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Thread: Proper water heater installation?

  1. #1
    DIY Member MushCreek's Avatar
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    Default Proper water heater installation?

    I'm working the rest of my way through my plumbing (new house), and I'm hooking up an electric water heater. My question concerns the T&P valve outlet and drain pan. The WH is in an unfinished (for now) basement. Since I'd like to eventually finish the basement, I'm putting the WH in a drain pan on a stand. This gives me enough height to pitch a drain pipe outside. The question concerns the outlet for the T&P valve. One book says to drain it into the pan; the other book says NEVER drain it into the pan! If I knew which of my three plumbing books to believe, I'd burn the other two, as they are filled with conflicting advice. I'd prefer to drain the T&P into the pan as opposed to dumping it on the floor- is this done? I could make a separate drain on the same drain pipe, if its against code to drain into the pan. Also, what is a good way to terminate the drain outside? A trap could freeze in the winter, but a plain pipe might become a highway for small critters. Thanks for any insight!

  2. #2
    DIY Senior Member Smooky's Avatar
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    The drains from a hot water heater donít get used unless something goes wrong. Around here most everyone drains the T&P drain into the pan, if there is a pan. You could let the pan drain indirect into a drain with a trap inside the basement. The T&P drain could also go to it if it is indirect. Making it indirect and putting it in the basement would allow you to have access to the drain. You could put vegetable oil in the trap so it does not dry up so fast.


    Take a look at the image in this link.
    http://www.diychatroom.com/f7/run-dr...-heater-77933/
    Last edited by Smooky; 07-21-2013 at 04:40 PM.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    THat valve often just weeps, but if there's a major problem, it could come out of there with a lot of force. Under normal circumstances, it should only let out water when you test it. IF you want a bit more protection, look at www.wagsvalve.com. To get the warranty, it has to be installed by a trained pro, though.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
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    Normally a water heater relief line is piped outside the building six inches above the ground.
    That's how I do my installs.

    It can also daylight 6" above the floor if you can't do that.
    If there is a floor drain nearby, even better.

    If I can't gravity drain the relief, I install a 125 PSI pressure relief on the cold side in a location where it "can" be drained.
    In theory, the 150 PSI on the water heater would never need to be used. The city of Bellevue expected all of their water heaters to be plumbed that way for years. I didn't like it, so I would install the 125 PSI on the cold for the inspector, and the 150 PSI on the water heater for me.

    Draining to the pan is better than nothing.
    Last edited by Terry; 07-23-2013 at 09:09 AM.

  5. #5
    DIY Member MushCreek's Avatar
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    A floor drain is not a practical option. The WH is about 16' from the outside wall. This is a walk-out basement, so the wall the WH is on is several feet under ground, but the back wall is at grade. I was going to run a drain line along the wall, drill through the concrete wall, and terminate it outside. If I pipe the T&P all the way out, the air gap would be outside, right? This doesn't leave me anything for the pan, though. I guess I'll go with dumping the T&P into the pan, and then pipe the pan outside, and see if the inspector is OK with it. Thanks for the idea of putting the trap inside; hadn't thought of that. I'm used to FL where things don't freeze! Thanks for the input- my inspections so far have been very brief, and I'm more concerned about doing things right, as I don't think the inspectors will catch anything but a really gross error.

  6. #6
    Moderator & Master Plumber hj's Avatar
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    The T&P valve drain is a "pressure" flow. The drain pan has a "gravity" flow. IF the T&P valve discharges, the pan drain will NEVER keep up with the T&P valve's discharge, and it will overflow the drain pan in a matter of seconds. Extend the drain to the outside of the building separately.
    Licensed residential and commercial plumber

  7. #7
    DIY Member MushCreek's Avatar
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    So I would have to have TWO outside drain lines? I have to go through 8" of concrete. I'm trying to figure out if there's a way to accommodate both the T&P and the drain pan with a single penetration through the wall. Can I have a separate gravity flow from the pan join the T&P line somewhere downstream? I wouldn't think so, since that T&P flow would be under considerable pressure, so it could back up to the gravity drain. Still, it IS 'code' to simply let the T&P dump on the floor, since the basement is, as of now, unfinished.

    My house is ICF, with 8" of steel-reinforced walls. I asked the contractor who was assisting me for a list of penetrations so I could create them well before pouring concrete. He left quite a few off of the list, so I'm doing a fair amount of drilling already. Should have thought it through and made my own list....

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Rent a concrete boring drill and it'll chop through the wall easily.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  9. #9
    Moderator & Master Plumber hj's Avatar
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    It IS code to simply dump it on the floor, IF doing so would not cause damage to the area or its contents, which is seldom the case.
    Licensed residential and commercial plumber

  10. #10
    DIY Member MushCreek's Avatar
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    I have a rotary hammer and bit. Not fun, but it does go through the wall pretty quickly. I'll make two holes, and run a gravity drain from the pan, and pipe a drain from the T&P. I'm thinking I'll put a trap inside for the gravity drain, but not bother with the T&P pipe. There's nowhere for critters to go in that one.

  11. #11
    Moderator & Master Plumber hj's Avatar
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    A trap will be useless unless you pour some water into the pan every week to keep the seal intact.
    Licensed residential and commercial plumber

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