black pipe to copper - brass fittings?

awsmith17

I have forced hot water heating.  There is black pipe in the basement and to some of the radiators.  Over the years some of the black pipe to a couple radiators has been replaced with copper.  I'm moving the black pipes to one radiator and would like to replace black with copper since that's easier for me to work with.  It appears that in other locations, where copper has replaced black pipe, brass fittings were used to connect the black pipe to the copper pipe.  They are threaded on the black end and sweat on the copper end.  I can only find these types of fittings in copper.  Am I identifing the fittings correctly as brass?  Can I connect my new copper fittings directly to the black pipe?

The fittings I need are male adapter 1/2'' x 3/4'' and male adapter 1/2''

Thanks.

Alan (California Radiant) Forbes

You can

attach copper directly to the black iron since you have a closed system and the water is free of oxygen.



Those fittings that you have are called copper x male adaptors,  Typically, you see these as wrot, i.e. copper fittings.  I believe they also make them cast  (brass), but they may be hard to find and/or a special order by the box.

Wayco Wayne_2

According to code

you should use brass in between. I often just use a ball valve which in many cases is also useful when servicing the system. WW

Peter Turk

Safest bet is to use a brass fitting

I agree with Alan, but any system filled with potable water will have some oxygen in it. Usually it is negligible, but if your system has any leaks and the water make-up is running often, it could be a problem over time. If you want to cover your butt then use a brass fitting or other type of dielectric protection coupling.



There was a good article in April 2009 ASHRAE Journal by Walter J. Sperko, P.E. The author was a big proponent for chemical treatment in closed loop systems. That is rare and overkill for a residential system, so using a brass fitting will ensure you do not have any dielectric issues.

Ron Jr._3

Closed systems

There is no need to transition from steel to copper using brass . Been piping boilers for 23 years and have seen thousands of boilers transition right to copper with hardly any leaks . Sure you see some leaks on the threaded part of a male or female adapter. But that's due to improper tigthening , unclean threads or heating the fitting after it's tightened ...... in my opinion .  

JIMBO_2

yes, but why

I tend to agree with you, but why do the HIGH-priced architects and city (NYC) engineers insist upon installing di-electric fittings in the heating systems of the schools and colleges we build?  They are closed systems, too.

KevinCorr

architects

...why?... because they don't know anything about pipe.

Peter Turk

Why?

You can appreciate engineers insist on dielectric fittings because it is the safe and smart thing to do even in a closed system. A dielectric fitting doesn't cost much relative to a repair in the future. Think of it as a $40 insurance policy. If there is oxygen in the system, then you will definitely have a problem between copper and black pipe.

Ron Jr._3

Have to disagree Peter

How much water does a typical boiler and piping hold ? Less than 15 gallons ?



How much fresh water will be introduced into a tight hot water system over it's lifetime ?

 

Will a dielectric help where oxidation will occur the most ?  In the boiler itself ? How much oxidation will occur from those 15 gallons ?

 

We routinely remove boilers that are in service 30 , 40 , 50 years . I can't ever remember seeing buildup at a copper by male or copper by female adapter on a closed system .

hot_rod

unions or companion flanges work

well also. I used regular circ pump flanges sometimes, one threaded, one sweat to build an inexpensive "union"



Be sure to watch the temperature limitations if you use plumbing dielectrics on boiler systems.



And no zinc or galvanized fittings, like dielectric unions, in systems that use glycol.



hr



hr

Peter Turk

RonJr: I am referring to schools and commercial buildings

I agree with you RonJr. I was referring to the comment before from JIMBO "but why do the HIGH-priced architects and city (NYC) engineers insist upon installing di-electric fittings in the heating systems of the schools and colleges we build?".

Mark Eatherton

Safe and smart thing to do???

"You can appreciate engineers insist on dielectric fittings because it is the safe and smart thing to do even in a closed system. A dielectric fitting doesn't cost much relative to a repair in the future. Think of it as a $40 insurance policy. If there is oxygen in the system, then you will definitely have a problem between copper and black pipe."



My, and many others experience with dielectric unions (conventional ones, not the flange type) has been less than desirable. They typically leak during periods of time that they are not hot, which induces additional fresh potable water into the system, carrying fresh oxygen with it, causing more degradation of ferrous components than what the unions might have protected.



