Working with black gas pipe and water heater.

Discussion in 'Water Heater Forum, Tanks' started by sschoe2, Oct 11, 2018.

  1. sschoe2

    sschoe2 Member

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    Oct 11, 2018
    Location:
    Chicago
    Hi all

    I just bought a home and the water heater is going to need to be replaced soon. It is 11 years old and it was not installed with dielectric unions causing heavy corrosion on the water fittings and some on the top of the heater tank. I am pretty good with plumbing. I am also a chemist and work a lot with gas lines though I am used to Swagelok and other compression fittings. I live in stupid Illinois which code requires all rigid connections so I can't use the yellow flex line.

    How do you work with black pipe that is threaded on both ends. I assume you can't loosen it on one fitting without tightening on the other so you need to find a union with a compression fitting and take it apart from there then once it is free from the union you can unscrew the whole set from the water heater? Is that right? Also I naturally don't have the cutting and threading tools so can I go to the hardware store and ask them to cut and thread the pipe to length if I end up having to alter the gas pipe length? Any tips on lifting the big old heater alone?
     
  2. sschoe2

    sschoe2 Member

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  4. Dana

    Dana In the trades

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    It's not possible to assemble it with all threaded connections without a union somewhere on the path, so find it. I may involve disassembling quite a bit of gas plumbing though, depending on just how stingy they were in the original installation.

    Even though you are experienced, many states don't allow un-bonded non-licensed uncertified people to work on gas lines, so a completed DIY on this may put you at some liability if something ever goes wrong with it. Check your local regulations on that.

    An old water heater full of lime deposits can be quite hefty. It's sometimes necessary to cut them up with an abrasive saw to get it out, or drag it out with a block & tackle.

    The corrosion on the top of the tank looks more like backdrafting/condensation damage than galvanic corrosion. The union in the picture looks like it IS a dielectric union, with a plastic sleeve between the sweat copper and the outer compression ring that extends around to the mating surface.

    [​IMG]
     
  5. sschoe2

    sschoe2 Member

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    I just looked it up and agree. It has a quick elbow turn there. Perhaps I should buy a shorter heater when it fails so I can put a vertical section before the elbow.
     
  6. sschoe2

    sschoe2 Member

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    So it is probably more an HVAC/duct issue than plumbing the question is does the corrosion due to backdraft compromise the heater or is that corrosion on the exterior of the tank that shouldn't compromise the the lifespan too much if I have the backdrafting corrected? 11 years isn't too old I had a heater fail on the family home I sold earlier this year replaced at ~25 years of age.
     
  7. phog

    phog Active Member

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    Location:
    Rochester NY
    I don't know about the life of the heater being affected, but I doubt the draft issue would be solved by adding inches of vertical rise via a shorter water heater. It's more likely that you've got issues with the rest of the vent stack. There are a couple common issues to look for.

    First, was this water heater orphaned -- ie. did it used to share a larger vent stack with another appliance that is now gone? (typically a natural draft furnace/boiler that got replaced by a high efficiency direct-vent unit). If so then your vent is almost definitely oversized for just the water heater.

    Second, if this vent goes into a masonry chimney, is the flue lined with an appropriately sized liner? If not this can make flue gas spillage likely at the water heater.

    It's hard to tell from your picture how long the vertical section of vent is, but if it's just a short jog of a foot or two then it's pretty unlikely to be a problem.
     
  8. sschoe2

    sschoe2 Member

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    According to the inspection report if anything the water heater is over vented.
    upload_2018-10-11_12-13-44.png
     
    Last edited: Oct 11, 2018
  9. sschoe2

    sschoe2 Member

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    [​IMG]
    Here is a picture of the venting
     
  10. phog

    phog Active Member

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    Rochester NY
    The vent does need to be properly sized -- oversized is bad. The vent flue relies on a sufficient amount of heat in the stack to cause an upward draft. Your water heater's burner is too small to keep the stack properly heated, and so the upward draft is poor. It can even back-draft, typically during windy conditions and more so in the winter than the summer.

