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Thread: Electric water heater installation - certain code requirements

  1. #1
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    Electric water heater installation - certain code requirements

    I'm curious about why plumbing codes (in locations different than mine) have some of the following requirements.

    1. Accordion type flexible water line connections are not allowed. (As Steve Lavimoniere says in https://www.youtube.com/watch?v=UoMzdqO5AZU ) I don't know if this also applies to the pressure relief drain.

    2. A vacuum breaker must be installed on the cold water line. (He says it keeps the tank from collapsing should the fire department start using a lot of water from the main iine - only a concern in big cities?)

    3. A top-mounted factory installed "short stem" pressure relief valve must be replaced by a "long stem" pressure relief valve.

    From other videos:

    4. A service disconnect box is required. Romex cannot be used to connect the disconnect box to the heater. (In my location, the pros use a cable that resembles an appliance cord for a dryer or stove.)

  2. #2
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    What is your source for the specifications of these codes?

    The code may be the pressure relief valve needs to reach in to the top 6" of the water heater. Is that what you mean by "long stem" versus "short stem"?

    Vacuum breakers are usually required on irrigation lines.

    Accordion lines may be subject to failure.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  3. #3
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    In California accordian gas lines are required. Not sure about water lines but they sell a lot of them at the Borgs in town.
    The service disconnect viable from the tool itself is required in a shop. Romex has to be supported within 12" of the box so a service whip seems logical.
    California requires water heater to be strapped down so they do not fall over and break off gas, electric and water lines in a quake. That should be required in NM?
    Bil lD

  4. #4
    Quote Originally Posted by Stephen Tashiro View Post
    I'm curious about why plumbing codes (in locations different than mine) have some of the following requirements.

    1. Accordion type flexible water line connections are not allowed. (As Steve Lavimoniere says in https://www.youtube.com/watch?v=UoMzdqO5AZU ) I don't know if this also applies to the pressure relief drain.

    2. A vacuum breaker must be installed on the cold water line. (He says it keeps the tank from collapsing should the fire department start using a lot of water from the main iine - only a concern in big cities?)

    3. A top-mounted factory installed "short stem" pressure relief valve must be replaced by a "long stem" pressure relief valve.

    From other videos:

    4. A service disconnect box is required. Romex cannot be used to connect the disconnect box to the heater. (In my location, the pros use a cable that resembles an appliance cord for a dryer or stove.)
    Codes are just someone's opinion. You will find some of them that don't make any sense. It's also why every town has different codes. Lots of different opinions.

  5. #5
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    It's been a long time since I remember seeing a water heater with a top-mounted pressure relief valve. They are easily converted to a "long stem" by soldering in copper pipe.

  6. #6
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    Thinking about the "accordian" type flex hoses, I'm not even sure the ones they're talking about are even still on the market. The first ones they came out with had built-in compression washers in the ends. If you tightened them too tight they would leak, but not right away, and were very critical to have just the right torque.

    I've had nothing but good luck with the newer stainless steel braid covered hoses with ends that look like stainless female garden hose ends. Those have some sort of high temperature washers (guessing), that look like regular garden hose washers, that are very forgiving with tightening pressure.

  7. #7
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    The vacuum breaker applies to more than just a city water line issue. Technically depending on the location of your water heater and a myriad of other factors in your plumbing system, just draining the lines could pull enough vacuum to cause a tank issue but it would be EXTREMELY rare. But thats what the code is for. Its to cover the extreme rare instance. No different than vacuum breaker requirements on outside silcocks for the issues of cross contamination. You toss your garden hose in your kiddie pool and your 1 year old is splashing around in their peeing and crapping in their diaper and the watersupply (city or otherwise) has an issue and you wind up in a back flow/siphon situation and you contaminate your potable water supply lines with urine and fecal kiddie pool water. Same issue with drain loops on dishwashers, air gaps on washing machine drains. When I apprenticed in the 80's you were not allowed to use a hooked washing machine drain that sat in the drain line. There was a metal clamp that held an air gap between the washing machine hose and the drain line so there was zero chance of waste water getting into the washer and somehow getting into the potable water supply. How that could ever happen I do not know.

