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Galvanized pipe is main feed, corroded at copper junction.

KoanKoan Member Posts: 436
Hi all
I'm in Baltimore city. Moving into a townhouse built in 1928. the inside plumbing is nearly 100% copper (or so it appears) Nice work, good solder joints, parallel runs, Type L, 1" main runs. The feed to to the house is a large Galvanized pipe, the OD measures 1.683 inches so I assume it is SCD 40 1&1/4 pipe.
Naturally, where the galvanized meets the copper 1" main in the house, it is corroded badly. Pressure gauge on the inlet side reads 120psi. PRV (Watts N35B 1") outlet side reads 120 psi also when static, but goes down to 40 psi when water is running.
I know this is a problem waiting to happen and needs attention. I ask for sharing of wisdom.

1) I am more inclined to replace the PRV rather than rebuild - considering a Watts 25AUB-Z3 1", but looking for advice here. I am nervous about undoing the lower union nut with the corrosion from electrogalvanization about a foot below this joint. If I replace, is that an ok PRV or should I consider something else.

2) Most importantly I know the main feed should be replaced. It goes under a small stone patio and a piece of sidewalk but appears to be a completely straight run of only about 35 feet. What would be the correct size and material to replace the main?

3) can a digging Mole (horizontal trencher) go from the house out to water valve? there seems to be room in the basement to do this, and it would avoid ripping up 10 feet of the patio. on the other side the water meter is on the opposite side of the sidewalk.

Please help me to make sure this is done correctly - thank you!


Comments

  • SWEISWEI Member Posts: 7,356
    How big is the house? How far is the run to the meter? Do you really need a one inch main?

    Trenchless replacement could be an option, but without seeing the layout it would be hard to make any specific recommendation.
  • ZmanZman Member Posts: 6,028
    Picture would really help.
    If you in fact have corrosion on the inside that is showing on the outside, the pipe is totally gone.
    Would it be an option to cut out the bad section of pipe and re-thread? Galvy pipe usually fails first at the unprotected ends, especially with dissimilar metals present.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • KoanKoan Member Posts: 436
    @SWEI thanks for the response! RE:the run:
    appears to be a completely straight run of only about 35 feet.
    RE: your comment do I really need a 1" Main?
    The current main is 1.25 ID galvanized, the house is 3 stories about 2900 sq ft. I don't know if I need a one inch main, but the bathrooms used to have (and one still does ) a sloan flush valve rather than a toilet tank. The biggest trunks in the basement are 1" copper. I assume a 1" main should be sufficiently large. 3 full baths and two half baths. what material though? Copper?
  • KoanKoan Member Posts: 436
    @Zman - you make a good point, actually two. I know the pipe is shot at the junction between galvanized and copper. If I hit it with a hammer it would let go. It may be possible to unscrew the 1.25 x 6 inch nipple going to the copper fitting, put in a new nipple, then a dielectric union. My fear is that if that does not work and the whole feed is bolloxed and I have no water! eventually the galvanized will occlude and fail. It would be a calculated risk. I'll try to attach a pic tonight. Thanks!
  • SWEISWEI Member Posts: 7,356
    Photos would definitely help. The flush valve is going to drive the need for full flow, quite possibly even the 1-1/4". Replacing the flush valve toilet with a tank type could quite likely allow even a 3/4" supply line depending on the line pressure and type and quantity of fixtures. A 3/4" copper pipe may be able to slide through the old 1-1/4" even without a bursting head.

    Replace the section of nipple using brass or stainless and you can skip the dielectric. They're nothing but trouble IME.
    delta T
  • KoanKoan Member Posts: 436
    @SWEI Thanks! good points! Any comment on the Watts Pressure reducing valve?
  • SWEISWEI Member Posts: 7,356
    Watts makes a good PRV. I wouldn't hesitate to install one.

    Back to the dielectric for a moment: A dielectric union only provides about 1/16" of physical separation between the two metals. A section of nonconductive or neutral metal pipe will greatly increase the electrical path length (through the water.) Not sure if PEX is approved in your jurisdiction, but we use it for underground mains all the time. The reduced ID needs to be taken into account when sizing, but (barring sharp rocks or wayward trenchers) it should outlast you. PVC is not code approved inside (or approaching) the building envelope, but a threaded Sch.80 nipple will get the job done for very little coin.
  • KoanKoan Member Posts: 436
    @SWEI Thanks! So please allow me to summarize so I know I understand?
    1) Watts PRV is good
    2) Dielectric union is not enough separation to really prevent electrolysis, use Brass or stainless . Could use plastic Scd 80 PVC fittings (as a temporary fix to avoid a blowout)
    3) See if PEX is code approved for feed.
    4) be careful reducing feed diameter - do come calculations.
    Yes?
    Zman
  • SWEISWEI Member Posts: 7,356
    That's how I would approach it.
    KoanZman
  • KoanKoan Member Posts: 436
    @SWEI - thanks you kind sir!
  • KoanKoan Member Posts: 436
    looking at options now. Is 1& 1/4" or 1" (assume properly sized) type K soft coil ok for an underground main. I figured better that 3 sections of hard 10' type K because there would be no joints??
    thoughts anyone?
  • ZmanZman Member Posts: 6,028
    Soft type K copper is what is generally used for underground in my area.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HillyHilly Member Posts: 412
    If you used hard drawn copper lengths and it is approved for underground there the methods of joining may be limited. Brazing and Flaring are the only code-approved method of joining copper 'under-building' in Can, not to be confused with underground outside the foundation walls. Also I'm not certain but there is an AWWA service lateral standard for Pex also. I'm not sure whether all pex piping automatically carries that standard or if you need to purchase ones specifically rated for that purpose.
  • KoanKoan Member Posts: 436
    bought 60' of 1 1/4" K copper coil for under $300. Just a matter now of getting to it
  • ratioratio Member Posts: 2,566
    We had our old, leaky galvanized water line replaced, the plumber chained the K copper to the old line & used his backhoe to pull the old out & the new in. Worked like a champ--only a little hole where he had to tie in at the valve. Something to think about.
    Koan
  • KoanKoan Member Posts: 436
    @ratio SO I assume they connected the copper to the galvanized inside and pulled it through from the outside? Good idea... but I am thinking I still need a hole at the house to seal it and one at the meter to pull it. Thanks for the idea!
  • ratioratio Member Posts: 2,566
    Pretty much that. (It isn't sealed to much at the house, just on the inside, but I don't ship any water.) Mine was one of the first to go in the neighborhood, there's about two or three a year now, but it was one of the best. Nearly everyone else gets their lawn dug up.
  • delta Tdelta T Member Posts: 814
    Re: Watts PRV.