I've been told that the degree of corrosion on the lesser noble metals is a function of area exposure. In other words, in a systems with LOT of copper wetted surfaces, and just a little ferrous component surface, the ferrous component will degrade at a much faster rate. I have yet to actually SEE said excessive corrosion in a good tight closed loop system, but who am I to question a knowledgeable corrosion engineer.



Architects spec dielectric unions, because that is what they've always done, and it is hard to change old habits.



It has been my, and many others experience, that even in situations where dielectric unions are required by code (DHW tank connections), that the unions actually set up their own electrolytic corrosion cell, causing a part of the union to become so corroded as to nearly close off the water way. Anyone who has pulled a dielectric union off of a water heater, and looked inside, has seen what I am talking about...



IF, and that is a big IF, a dielectric connection is required, yellow brass (red brass carries too much copper) is the preferred way to do it in my professional opinion, and the like opinion of other experienced contractors. It is also an accepted practice by most code authorities.



When engineers Errors and Omissions policies start getting big hits from leaking dielectric unions due to water damage, black mold etc, they MIGHT consider changing their ways. The problem is, all service plumbers KNOW that they will and do leak, and they just eliminate them, without pursuing the party that required them in the first place.



Heaven forbid the insurance companies ever catch on...



ME

Jean-David Beyer

Delectric Unions.

"It has been my, and many others experience, that even in situations where dielectric unions are required by code (DHW tank connections), that the unions actually set up their own electrolytic corrosion cell, causing a part of the union to become so corroded as to nearly close off the water way. Anyone who has pulled a dielectric union off of a water heater, and looked inside, has seen what I am talking about..."



(Remember, I am a homeowner, not a heating contractor.) At one time in my life I used to be an electronics engineer at a small defense contractor, so I know something about this, but I am not licensed to practice any form of engineering.



I considered requesting dielectric unions in my heating system, and concluded that they were useless even if they did not fail themselves due to leakage.



What is a dielectric union supposed to do? It is to electrically insulate the dissimilar metals so an electrolytic battery is not shorted out, causing one of the electrodes to corrode. But consider just one tiny problem in my hot water heating system. A cast iron curculator surrounded by copper pipe. How would I insulate the pump from the rest of the system? I could use a suitable gasket or thick O-ring between the flanges. I would also have to use plastic bolts, or some clever insulation so that the bolts would not short out the circulator to the rest of the system. At first blush, that would seem to work, but it would not because the circulator is grounded to the water pipe by the green wire of its motor. I think I would have code enforcement problems were I to remove the green wire.



The same actually applies to the indirect hot water heater. Imagine a dielectric union in the supply and return from the boiler. That is the typical place to put them. But what good is that, since the union is shorted out because the copper pipe that goes to the boiler and the copper pipe that goes to the domestic water of the DWH are one and the same.



Even the boiler is a problem. It has an aluminum heat exchanger, and steel pipe. This is connected with steel pipe and fittings, but the Pressure Relief valve is brass. The rest of the pipe are copper, but a C.I. FlowCheck valve is in there.



The "sneak" grounding paths in these systems seem to me to make dielectric isolation in these systems impossible as a practical matter. So it is either bronze all the way, or put up with some electrolytic action. I would avoid using zinc pipe in a copper system, but as far as I know, there is no such thing. I guess galvanized would be about as bad.



As far as bronze all the way is concerned, anyone know of a bronze indirect hot water heater? (This is not a serious question.) Mine is of the tank within a tank type. The inner tank has the domestic hot water in it and is stainless steel. The outer tank is regular hot water heater steel. By themselves it might be OK, but copper pipe in and out, brass P/T valve, brass valves nearby (drain, purge, air eliminator).



I choose to believe that as long as I do not have leaks, and do not

flush the water from the system annually (as the previous homeowner

suggested to me, but I ignored) that I may be OK. And I cross my

fingers.

HankPank

Use of Dielectrics

Hi, Let's not forget one of the basics we all learned in school lab which is the basis for using a "proper" plumbing dielectric union. 

