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Perhaps there's some other magic at work, I don't know, but before you dis mystatement observations and experience, go change a couple thousand waterheaters including gas fired and electric and get back to us.Doug

>It is far wiser to spend the money and time checking the >sacrificial anode rod every couple of years and replacing >it when it is badly corroded.

> On 11/08/03 Jeff Wisnia jwi...@conversent.net writes in part:>> >I heartily disagree with you on your technical reasoning.>> I didn't give any technical reasoning only what I've observed in over 30 years> of plumbing service.

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

>>> Perhaps there's some other magic at work, I don't know, but before you dis my> statement observations and experience, go change a couple thousand water> heaters including gas fired and electric and get back to us.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

I didn't give any technical reasoning only what I've observed in over 30 yearsof plumbing service. Frankly your experience with your one electric water heater is prettyinsignificant compared to the number of water heaters I've changed out that hadbrass nipples screwed into the black tank with no significant build-up ordamage to the copper tubing.Labratory test are all well and good to give an indication of anticipatedresults but quite often fields results vary dramatically from lab results.Ask the other plumbers who visit here from time to time if a brass nipple doesa better job than a dielectric union to help control the effects ofelectrolysis

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The "did" was, as I stated, disagreement with what you said, not disrespect of themor you. I'm sorry if you misunderstood that, but a lifetime of experience hasshown me that there's there's probably little I can do to change your mind aboutthat now..Jeff

Frankly your experience with your one electric water heater is prettyinsignificant compared to the number of water heaters I've changed out that hadbrass nipples screwed into the black tank with no significant build-up ordamage to the copper tubing.Labratory test are all well and good to give an indication of anticipatedresults but quite often fields results vary dramatically from lab results.Ask the other plumbers who visit here from time to time if a brass nipple doesa better job than a dielectric union to help control the effects ofelectrolysis

Go to the site below and you'll see that, since iron is higher in the galvanicseries than copper or brass, corrosion attacks the iron, not the copper. (Zinc iseven higher in the table than iron, that's why they use zinc anodes, which corrodeand "protect" the iron tank.) You'll also see that brass is right next to copper inthe series, so there shouldn't be much difference if it's used as you described.http://www.mcnallyinstitute.com/CDweb/g-html/g002.htmIf you can honestly state that all of the tanks you've changed which had brassnipples between them and copper piping had insignificant buildup or damage to thecopper tubing AND all the ones you've changed in the same town which didn't havebrass nipples had significant buildup or damage to the copper tubing, then I'llapologize to you a second time.

I totally agree with the above statement, however the original question didn'tmention anything about water heaters. I only used water connections fromcopper piping to brass nipple to the black tank in a storage water heater, asan example of what I've observed. Perhaps there's some other magic at work, I don't know, but before you dis mystatement observations and experience, go change a couple thousand waterheaters including gas fired and electric and get back to us.Doug

>>> >It is far wiser to spend the money and time checking the> >sacrificial anode rod every couple of years and replacing> >it when it is badly corroded.>> I totally agree with the above statement, however the original question didn't> mention anything about water heaters. I only used water connections from> copper piping to brass nipple to the black tank in a storage water heater, as> an example of what I've observed.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

Absolutely, but the tanks you've changed out were not in *my* basement, where theywere subjected to the water in our town.And, FWIW, I'd gone through two heaters in this house in twenty years prior tousing those dielectric unions when installing the third heater. There was NObuild-up or damage to the copper tubing or fittings at the tank in all that time.Go to the site below and you'll see that, since iron is higher in the galvanicseries than copper or brass, corrosion attacks the iron, not the copper. (Zinc iseven higher in the table than iron, that's why they use zinc anodes, which corrodeand "protect" the iron tank.) You'll also see that brass is right next to copper inthe series, so there shouldn't be much difference if it's used as you described.http://www.mcnallyinstitute.com/CDweb/g-html/g002.htmIf you can honestly state that all of the tanks you've changed which had brassnipples between them and copper piping had insignificant buildup or damage to thecopper tubing AND all the ones you've changed in the same town which didn't havebrass nipples had significant buildup or damage to the copper tubing, then I'llapologize to you a second time.

> Frankly your experience with your one electric water heater is pretty> insignificant compared to the number of water heaters I've changed out that had> brass nipples screwed into the black tank with no significant build-up or> damage to the copper tubing.

