OT: Replacing a plastic water heater drain valve
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  1. #1
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    Default OT: Replacing a plastic water heater drain valve

    As this forum dispenses advice on everything from rectal surgery to trimming shrubs I thought I would give this a try. I purchased a new 50 gallon water heater and the factory drain valve is now made from a white plastic. I need to remove it to install fittings for a thermal siphon system but am a bit nervous. I reefed on it with a wrench and it refused to move. I can give it hell and bust it off, then remove the remains, but would like to get it out in one piece.

    Has anyone successfully removed a plastic drain valve, intact?

    I guess the right answer is pull on it until it either comes loose or busts...!

    Stuart

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    Quote Originally Posted by atomarc View Post
    As this forum dispenses advice on everything from rectal surgery to trimming shrubs Stuart
    LMAO, more tea sprayed over the screen and keyboard

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    Ours was 39 years old when it started leaking, the plastic drain assembly may be a press fit (followed by threads that engage) into a plastic fitting that is screwed into a 3/4th inch pipe fitting. it had a rather small internal cross section, the water essentially had to flow through hardly a 1/4" hole equivalent. as a valve it may not be of much use, given that if you step on it accidentally you might break it off!


    so if you can't see a hexagonal shape behind the valve to get a wrench on it, you may just have to unthread it as far as it will go and then pull it out, then you should find whatever it is that threads into the tank.

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    I've thought about swapping the plastic valves with brass, but haven't. Surely it's a threaded piece that screws into a bung on the tank. Worst case scenario, it breaks and you melt it out with a torch.

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    This valve does have a large flat for a wrench and the replacement valves shown by the mfg have traditional pipe threads. I guess the sensible approach would be to try to unscrew it with a large crescent wrench..it'll come or it'll break off, either way it's out and I accomplished what I set out to do.

    The tank is probably glass lined so hitting it with a torch might not be a wise move..dunno.

    Stuart

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    Quote Originally Posted by Limy Sami View Post
    LMAO, more tea sprayed over the screen and keyboard
    Well why? He was RIGHT!

    And polite, too. We've seen a lot worse than either of those!


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    Quote Originally Posted by atomarc View Post
    This valve does have a large flat for a wrench and the replacement valves shown by the mfg have traditional pipe threads. I guess the sensible approach would be to try to unscrew it with a large crescent wrench..it'll come or it'll break off, either way it's out and I accomplished what I set out to do.

    The tank is probably glass lined so hitting it with a torch might not be a wise move..dunno.

    Stuart
    Exact same need here where I use the required periodic flush-down of our serious lime deposits thru a garden hose to clean the driveway or water plants or .. wotever.

    Plastic valve's alleged stem gland is offering to leak if not carefully fiddled with each shut-off. I have plenty of better valves, from higher-grade plastic to Bronze & stainless.

    No dice so far. Large well-fitted wrench just starts to distort the plastic. Channelocks get an adaptable grip, but clearly threaten to break it. Not the first one I have had this same issue with.

    In my case 25-year old WH, I'll ignore it 'til change-out, fit the NEW WH with a better valve before I ever fill it.

    If you NEED to get this one JF done, make sure you have a pipe tap that fits so you can clean up the rusty threads after you bust it out so the new sealant protects well.

    The glass lining never reaches into those threads - they rely only on sealant, and it is seldom used on plastic valves at the factory. THEY don't have to deal with OLD WH.

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    First thing I do with a new water heater is pull that POS plastic valve and install a brass ball valve. I've never seen one that wasn't 3/4 NPT. The plastic valves have always come out without trouble.

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    Quote Originally Posted by Gordon Heaton View Post
    First thing I do with a new water heater is pull that POS plastic valve and install a brass ball valve. I've never seen one that wasn't 3/4 NPT. The plastic valves have always come out without trouble.
    Yer right.

    But given I try to keep lime build down, and recently put new elements in at the 20-odd year mark, what with 30+ years between new installs, we tend to FORGET what a PITA the new plastic valve will become and put-off that new valve from "zero day" to ten or fifteen years down the line.

