Plumber at my sister’s house put in a couple of hose bibs. In several spots, the copper pipe is making firm contact with a steel electrical pipe. Is this likely to cause a dielectric reaction and a leak down the road? Is shoving a piece of cardboard or pipe insulation in between the pipes sufficient to prevent this problem? Does a good plumber let his pipes come in contact with steel?
Replies
It wouldn't be dumb to shove something between the two (I'd use a chunk cut from a plastic milk carton or some such). However, since it's a (relatively) dry contact there isn't a whole lot of likelihood of problems.
I've never come across a good plumber, so I couldn't answer your last question. (Ducking!!)
Oh, water is a factor? My only experience with this is a major flood caused by a galvanized plug that was put in a threaded copper fitting in a remodel ten years earlier. One day, the plug just blew out and I was told the threads had rotted away due to the dialectric reaction. But this pipe was filled with water under pressure all those years.
Now that you mention it, I have never been thrilled with any plumbers I have used. Do the good ones go to commercial work where the money is better?
"Do the good ones go to commercial work where the money is better?"
Yes. Without a doubt.
I am one of the luckiest guys on the face of construction... I have a commercial plumber that does my residential stuff on the side. Saves my customers soooo much heartache and is better than Pepto for my stomach. Never had to make a single change on anything the guy has ever done (knocking wood).
On the problem..... A piece of pipe insulation will avoid knocking... but use hard plastic as a permanent barrier. I really like the idea of the piece of milk jug... brilliant! Put it on the outside of the foam insulation, IMO.
Perhaps a short length of PVC pipe sized to fit over the foam insulation. It could be slit up the side with a hacksaw and held in place with lashings of nylon cord or perhaps a tie-wrap either side of the contact area.
If the location is a basement or other humid area, there could be a fair amount of conensation on the cu, enough to start problems.
Jon Blakemore
IMHO these inadvertent connections could pose a safety problem, circulating currents and ground path issues, and is disallowed by the NEC. It could also cause intermittent noise, electrical and acoustic, problems on both systems. I would think that short sections of foam pipe insulation placed to keep the pipes and conduits segregated would be a good idea. It the very least it would keep the two systems from physically rattling together when a faucet is shut quickly. This alone could cause a plumbing leak given enough time.
Doesn't sound like this installation was this plumber's finest hour. Not the end of the world but not sterling technique, IMHO, either.
I consider her Plumber a sloppy, untaught installer. Its instaltion like that that causes water hammer. Grab the pipe and shake it, that will give you a preview of how noisy the pipes will be.
Soooo....... how would this cause water hammer??????
When a "Plumber" installs pipes that touch other pipes, it will rattle and make loud noise 'cause it bounces of the other object.
I get crossed eyed looks when I insist that copper runned thru a house shall not touch any other metal, be clamped directly to ceiling joists, have wood wedges in the bored hole, be hung by plumbers's tape, be held by framing nails OR "J" hooks.
There are a few good plumber who can work THE right way, the rest dont understand or care why their pipes rattle, bang and creak behind the walls and ceilings. The solution of air chambers and pressure regulators doesnt always solve the problem.
While I won't dispute improper installation, none of what you describe causes water hammer.
Maybe what I describe is not clear. Water Hammer IS caused by loose, unsecured pipes. How do I convince you or explain it to you, without offending or belittling. I have eliminated the banging noise by wrapping the copper with carpet padding, rubitex, felt or black refrigerant line insulation and then clamping it down. Water hammer happens when the water flow is quickly shut off, which causes the pipe to jump or jerk. This jerk of the pipe will rattle or bang any object it is touching loosely. If you hear the water pipes singing in the walls, its because there is direct contact with the wood in the walls. I can stop water hammer under a house and in the attic, its harder in the walls.
I have grown up with old timers who knew this, now I'm an oldtimer who see these young guys who have no clue.
To others reading this, am I clear? Its all logical to me.
I think the disagreement is in the definition of water hammer. To the person disagreeing with you, water hammer is when the water bounces back from a quickly closing valve and makes the pipe jump around. To you, water hammer is when the jumping pipe bangs into things. From your point of view, if the pipe doesn't make any noise, the hammer is gone. From his point of view, if the pipe moves at all, it's still water hammer, even if it no longer makes any noise.
Your explaination sounds logical.
In fact, I would say that you have water hammer even if there's no motion at all in the pipes, and no noticeable sound. The quick shutoff causes a pressure surge in the pipes and stresses the joints, potentially leading to failure in extreme cases.
Grin.... I was just curious. No offense taken or given.
There are 4 common causes of noisy pipes.
Water hammer is caused when water travelling at high velocity stops suddenly and has nowhere to go when the shockwave goes through the system.In this case, hammer arrestors may be a good idea. The shockwave amplifies the pressure 10 to 15 times which can create some real messes.The sound is usually one or two loud bangs.
Chattering pipes are usually caused by loose tap washers and the pipes literally chatter.
Howling or vibrating pipes are usually caused by a diaphagm style valve closing slowly with not enough water flow through the valve. Toilet ballcocks,urinal and toilet flush valves and irrigation valves are bad for this.
All three of these noises will occur even if the pipes are installed properly, but are worse if they are not.
The fourth (and to me the most annoying)noise is ticking.This is caused when the pipe expands and contracts due to expansion and is caused by improper installation.
Plastic and copper drainlines can also tick,
That ticking noise sounds like dripping to some homeowners, they occur mostly with those red rubber coated copper hooks.
We know what a bad installation is, I'm no Plumber, wished the so called ones knew more than me.
You've got a potentially dangerous chafing situation there -the copper pipe will last about 6 mo if you do nothing. I would even bet that its already pretty shiny at the contact point. The best solution, but not the easiest, would be to physically separate the cu and the emt.
Eric S.
If the pipes are in "firm contact" with one another, i'd guess Sis doesn't have a lot of room for foam and PVC pipe to place between them. Also, the foam won't hold up in a load-bearing situation and constant rubbing on it will wear through it eventually. I don't know if it's hydrophilic in its own right, for that matter.
Might i suggest a wrap of something like EPDM, the roofing material? Easy...a piece of inner-tube would be a cheap, simple, and durable fix for this situation, and it wouldn't take up much space.
A good plumber does not.
In our church there were copper pipes hard pressed against one another. It took 15 years, but the motion of expansion and contraction wore a nice hole in one of them. The wear pattern is quite flat, so when the hole goes it opens up quite large all in one shot.
Thanks for the good advice, everyone.