While it will NOT meet UPC code requirements, in my experience a brass nippledoes a pretty good job of electrically isolating the black tank of a waterheater from copper tubing.I suppose it would work just as well for a galvanized to copper connections asthe material in galvanized or black you're trying to isolate the copper from isiron.Doug

Theory is great, but theory is tested in practice. Science doesn't discovertruth. The most science can do is come up with a hypothesis that fits for atime. You won't convince plumbers that engineers and architects have allthe answers. We've seen too many so-called "engineered" designs thatweren't worth a damn.MM

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> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

If you can find any licensed electrician you know who'd agree with your statementthat brass, a metal which is a very good conductor of electricity, could possiblyelectrically isolate two other metal items, then I'll offer a full apology to you.

Labratory test are all well and good to give an indication of anticipatedresults but quite often fields results vary dramatically from lab results.Ask the other plumbers who visit here from time to time if a brass nipple doesa better job than a dielectric union to help control the effects ofelectrolysis

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--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

You've got it right, but what I was trying to say in my OP was that the "contact" doesn't have to be directly between thetwo metals touching each other. The electrolytic corrosion takes place just as badly if they are connected together by someother electrical conductor.If you stick the bottom ends of a zinc and a copper rod in a glass jar of saltwater, you won't get much corrosion ifthey're not touching each other, but connect the top ends with a piece of wire (even one a hundred feet long) and watch howmuch faster the zinc corrodes.Remember the old zinc/carbon flashlight batteries, and how they'd leak and ruin your flashlight if you discharged them toomuch? That happened because the zinc shell got eaten through by the galvanic corrosion which took place when you connectedthe carbon to the zinc through the flashlight bulb.That's why I was barfing about dielectric unions helping only if there isn't a "sneak path" for electric current to flowaround the insulating gap in those unions.Jeff

I tried my best not to offend you, but the "technical reasoning" I choked over wasyour statement that:"in my experience a brass nipple does a pretty good job of electrically isolating

Rheem Pro series WHs have dielectric nipples preinstalled. They also offeran extended warranty kit which consists of an extra anode rod attached to aพ" dielectric nipple which installs in the hot side tapping. But get this;Rheem gives you a brass, พ" x 1" bushing for WHs with 1" tapings.So, what's up with all of this? Is the key to always use dielectric nippleswith dielectric unions? Is it just as well to connect directly to the WHwhether it's copper, brass or steel? Does it all depend on water andelectrical conditions in a particular house and area?As far as I'm concerned the jury is still out on DEUs. As I said earlier, Ihaven't seen where they are making much difference and I haven't seen whereit makes much difference whether it's an electric, gas, or oil fired WH.~C~

So, what's up with all of this? Is the key to always use dielectric nippleswith dielectric unions? Is it just as well to connect directly to the WHwhether it's copper, brass or steel? Does it all depend on water andelectrical conditions in a particular house and area?As far as I'm concerned the jury is still out on DEUs. As I said earlier, Ihaven't seen where they are making much difference and I haven't seen whereit makes much difference whether it's an electric, gas, or oil fired WH.~C~

Yes, but the OP has since posted that wants to use dielectric unions to separatingold iron plumbing in the walls of his home from new copper in the basement/crawlspace. I maintain that he'll have to bypass those couplings with an electricaljumper to maintain the code required grounding of the pipes and fixtures in thehome. When he does that he'll lose any help those dielectric unions might havegiven him Thge steel parts of those unions and the iron pipe adjacent to them willsuffer from corrosion.

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> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

I replumbed everything with copper and copper unions. I think it's better to letthe copper run righ to the tank ports, so that the galvanic currents have a bettershot at working on the sacrificial anode.I sliced the leaking nipple open. You can see it at:http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

Remember the old zinc/carbon flashlight batteries, and how they'd leak and ruin your flashlight if you discharged them toomuch? That happened because the zinc shell got eaten through by the galvanic corrosion which took place when you connectedthe carbon to the zinc through the flashlight bulb.That's why I was barfing about dielectric unions helping only if there isn't a "sneak path" for electric current to flowaround the insulating gap in those unions.Jeff

The drain valve and the T&P also dont have a direct connection toground.Galvanic corrosion is most common in copper distribution systemsconnected directly to the steel water heater tank and to the waterservice piping under ground which provides the ground for the circuit.Then the electrician comes along and compounds the problem byconnecting the electrical service ground to the incoming servicepiping.....

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

http://www.mcnallyinstitute.com/CDweb/g-html/g002.htmIf you can honestly state that all of the tanks you've changed which had brassnipples between them and copper piping had insignificant buildup or damage to thecopper tubing AND all the ones you've changed in the same town which didn't havebrass nipples had significant buildup or damage to the copper tubing, then I'llapologize to you a second time.

