Black pipe to copper – brass fittings?
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”
Black pipe to copper brass fittings
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.
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.
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.
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…
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