    Filling your dishwasher with a filthy load of sink water is easy if you didnt install a high loop on the drain line though most dishwashers now incorporate that loop into the side of the machine from the factory.

    6" Temp and pressure relief valves not being allowed an must be swapped for 8" has been common in many places for 40 years because the thought is the edge of the tank can be cool enough to not cause the relief to trip. If you want to learn about the nightmare of an exploding water heater start doing some research. The latent energy in a water heater with super heated water and no relief valve or one that was plugged because it is weeping is mind blowing. Imagine 40 gallons of water (9240cu" or 5.34cu') instantly expanding 1728 times its volume in an instant when that super heated water flashed to steam when the tank bursts. That 5.34 cu' of water instantly becomes 9240cu' of steam. Its a bomb. In trade school incidents were commonly referenced where entre wings of schools and commercial buildings were blown off the face of the earth by a water heater with no, or a plugged, relief.

    Relief valve drain lines being rigidly extended to within 6" of the floor is so that if anyone is working on or servicing the heater, or anyone is close to the heater, when the relief trips they cant be under it.

    It goes on and on, pressure balanced/anti scald shower valves, and so on.

    The code can seem a little kooky at times but at its core it is simply a minimum standard and based on some crazy stuff happening that no one ever thought possible.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  8. #8
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    Great post Mark!

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    Imagine 40 gallons of water (9240cu" or 5.34cu') instantly expanding 1728 times its volume in an instant when that super heated water flashed to steam when the tank bursts. That 5.34 cu' of water instantly becomes 9240cu' of steam. Its a bomb. In trade school incidents were commonly referenced where entre wings of schools and commercial buildings were blown off the face of the earth by a water heater with no, or a plugged, relief.
    That must be the inspiration for the insurance commercial with the flying water heater.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  10. #10
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    Quote Originally Posted by Jim Koepke View Post
    That must be the inspiration for the insurance commercial with the flying water heater.

    jtk
    Itd be nice if they flew through the roof like a rocket lol. But it's more like an improvised explosive device that goes in all directions coupled with superheated scalding steam.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  11. #11
    There was a Mythbusters episode years ago that explored the myth of the exploding water heater. Adam and Jamie built a small minimum code-compliant house and placed the water heater inside, disabled the safety mechanisms on the water heater and then let the pressure build. When it burst, the water shot through the roof of the house like a rocket, flying several hundred feet in the air, and the house collapsed into a pile. It was one of my favorite viewing moments ever on the show. And I immediately went down and checked my water heater to verify the pressure relief valve and drain were in good working order.

  12. #12
    A couple dozen years ago in one of the St Paul suburbs a water heater exploded. I remember it from the news story. It shot through the roof and knocked the house of its foundation. They reference the incident in the Mythbusters episode.

    https://www.upi.com/Archives/1993/06...4054738993600/

  13. #13
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    According to the IRC an electrical disconnect is required. This is usually a simple switch mounted nearby. From what I understand it is required so the power can be disconnected easily for any maintenance and repairs.

    I have not heard the corrugated lines are prohibited so it may be a local or statewide issue. While the home improvement centers sell them I would opt for the woven stainless steel hoses, similar to ones used for washers, for a few extra dollars. I once helped a friendís dad rebuild his place after a corrugated copper line developed a pin hole leak. There was so much water that his walnut floors popped up and the side yard flooded.

  14. #14
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    Quote Originally Posted by Derek Meyer View Post
    When it burst, the water shot through the roof of the house like a rocket, flying several hundred feet in the air, and the house collapsed into a pile.
    Id imagine most light residential tanks would fail at top or bottom where the pressed ends are welded on for the rocket effect. If I remember correctly the school incident was in TX and was a large commercial stone lined heater. Either way, its a bad day.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  15. #15
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    I replaced a water heater using the stainless flex hoses with garden hose type connections on the hot water side galvanized steel pipe connection. I had a terrible time getting it to seal. The cold water side was fed by a copper pipe so I used a shark bite (on one end) style stainless flex hose. Worked much better. By the way, they aren't really that flexible, they need to be almost the exact length.
    NOW you tell me...

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