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

usually when doing a basement changover and leaving the galv. risersI'd either use a diletric union, a brass ips valve or a min 3" brassnipple. I haven't had any problems over the last 30 years. A simplebrass break between the copper and galv. slows down the reactionenough that will out live the existing galv. pipe that is left.

As far as I'm concerned the jury is still out on DEUs. As I said earlier, Ihaven't seen where they are making much difference and I haven't seen whereit makes much difference whether it's an electric, gas, or oil fired WH.~C~

I'm having trouble getting homeowner's insurance (in California) because of the old galvanized plumbing and am told that a 'substantial' replumbing to copper will satisfy the insurance companies. Water heater is in basement so it will go pure copper; house is 1 story high and the galvanized vertical sections left will be about 4 to 5 feet long.And as I asked initially, 'how long does the nipple need to be?'

I found the following URL's helpful - though they don't directly address the question I posed initially.http://www.mtec.or.th/th/research/famd/corro%5Chowmetals.htmhttp://www.corrprev.org.au/Galvanic.htm

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Ask the other plumbers who visit here from time to time if a brass nipple doesa better job than a dielectric union to help control the effects ofelectrolysis

> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

>It is far wiser to spend the money and time checking the >sacrificial anode rod every couple of years and replacing >it when it is badly corroded.

The OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

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Well enough of that. I, probably like most of us, started using dielectricunions when they became code some time back. I really can't say I've seenany WH's longevity increased by using them. I, like Jeff, found wheninstalling DEUs on steel nipples, an accelerated corrosion took placeattacking the steel nipples. In one case it was galvanized nipples on my ownwater heater. It had been installed about 5 years when I disconnected it toredo the flooring under it. The galvanized nipples where totally corroded onthe inside and just about closed to the point of restriction with rust. Igenerally use dielectric nipples when using dielectric unions, but I was outof them when I installed my water heater. I have since seen this conditionin other WHs.Rheem Pro series WHs have dielectric nipples preinstalled. They also offeran extended warranty kit which consists of an extra anode rod attached to aพ" dielectric nipple which installs in the hot side tapping. But get this;Rheem gives you a brass, พ" x 1" bushing for WHs with 1" tapings.So, what's up with all of this? Is the key to always use dielectric nippleswith dielectric unions? Is it just as well to connect directly to the WHwhether it's copper, brass or steel? Does it all depend on water andelectrical conditions in a particular house and area?As far as I'm concerned the jury is still out on DEUs. As I said earlier, Ihaven't seen where they are making much difference and I haven't seen whereit makes much difference whether it's an electric, gas, or oil fired WH.~C~

I sliced the leaking nipple open. You can see it at:http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

I suppose it would work just as well for a galvanized to copper connections asthe material in galvanized or black you're trying to isolate the copper from isiron.Doug

A brass nipple will not break the electrical continuity of the path through whichthe galvanic current flows, and will do little at all to retard galvanic corrosionof the dissimilar metals.I think your experience, while I'm sure it's convinced you, was not a definitivetest, unless you set up two systems next to each other, identical in all respectssave for the addition of those brass nipples.Those who are still using dielectric unions thinking they are "protecting" electrichot water heaters should be aware that they are wasting their money, because theinsulating gap in the union is shorted out by the tank's electrical ground (percode) through it's power wiring, and the copper piping (if done to code) which isalso grounded. Those two grounds produce an electrical short right across theinsulating gap of the dielectric unions, rendering them useless for their intendedpurpose.It is far wiser to spend the money and time checking the sacrificial anode rodevery couple of years and replacing it when it is badly corroded.I learned this the hard way, because the last time I replaced my electric hot waterheater I went to the trouble of installing a pair of dielectric unions, standing on2-1/2" galvanized nipples screwed into the tank's cold and hot ports. In just oneyear one of the nipples started leaking right through its wall. I pulled thingsapart and found both unions and nipples pretty well clogged with big rust crystals,and badly corroded spots on the inside of the nipple walls.I replumbed everything with copper and copper unions. I think it's better to letthe copper run righ to the tank ports, so that the galvanic currents have a bettershot at working on the sacrificial anode.I sliced the leaking nipple open. You can see it at:http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

>It is far wiser to spend the money and time checking the >sacrificial anode rod every couple of years and replacing >it when it is badly corroded.

> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

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That's why I was barfing about dielectric unions helping only if there isn't a "sneak path" for electric current to flowaround the insulating gap in those unions.Jeff

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--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

I learned this the hard way, because the last time I replaced my electric hot waterheater I went to the trouble of installing a pair of dielectric unions, standing on2-1/2" galvanized nipples screwed into the tank's cold and hot ports. In just oneyear one of the nipples started leaking right through its wall. I pulled thingsapart and found both unions and nipples pretty well clogged with big rust crystals,and badly corroded spots on the inside of the nipple walls.I replumbed everything with copper and copper unions. I think it's better to letthe copper run righ to the tank ports, so that the galvanic currents have a bettershot at working on the sacrificial anode.I sliced the leaking nipple open. You can see it at:http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

I agree with Doug that when using galvanized nipples and die-electric unionsthe nipples will quickly fill up with rust. I have come to the conclusionthat for steel tank water heaters on copper pipe the best way is come outwith male adapters and forget about D.E.U.'s.The worst problems I've seen is when running a circulated domestic hot watersystem on galvanized pipe with a COPPER water heater (A.O. Smith Burkay).The hot water piping popped pin holes all over the system. ( 283 bed nursinghome) over a period of twenty years. I would definitely use die-electricswith a Burkay piped to galvanized.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

The worst problems I've seen is when running a circulated domestic hot watersystem on galvanized pipe with a COPPER water heater (A.O. Smith Burkay).The hot water piping popped pin holes all over the system. ( 283 bed nursinghome) over a period of twenty years. I would definitely use die-electricswith a Burkay piped to galvanized.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

> If I understand all of this correctly, the issue is not how well a> pipe conducts but how electrochemically reactive it is when placed in> contact with a pipe of different composition.

I'd like to add my experience to this. I've been a plumber for 30 years,changed many a water heater in my day. Remember when water heaters lasted20+ years? The old John Woods and Bradley WHs seemed to last the longest. Istill have a few customers with them, still going strong; never saw adielectric union on one of them. Do you think they would have lasted anylonger if they had? Isn't it a shame the crap they call WHs now hardly last5, 6, 7 years, with or without dielectric unions.Well enough of that. I, probably like most of us, started using dielectricunions when they became code some time back. I really can't say I've seenany WH's longevity increased by using them. I, like Jeff, found wheninstalling DEUs on steel nipples, an accelerated corrosion took placeattacking the steel nipples. In one case it was galvanized nipples on my ownwater heater. It had been installed about 5 years when I disconnected it toredo the flooring under it. The galvanized nipples where totally corroded onthe inside and just about closed to the point of restriction with rust. Igenerally use dielectric nipples when using dielectric unions, but I was outof them when I installed my water heater. I have since seen this conditionin other WHs.Rheem Pro series WHs have dielectric nipples preinstalled. They also offeran extended warranty kit which consists of an extra anode rod attached to aพ" dielectric nipple which installs in the hot side tapping. But get this;Rheem gives you a brass, พ" x 1" bushing for WHs with 1" tapings.So, what's up with all of this? Is the key to always use dielectric nippleswith dielectric unions? Is it just as well to connect directly to the WHwhether it's copper, brass or steel? Does it all depend on water andelectrical conditions in a particular house and area?As far as I'm concerned the jury is still out on DEUs. As I said earlier, Ihaven't seen where they are making much difference and I haven't seen whereit makes much difference whether it's an electric, gas, or oil fired WH.~C~

> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

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>I've heard that a brass nipple can be used to join copper to galvanized>pipe instead of a dielectric union. Is this true?

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

Since the EPA changed the acceptable pH range of potable water in 1991from 6.9-8.5 to 6.5-8.5, most 'city' water has been more acidic. A waterwith pH 6.0 is 10 times more acidic than a water of 7.0 (neutral) pH.That's not the only thing that will shorten heater and plumbing materiallife. Things like bacteria, DO, CO2, chlorides, sulfates and TDS contentplus chlorine etc. all have a negative impact on material life. Also,electrical grounding and grounds do too.Take a look here for more info on water caused corrosion:http://www.corrosion-doctors.org/NaturalWaters/Frames.htmGaryQuality Water Associates

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> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

Take a look here for more info on water caused corrosion:http://www.corrosion-doctors.org/NaturalWaters/Frames.htmGaryQuality Water Associates