   When 2 dissimilar metals are placed in any liquid which has even the slightest acidity then they will become a "battery" and a small electric potential is produced. Slight current flow will occur, thus causing the process of electrolysis (copper plating) to take place At Some level, if there is a complete circuit (your pipes) for the current to flow.

 Water is naturally slightly acidic and boiler water will build up a higher level thru time without chemical additives. A quality Rubber Insulated Union used for plumbing will break the "circuit" thus preventing the current flow.

 This more so  Prevents "pinholes" from occurring in your piping over many years and has less to do with "leaky threads" from poor  assembly practices.

 True Dielectric (non insulators) couplings and  nipples sometimes used improperly work on different principle where their molecules align opposite and retard or prevent current from flowing thru "Polarization" and yes, like a magnet they will pick up the iron and  will clog with time. You must use the fully insulated type union for proper results.

   

SWEI

boiler water will build up a higher level thru time

other than oxygen ingress, I can't see a mechanism which would cause this.  We install ball drains or union ball drains at most material transitions anyway, so there's brass in the middle.



Like Mark, I've seen enough issues with dielectric unions that I prefer

to avoid them whenever possible.  Nonmetallic pipe is used for so much

potable water these days that it's eliminated many of the challenges we

used to encounter.

icesailor

Specifications:

Because the Architects spec out the mechanicals to a Mechanical Engineer who uses programs with templates that haven't changed since computers were first being used. They usually get a percentage of the contract price.

If you want a straight Copper X Male of Female, you will almost only find wrought copper fittings. If it is a reducing adapter, like a 1 1/4" FPT X 3/4" Copper, it will be cast because it is cheaper to tool up the reducing adapter and so little demand. Where the straight non reducing size is common.

Any mechanical draftsmen working for a mechanical engineering firm wouldn't know that there is a difference.

And if you needed to silver braze the fitting, it must be wrought copper. Id it needs to be reduced, you use copper reducing couplings.

Use Teflon Tape and a quality paste like Rectorseal #5 or Rectorseal #100 or any other popular brand, and properly done, there is no reason for a leak. Not ever.

YvonneB

Does anyone have anything in writing?

I am presented with my newest "promotion" to outside sales for a local Wholesaler.  This question was posed to me today.. again.  Before my wholesale career I was an installer for 20 years.  I never used dielectric unions in a closed loop system with the proper tubing installed.  Does anyone "Dan" have anything in writing!!!!

I have a large customer that has a new employee who was taught like me and is trying save the company lots of $$$ on a project.  All I have to do is show it to them in writing of an official document or training book!!

All help is appreciated!

Unknown

die eclectric unions

Die-electric unoins have no business on heating and plumbing systems, period..

icesailor

I think you must:

And they think that you MUST.

It says somewhere in a book with Specifications all spelled out for them.

Like that song in The Wizard Of Oz about "If I only had a brain".

YvonneB

black pipe to copper

I agree but I need it in writing!

icesailor

Here's the problem:

Here's the problem, someone, somewhere has stated (or) "It is written,,,"

that you need dialectic unions. Once that empirical proclamation is made, it becomes a Gospel.

I once installed a heating system in a barn and residence. There was supposed to be a "listed" hour fire rated wall between the hay storage and the residence. The carpenter didn't install it properly. It was an extremely difficult and expensive fix. Although 2 layers of 5/8" fire code sheetrock would equal the 2 hour rating, a solid 12" would NOT. A 4" concrete partition block wall would give you the listing but 12" of fire code would not. Because no one had ever paid for and tested a 12" sheet rock wall.

If the manufacturer of XYZ Dialectic Unions pays to get their unions listed, They need a ROI, Return On Investment.

YvonneB

Dielectric in Hydronics

To you all,

I agree with the "dead water", no oxegon and no reaction!!  I have lived it and practiced it!! The people I am dealing with want to see it in writing!

YvonneB

black to copper

Mr. Dan, it is time to chime in!!  I have practiced "pumping away", "Lost art of Steam Heating"; "primatary/ secondary" and soooo much more....  Need you!

nicholas bonham-carter

She said-he said

If the dialectic unions can be left out of the installation, then as a result the piping should be inspected more frequently, (even more frequently if the D-unions are in place!)--NBC