    Back when there was a furnace sharing the vent, there was plenty of heat from 2 appliances to keep the draft strong. Not so, anymore. This is the "orphaned" water heater scenario mentioned above and is likely the cause of the flue gas spillage that is making the top of your water heater corrode.

    In addition to making acidic condensation on the top of your water heater (which is causing the rust), the back draft is also spilling carbon monoxide into your living area. I don't mean to alarm you, the amounts are typically small and your carbon monoxide alarm would alert you to any dangerous situation. (you do have one right? if not you should buy one ASAP)! But this is something that should be addressed.

    To fix this problem correctly, you need to do one of two things.

    Option #1 is to get the vent sized reduced down all the way up through the roof, either by having a correctly sized liner installed (if this is a masonry chimney) or ripping out the old Type-B Gas Vent stack and installing new, smaller one.

    Option #2 is to install a direct-vent water heater (that goes out the side wall), and cap off this vent stack.
     
  11. sschoe2

    sschoe2 Member

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    Indeed I went over the report and the water heater is now orphaned looks like the HE furnace install was a couple years ago. Not sure what the best option is. sounds like liner would run ~$2-4k, direct vent water heater ~$2k, might as well consider tankless.
     
  12. Reach4

    Reach4 Well-Known Member

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    IL
    You are saying that for shock value? I suggest you read through the tankless forum (https://terrylove.com/forums/index.php?forums/tankless-water-heater-forum.17/), and see if that doesn't inspire you.
     
  13. phog

    phog Active Member

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    Don't rush into a decision, take your time. Make sure you have working carbon monoxide detectors in the house at all times just in case, but this is a somewhat common problem with natural draft water heaters and it doesn't typically cause an immediate health hazard except in severe cases.

    Since your water heater was installed 11 years ago, it falls under the old pre-2015 energy efficiency regulations. In 2015 they enacted new federal standards and as a result there is a huge reduction in the availability of natural draft gas water heaters, especially in the 50-75 gallon size range. When you go to buy your next water heater, you will find that the market changed and you may not be able to buy a direct replacement for what you have now. The older natural draft technology can't meet the new efficiency standards. Definitely something to think about if you're considering installing a new vent/ chimney liner -- you might be forced to go to direct-vent anyway next time you purchase a new water heater, and abandon your new vent stack.

    And, your water heater is getting up there in age. I understand you witnessed a 25yr lifespan on a different unit, but 10-15 years is more typical. So this isn't a crazy time to think about replacing it. You will also probably notice some improvement in performance (faster recovery time & lower energy consumption) even if you would have been able to squeak some more years out of this unit. As tanks age, they scale up on the inside, and perform worse and worse, and cost more and more to operate. That thought may take a little of the sting out of shelling out money for a new one.

    As far as tankless goes, they have their own issues. They do have a lower cost of operation in many cases, but the savings can get swallowed up by high repair costs when they need service calls. Also there can be comfort issues -- look up "cold water sandwich" (this can be addressed with a hot water recirculation loop). Some people love tankless and others hate them. An eternal debate.

    Good luck.
     
  14. Dana

    Dana In the trades

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    An 11 year old orphaned water heater is already overdue for replacement. It should have been replaced when the furnace was removed from the flue.

    Is the "... Furnace..." that got replaced with a high-efficiency version actually a boiler? If yes, an indirect fired water heater is a better solution all the way around.

    Does this basement need a dehumidifier to keep it dry enough to avoid the "musty basement" smell? If yes, a heat pump water heater might be the "right" option. A heat pump water heater takes humidity from the basement and delivers the heat of vaporization recovered into the water inside the tank, usually for comparable or lower annual operating costs than a gas-burner (tankless or tank), sometimes as expensive to install as a tankless.