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I think your experience, while I'm sure it's convinced you, was not a definitivetest, unless you set up two systems next to each other, identical in all respectssave for the addition of those brass nipples.Those who are still using dielectric unions thinking they are "protecting" electrichot water heaters should be aware that they are wasting their money, because theinsulating gap in the union is shorted out by the tank's electrical ground (percode) through it's power wiring, and the copper piping (if done to code) which isalso grounded. Those two grounds produce an electrical short right across theinsulating gap of the dielectric unions, rendering them useless for their intendedpurpose.It is far wiser to spend the money and time checking the sacrificial anode rodevery couple of years and replacing it when it is badly corroded.I learned this the hard way, because the last time I replaced my electric hot waterheater I went to the trouble of installing a pair of dielectric unions, standing on2-1/2" galvanized nipples screwed into the tank's cold and hot ports. In just oneyear one of the nipples started leaking right through its wall. I pulled thingsapart and found both unions and nipples pretty well clogged with big rust crystals,and badly corroded spots on the inside of the nipple walls.I replumbed everything with copper and copper unions. I think it's better to letthe copper run righ to the tank ports, so that the galvanic currents have a bettershot at working on the sacrificial anode.I sliced the leaking nipple open. You can see it at:http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

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If you stick the bottom ends of a zinc and a copper rod in a glass jar of saltwater, you won't get much corrosion ifthey're not touching each other, but connect the top ends with a piece of wire (even one a hundred feet long) and watch howmuch faster the zinc corrodes.Remember the old zinc/carbon flashlight batteries, and how they'd leak and ruin your flashlight if you discharged them toomuch? That happened because the zinc shell got eaten through by the galvanic corrosion which took place when you connectedthe carbon to the zinc through the flashlight bulb.That's why I was barfing about dielectric unions helping only if there isn't a "sneak path" for electric current to flowaround the insulating gap in those unions.Jeff

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

>It is far wiser to spend the money and time checking the >sacrificial anode rod every couple of years and replacing >it when it is badly corroded.

Hey guys, the one common thing to all water heaters regardless of thetype of plumbing and anode rod materials, or the manufacturers, is thewater quality. I've only seen it mentioned what, twice in the wholethread? All water is wet and most of it is clear but that's where thesimilarities between one location and another cease. Unseen differencesin water quality ranges all over the board and you'll find that dictateshow well the plumbing/appliance materials it contacts do in regards totheir service lives.Since the EPA changed the acceptable pH range of potable water in 1991from 6.9-8.5 to 6.5-8.5, most 'city' water has been more acidic. A waterwith pH 6.0 is 10 times more acidic than a water of 7.0 (neutral) pH.That's not the only thing that will shorten heater and plumbing materiallife. Things like bacteria, DO, CO2, chlorides, sulfates and TDS contentplus chlorine etc. all have a negative impact on material life. Also,electrical grounding and grounds do too.Take a look here for more info on water caused corrosion:http://www.corrosion-doctors.org/NaturalWaters/Frames.htmGaryQuality Water Associates

> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

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--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

>It is far wiser to spend the money and time checking the >sacrificial anode rod every couple of years and replacing >it when it is badly corroded.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

I tried my best not to offend you, but the "technical reasoning" I choked over wasyour statement that:"in my experience a brass nipple does a pretty good job of electrically isolating

Those who are still using dielectric unions thinking they are "protecting" electrichot water heaters should be aware that they are wasting their money, because theinsulating gap in the union is shorted out by the tank's electrical ground (percode) through it's power wiring, and the copper piping (if done to code) which isalso grounded. Those two grounds produce an electrical short right across theinsulating gap of the dielectric unions, rendering them useless for their intendedpurpose.It is far wiser to spend the money and time checking the sacrificial anode rodevery couple of years and replacing it when it is badly corroded.I learned this the hard way, because the last time I replaced my electric hot waterheater I went to the trouble of installing a pair of dielectric unions, standing on2-1/2" galvanized nipples screwed into the tank's cold and hot ports. In just oneyear one of the nipples started leaking right through its wall. I pulled thingsapart and found both unions and nipples pretty well clogged with big rust crystals,and badly corroded spots on the inside of the nipple walls.I replumbed everything with copper and copper unions. I think it's better to letthe copper run righ to the tank ports, so that the galvanic currents have a bettershot at working on the sacrificial anode.I sliced the leaking nipple open. You can see it at:http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

