Thread: Dielectric fittings

Does a water heater have to have dielectric fittings when the nipples on the water heater are brass? Are there other metals used for the nipples that do not require dielectric fittings?

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Originally Posted by Gary Mohel

Does a water heater have to have dielectric fittings when the nipples on the water heater are brass? Are there other metals used for the nipples that do not require dielectric fittings?

Brass - NO
Other materials used for nipples that do not require dielectric fittings - Cannot think of any at this time but it's still early in the morning.

Gary,
If the nipples are brass then I don't believe you will need dielectrics. The brass nipple can accommodate either galvanized or copper (or plastic) supply piping.

RJDalga
Home Analysts
Kalamazoo, MI

Most codes state that when joining different metals to use a brass fitting for the transition or a dielectric union. Now one thing that many forget is that most codes also state that a union must be used on a water heater as well. I see many guys put brass nipples on the tank with female adapters and solder the pipe right up with out any union what so ever. What I normally do if I do not use a dielectric union is brass IPS unions on galvanized nipples.

Originally Posted by Ron Hasil

Now one thing that many forget is that most codes also state that a union must be used on a water heater as well.

The IRC does not require unions.

If you are thinking of this section as requiring unions ... (underlining is mine)
- P2801.3 Location. Water heaters and storage tanks shall be located and connected to provide access for observation, maintenance, servicing and replacement.

... then that section would not allow water heaters in attics.

Replacement of a water heater in an attic is much more difficult than replacing a water heater by cutting the lines and then coupling them back. No union is specified.

Originally Posted by Jerry Peck

The IRC does not require unions.

If you are thinking of this section as requiring unions ... (underlining is mine)
- P2801.3 Location. Water heaters and storage tanks shall be located and connected to provide access for observation, maintenance, servicing and replacement.

... then that section would not allow water heaters in attics.

Replacement of a water heater in an attic is much more difficult than replacing a water heater by cutting the lines and then coupling them back. No union is specified.

Sorry Jerry,

I should of said Illinois plumbing code and maybe other codes require unions on the water heater. underlining by me.

Section 890.350 Unions

Unions may be used in the drainage and venting system when accessibly located above ground. Unions shall be installed in a water supply system within 5 feet of regulating equipment, water heaters, water conditioning tanks, water conditioning equipment, pumps, and similar equipment which may require service by removal or replacement. Where small equipment may be unscrewed, only one union shall be required.

a) Drainage System. Unions may be used in the trap seal and on the inlet and outlet side of the trap. Unions shall have metal to metal seats except that plastic unions may have plastic to plastic seats.

b) Water Supply System. Unions in the water supply system shall be metal to metal with ground seats, except that plastic to metal unions may utilize durable, non-toxic, impervious gaskets. Unions between copper pipe/tubing and dissimilar metals shall either be made with a brass converter fitting or be a dielectric type union.

Originally Posted by Gary Mohel

Does a water heater have to have dielectric fittings when the nipples on the water heater are brass? Are there other metals used for the nipples that do not require dielectric fittings?

If the tank is galvinized steel or steel you cant attach a brass nipple. The 2 different metals will corrode each other. You should use a galvinized nipple in the tank and a galvinized/brass dielectric union.

Michael

Originally Posted by MichaelKershner

If the tank is galvinized steel or steel you cant attach a brass nipple. The 2 different metals will corrode each other. You should use a galvinized nipple in the tank and a galvinized/brass dielectric union.

Michael

Brass is considered compatible with steel and can serve as a dielectric fitting between copper and steel, which includes the tank.

Now, if one wants to get more technical about it, then it depends on the type of brass or bronze and the type of steel as some are more compatible with each other than other types.

The above said, though, for plumbing piping systems in a building, especially in a dwelling unit, brass (lumping all types of brass and bronze together) is considered compatible with steel (lumping all types steel together) for the purpose of stopping/reducing galvanic corrosion (the reason for dielectric fittings are required).

In chemical plants, the compatibility of the metals much be very closely matched, and in those cases brass and bronze are not considered compatible with steel.

Thus the answer becomes a question: What is the system to be used for? Potable water? If the water is of a quality to be considered potable water, then brass and bronze would be compatible with steel.

Just to chime in on dielectric unions. it has been my experience as a plumber for many years that dielectric unions will rust out within a year or two. I always used 6" brass nips for water heater hooks.

Brass is considered a dielectric fitting of sorts. It creates enough of a buffer between the steel in the tank and the copper water pipe to prevent electrolysis.

Brass and copper are compatable to each other. Steel attached to brass or copper will create electrolysis and corossion will occure. Dielectric unions are separated with rubber gaskets. You can use a steel X brass dielectric union to prevent problems. The steel 1/2 of the union gets attached to the steel nipple coming out of the steel tank and the brass 1/2 of the union gets attached to the house copper or brass piping.

Originally Posted by R. A. Wilkins

Brass is considered a dielectric fitting of sorts. It creates enough of a buffer between the steel in the tank and the copper water pipe to prevent electrolysis.

Correct.

The tank will fail prematurely if brass nipples are used, particularly if there is a hard water condition, based on my experience. What do manufacturer instructions stipulate? What about trapper nipples, which have dielectric waterways? These help conserve energy, too. The best installations that I have seen, from a standpoint of low corrosion when dealing with dissimilar metals, are trapper nipples at the tank, dielectric or brass unions, and then copper tubing.

My experience

Brass nipple, almost never any corrosion for years down the road.

Galvy, as little as a year or two and they should be changed out no matter what type of connection between the galvy and copper

Thank you Randy Aldering findly someone understands. I have been in the boiler and plumbing industry in NY for 25 years and each time i saw a steel or cast iron boiler with a brass or copper water feed line connected directly to the boiler there was corrosion causing premature failure. At that point repair (cut out the corroded piece of steel and weld a new piece or change the cast iron section) is necessary to prevent leaks.
What is a trapper nipple - is it coated on the inside?

Thanks
Michael

Originally Posted by MichaelKershner

What is a trapper nipple - is it coated on the inside?

That would be a heat trap.

They are rated for use as a dielectric fitting.

Perfection Corporation-Heat Trap™ Fittings