    Tankless solutions usually only make sense if there is a crying need to conserve on space. That doesn't seem to be a problem based on your pictures. Tankless heaters also usually require upgrading the gas plumbing in the house, with a 1.25" dedicated gas line (no branches or tees to other appliances) hooking in as close to the meter/regulator as possible. It sometimes even requires upgrading the gas meter.

    Water heater basic questions for narrowing in on a solution:

    *How big is the biggest tub you have to fill?

    *How many full bathrooms?

    *How many occupants?

    *Primarily showerers, or tub bathers?
     
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Retired Systems engineer for defense industry.
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    New England
    FWIW, same volume new WH today are generally taller (at least in gas versions) as a requirement of the vapor ignition safety features in all new ones (they have a different air intake for the burner). That can make your existing flue issue even worse.
     
  16. sschoe2

    sschoe2 Member

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    I was just throwing the tankless out there. I don't know to much about it other than I keep seeing it harped on every home improvement show like its the best thing ever and tank users are anachronistic cheapskates or something. Yea it looks like it still has issues and needs to be descaled once a year with a pump and vinnegar.

    I am just concerned that winter is coming and the backdrafting could be a major issue. Sounds like if the CO isn't a major issue just wait for it to fail and replace next time with a direct vent.

    The furnace is a natural gas forced air. House is a small split level 1400ft2 with right now just me and 2 dogs and I don't use too much hot water just shower in morning, dishwasher, laundry, and cooking. I haven't even moved in yet I close on the 26th.
     
    Last edited: Oct 11, 2018
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Tankless systems do work, they have limitations, if those limitations fit with your lifestyle, you can be very happy with one. One area where they can lead to discontent is wintertime use with very cold incoming water. Think waving your hand through a candle flame. Move it slow, and you'll burn...move it fast and you probably won't notice. Now, the burner in one is a lot bigger than a candle, but the concept is the same...heating a low flow is one thing, but another when you're, say, trying to fill a tub before what's in there cools off because you have to dribble the water to get it hot! Been there, done that. During a cold snap, my water is literally barely above freezing (measured at 33-degrees). Your results may differ!
     
  18. Dana

    Dana In the trades

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    That sounds like it would have been a slam-dunk for a right-sized (for the heating load) hydro-air handler running off a condensing gas water heater with a 57-100,000 BTU/hr burner, but alas, that ship has sailed, for now. The design heat load is almost surely under 30,000 BTU/hr, and probably under 25K. (More often than not the furnace installed would be 2-3x that big, as if we were expecting cold snaps to hit -75F or colder.)

    For a low volume hot water user a plain old electric tank isn't insane. They are much cheaper to install than other solutions, and very low standby loss compared to a gas-burner. The EF ratings are assuming 63 gallons/day use- you're probably using less than half that. The as-used EF of a gas fired tank with just one shower per day + laundry /dishes for one person + 2 dogs will be MUCH lower than advertised, whereas the hit with an electric tank is less, and starting from a much higher number. Even though the input energy is much more expensive than gas, far less is wasted in standby.
     
  19. sschoe2

    sschoe2 Member

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    Oct 11, 2018
    Location:
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    Thanks for all the advice. I made an appointment with a chimney sweeper to install a 4" liner to correct the issue. It is only ~$6-700. Is there anything I can do to treat the corroded areas of the tank? I see no reason to replace it until it shows signs of being structurally compromised from the inside or stops functioning. Like I said my last tank lasted well over 20 years.
     
  20. Reach4

    Reach4 Well-Known Member

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    Location:
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    I like Por-15 primer, but it has been a while since I used it. Others prefer some other treatments.
     
  21. phog

    phog Active Member

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    Location:
    Rochester NY
    I wouldn't worry about it, the rust you are seeing is on the outside casing. Underneath that casing is a layer of insulation before you reach the surface of the actual water tank. So what you see there is cosmetic and not even on the water tank. The water connection fittings do have a little surface rust but that is no problem at all. You could hit them with a wire brush if you like things to look nice & shiny, but functionally it won't matter one bit.
     
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