    Give 'em their due - they usually last longer than they have any visible RIGHT to do.

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    Quote Originally Posted by atomarc View Post
    The tank is probably glass lined so hitting it with a torch might not be a wise move..dunno.

    Stuart
    You would only have to heat the broken plastic piece to soften so you can remove it. Shouldn't take much heat.

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    I've taken a few dozen out. Usually with hot water in them. Just have the other valve taped and ready to go. In your case, I'd have the brass nipple, tee, valve and dielectric union already stuck together. Those plastic jobs usually come out with a little force. Never broken one. However, a crescent wrench may slip around the pretend hex. Got a pipe wrench?

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    Plastic has a higher coefficient of expansion. Perhaps chilling the drain valve may help.


    I've never had much difficulty removing them.

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    Quote Originally Posted by Monarchist View Post
    . . . I try to keep lime build down . . .
    That's why I change it right away. It is much easier to get a good flush with a lever-type ball valve than with those twisty things. The hole the OEM valve opens up is easily blocked by mineral chunks. When you 'exercise' the lever it breaks up the globs and lets 'em out!

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    Quote Originally Posted by Gordon Heaton View Post
    That's why I change it right away. It is much easier to get a good flush with a lever-type ball valve than with those twisty things. The hole the OEM valve opens up is easily blocked by mineral chunks. When you 'exercise' the lever it breaks up the globs and lets 'em out!
    We all know that. I probably just have a higher 'procrastination index' than average!

    Last go, I drained the tank below the lower heater-element level, pulled the elements, poured in a whole gallon of cheap household 'white vinegar', came back the next day to get that silly valve to flow, flush it all out, install the new elements.

    Kinda dumb, really. For the value of the f**k-with time involved I cudda dropped in a whole new 90 gallon WH.

    But 'kinda dumb' is pretty common when we THINK we are saving money and pushing-back the nuisance-day when we have to haul a new one home, alter the plumbing 'coz Sod's Law sez they won't be a perfect match, then also haul the grubby, rust and lime leaking old tank to the landfill/recycling center, ain't it?


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    Took one out of a new heater. Used a pipe wrench, thought it
    break for sure because it was so tight, but it came loose.

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    I don't know how far it stubs out but can you just cut it off, take a jib hacksaw and cut into it (without hitting the threads! ) from the center making a couple of sections. Then break them loose with a chisel or punch from the outside of the exposed protrusion. I've done it before with black iron but started in with a sawzall then switched to a hacksaw when close to the threads. I'd think with plastic it would be easy. Nothin' says it has to come out in one piece.

    Disclaimer: Results may vary

    JR

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    Quote Originally Posted by b sco View Post
    Took one out of a new heater. Used a pipe wrench, thought it
    break for sure because it was so tight, but it came loose.
    New heater?

    Try that on a 10 to 25 year old one. Let us know whether it breaks.

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    We purchased a 50 gallon water heater for the family cottage last year. Family members go there at all times of the year. We don't heat the place year round so every time someone goes there during the winter months they have to turn on the heat, start the pump, and fill the water heater.

    As mentioned the original drain valve is painfully slow. When it was installed the plumber removed the original plastic valve and replaced it with a 1/2" pipe nipple and a ball valve. I was there when he was removing the original plastic valve. It was in so tight he had to put an extension on a 12" pipe wrench. It came out in one piece, but left some kind of sealant residue in the threads. Before he could get the new 1/2" galvanized pipe to thread in properly he had to run a tap through the threads to clean out the gunk.

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    Quote Originally Posted by projectnut View Post
    Before he could get the new 1/2" galvanized pipe to thread in properly he had to run a tap through the threads to clean out the gunk.
    "Galvanized", eh?

    Didn't take me long to figure out that if you had a corrosion challenge, galvanized was nowhere near good enough to deal with it.

    If you did NOT have a corrosion challenge? Galvanized could create one.

    Useful for quick unpainted temporary handrails is all. No place in any sort of "plumbing" around me.

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    atomarc said it was a new water heater.


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