    The 25AUB is a good PRV, I have put in plenty of them and they do work well and last.

    That being said....for the past few years I have been using Cashe Acme EB-25C valves and have been very impressed. They are quiet, adjust without the need for tools, have a dial that shows the pressure you are setting, have a wider secondary pressure range than the 25AUB, and repair is SOOOOOO easy. Literally shut off the water, loosen one nut, remove cartridge, put new cartridge in, tighten nut, turn water back on. The brass body is nothing more than a chunk of brass. All parts and seals get replaced with a new cartridge. Price is pretty competitive as well.
  • KoanKoan Member Posts: 436
    Thanks! @delta T
  • hot_rodhot_rod Member Posts: 13,882
    edited October 2016
    delta T said:

    Re: Watts PRV.

    The 25AUB is a good PRV, I have put in plenty of them and they do work well and last.

    That being said....for the past few years I have been using Cashe Acme EB-25C valves and have been very impressed. They are quiet, adjust without the need for tools, have a dial that shows the pressure you are setting, have a wider secondary pressure range than the 25AUB, and repair is SOOOOOO easy. Literally shut off the water, loosen one nut, remove cartridge, put new cartridge in, tighten nut, turn water back on. The brass body is nothing more than a chunk of brass. All parts and seals get replaced with a new cartridge. Price is pretty competitive as well.

    Let me send one of these to you for an opinion, it has some unique features.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • DoRightDoRight Member Posts: 7
    1. I would replace main run, not to be bother with b.s. "Dielectric union", its garbage in most of use test cases, just waist of money.
    2. There is some method drill horizontally, specially whee "old pipe" in place and can be use as "guide".
    I saw this video where guy drill 30 foot manually horizontal run, seems to with not to much headache



    But if you prefer "give it a shut as is" , then you should buy "electrical ground rod- about 8 foot", push it to the ground near this joint, and have two clams from both side of connection going to "electrical ground rod". This should stop galvanization processes you have, and this joint should last pretty long.
    Just make sure you have very good connection and put some grease prevent rust around those are.
    Similar method use , when copper wire jumped across in/out of water heaters.
  • DoRightDoRight Member Posts: 7
    p.s. and its always good idea, place pressure reducer as close as possible to the "load" - your appliances(this way "high pressure" will go over longer distance, while your low pressure distance is reduced in same). If you will be able move about lets say 20 foot closer, overall water supply should increased noticeable in some cases can solve you that missing "just a little more pressure" demand on appliance side.
  • KoanKoan Member Posts: 436
    I will end up replacing the entire main, but first as a stop gap I will use a brass street elbow to replace the rotted union between the galvanized and copper pipe.

    The main feed is 1-1/4" and the trunk line in the house are 1" so for now water pressure is not at all an issue.

    I am not a pro, so this next statement could easily be wrong, but it seems better to have the PRV near the feed (as long as no boost in pressure is needed) so that there is less stress on all the inside plumbing - valves and joints of all the feeds.
  • hot_rodhot_rod Member Posts: 13,882
    Koan said:

    I will end up replacing the entire main, but first as a stop gap I will use a brass street elbow to replace the rotted union between the galvanized and copper pipe.

    The main feed is 1-1/4" and the trunk line in the house are 1" so for now water pressure is not at all an issue.

    I am not a pro, so this next statement could easily be wrong, but it seems better to have the PRV near the feed (as long as no boost in pressure is needed) so that there is less stress on all the inside plumbing - valves and joints of all the feeds.

    Correct, the PRV should be installed before any fixtures or valves. Often it is installed by the main water shutoff where it enters the building.

    They do require service of cleaning from time to time, being accessible is a plus.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • KoanKoan Member Posts: 436
    @hot rod Thank you!
    BTW I never responded to your kind offer for a PRV sample. I already have the Watts 1-1/4 25AUB with a union on both sides. I am not against trying a new device, but since I have the Watt PRV I would be more inclined to install that now. I'd be happy to try your PRV down the road if (or when) a replacement is needed.
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