McCannon, owner of Cannon Plumbing, used SharkBite PEX and EvoPEX to repipe an entire home, with no concern about failed fittings or leaks.

How long will SharkBite fittings last?

How long do SharkBite fittings last? SharkBite fittings last a long time. In fact, SharkBite warrants the fittings for 25 years when used with SharkBite tubing.

Why are my brass fittings leaking?

Pipe Joint Compound for Leaking Brass Fittings

Connections that involve threaded fittings and pipes are susceptible to leaks if they are not properly sealed with either Teflon tape or pipe joint compound.

How many times do you wrap threads with Teflon tape?

You always want to wrap seal tape around threaded pipe fitting in a clockwise direction. In most cases for a new joint you should apply only two or three wraps of tape. On older fitting where the threads may be damaged you may consider adding a few more wraps, but keep the number of warps to a minimum.