And, FWIW, I'd gone through two heaters in this house in twenty years prior tousing those dielectric unions when installing the third heater. There was NObuild-up or damage to the copper tubing or fittings at the tank in all that time.Go to the site below and you'll see that, since iron is higher in the galvanicseries than copper or brass, corrosion attacks the iron, not the copper. (Zinc iseven higher in the table than iron, that's why they use zinc anodes, which corrodeand "protect" the iron tank.) You'll also see that brass is right next to copper inthe series, so there shouldn't be much difference if it's used as you described.http://www.mcnallyinstitute.com/CDweb/g-html/g002.htmIf you can honestly state that all of the tanks you've changed which had brassnipples between them and copper piping had insignificant buildup or damage to thecopper tubing AND all the ones you've changed in the same town which didn't havebrass nipples had significant buildup or damage to the copper tubing, then I'llapologize to you a second time.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

6" Febco LF850 Double Check Valve Assembly, less gates. Known as the Master Series, the LF850 is an epoxy coated, ductile iron body with bronze check ...

I tried my best not to offend you, but the "technical reasoning" I choked over wasyour statement that:"in my experience a brass nipple does a pretty good job of electrically isolating

> Labratory test are all well and good to give an indication of anticipated> results but quite often fields results vary dramatically from lab results.

> Ask the other plumbers who visit here from time to time if a brass nipple does> a better job than a dielectric union to help control the effects of> electrolysis

Boiler waterfeeder

Hope this goes to the right place; I've been having a little trouble postingin news groups lately.I'd like to add my experience to this. I've been a plumber for 30 years,changed many a water heater in my day. Remember when water heaters lasted20+ years? The old John Woods and Bradley WHs seemed to last the longest. Istill have a few customers with them, still going strong; never saw adielectric union on one of them. Do you think they would have lasted anylonger if they had? Isn't it a shame the crap they call WHs now hardly last5, 6, 7 years, with or without dielectric unions.Well enough of that. I, probably like most of us, started using dielectricunions when they became code some time back. I really can't say I've seenany WH's longevity increased by using them. I, like Jeff, found wheninstalling DEUs on steel nipples, an accelerated corrosion took placeattacking the steel nipples. In one case it was galvanized nipples on my ownwater heater. It had been installed about 5 years when I disconnected it toredo the flooring under it. The galvanized nipples where totally corroded onthe inside and just about closed to the point of restriction with rust. Igenerally use dielectric nipples when using dielectric unions, but I was outof them when I installed my water heater. I have since seen this conditionin other WHs.Rheem Pro series WHs have dielectric nipples preinstalled. They also offeran extended warranty kit which consists of an extra anode rod attached to aพ" dielectric nipple which installs in the hot side tapping. But get this;Rheem gives you a brass, พ" x 1" bushing for WHs with 1" tapings.So, what's up with all of this? Is the key to always use dielectric nippleswith dielectric unions? Is it just as well to connect directly to the WHwhether it's copper, brass or steel? Does it all depend on water andelectrical conditions in a particular house and area?As far as I'm concerned the jury is still out on DEUs. As I said earlier, Ihaven't seen where they are making much difference and I haven't seen whereit makes much difference whether it's an electric, gas, or oil fired WH.~C~

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."

It is far wiser to spend the money and time checking the sacrificial anode rodevery couple of years and replacing it when it is badly corroded.I learned this the hard way, because the last time I replaced my electric hot waterheater I went to the trouble of installing a pair of dielectric unions, standing on2-1/2" galvanized nipples screwed into the tank's cold and hot ports. In just oneyear one of the nipples started leaking right through its wall. I pulled thingsapart and found both unions and nipples pretty well clogged with big rust crystals,and badly corroded spots on the inside of the nipple walls.I replumbed everything with copper and copper unions. I think it's better to letthe copper run righ to the tank ports, so that the galvanic currents have a bettershot at working on the sacrificial anode.I sliced the leaking nipple open. You can see it at:http://home.comcast.net/~jwisnia18/PIPERUST.jpgThe OP's appears to be at UCSF. It might be interesting for him to verify what I'vesaid above with a prof in the chemistry department who is a guro inelectrochemistry, I'm just a flatfooted electrical engineer, not a chemist.Just my .02.Jeff (Who sometimes misses the San Francisco he was born in back in 1936.)PLUMBGURU2 wrote:

If you can honestly state that all of the tanks you've changed which had brassnipples between them and copper piping had insignificant buildup or damage to thecopper tubing AND all the ones you've changed in the same town which didn't havebrass nipples had significant buildup or damage to the copper tubing, then I'llapologize to you a second time.

--Jeff Wisnia (W1BSV + Brass Rat '57 EE)"If you can smile when things are going wrong, you've thought of someone to blameit on."