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Thread: Draining a water heater

  1. #1
    DIY Junior Member DanGles11's Avatar
    Join Date
    Apr 2011

    Default Draining a water heater

    First of all, is it a good idea to drain a gallon or two from a Rheem Fury EverKleen gas water heater every two months or so? What does self-cleaning really mean? If I should be doing this, is it really necessary to shut off the gas to the pilot light and also turn off the incoming water supply line? Should I open the pressure relief valve also? What will happen if I don't take these steps? Why can't I just hook up a garden hose and open up the drain valve? Also, will having a Kinetico water softener shorten the life of the anodes? How much longer should I expect this water heater to last if it was installed in November, 2003 (taking the softener into consideration)?

  2. #2
    In the trades Dana's Avatar
    Join Date
    Jan 2009


    If it's been in service for 8 years it's time to swap the anode no matter what (it's 8 years old, after all- I usually swap 'em at 6 years even without the water softener.) It's condition may give you a hint as to how much water softener is hurting (or not- it's old). A DIY anode swap is less than $50, often less than $35. Once the anode is truly toast, broken off with just a stub hanging, tanks can go downhill as fast as Bode Miller. With a water softener system swapping anodes every 4-5 years might be necessary- it just depends. If the old one is still intact when you pull it, put date tag on the new one with both the installed date and an "replace by" date. If it's bare wire, shredded, falling apart, it's probably time to replace the beast before it leaks.

    Efficiency typically falls off over time though- in high fuel-cost areas (or with propane versions) it's cost effective to swap in a new one at 15 years even if it's well maintained. The center-flue heat exchangers inevitably corrode a bit on the fire-side, and lime up on the water-side leading to a lower average combustion efficiency. They start out life at ~80% steady-state efficiency, but it'll be 75% or less after more than a decade of service.

    The draining schedule is a bit ambitious and unnecessary- annually is usually "good 'nuff".

    How much longer it will last is always a WAG, but if the burner burns clean & isn't rusty-crusty and the anodes are swapped on a schedule they can easily go a coupla decades. If it's never maintained 10-12 years would be typical, but even some of those can go 20 years depending on volume of use and the water quality. Others can die within 6 years.

  3. #3
    General Engineering Contractor ballvalve's Avatar
    Join Date
    Dec 2009
    northfork, california


    A real water heater clean out for me is removing the drain valve and working it with a hose on a wet vac and a bit of water entering the supply line. Heres a 20$ fix, get the .91 diameter


  4. #4
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    Depending on how much you plan to flush, you may want to shut the gas off to let things cool. The water temp also plays a part in whether it's good to turn it off. If you are trying to flush it, you need water coming in, or some air, but then you'll only have gravity verses the water pressure, helping to push things out. Also keep in mine, some hoses aren't designed for hot water, and that can be problematic.

    If you replace the drain valve on a new WH with a full port ball valve, when you open it, you can stick a rod in there to help dislodge built-up crud. An old, plastic valve is likely to break off once it's been there awhile which can be a pain to clean out so you can install a new one. Plus, the threads may no longer be in good shape thus the recommendation to only do this on a new tank. Once crud sits there for awhile, it can get hard as a rock, and the only way to flush it out is to break it up first. that can create problems in itself, as you may damage the lining.

    If you haven't regularly tested the T&P valve, opening it can cause it to stick and leak. But, if it is stuck, it should be replaced anyway.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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