WH lifetimes

Discussion in 'Water Heater Forum, Tanks' started by Thatguy, Aug 22, 2009.

  1. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    Anyone have data on how long their gas water heater lasted?
    How 'bout for elec.?
  2. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    Some heater last for years and years, others only a few. I think it is due to mineral content in the water as much as anything. Don't know if there is a difference between lifespan of gas and electric. I would never use electric if gas was available.
  3. gusherb94

    gusherb94 Member

    Messages:
    124
    Location:
    chicago/nw IN
    We still have the original Ruud 50 gallon high recovery water heater in our house, the water heater is 19 years old.
    My grandma had a Ruud 40 gallon standard recovery water heater installed in 1990 and it's death was induced by a flood that devastated her neighborhood, it was still going strong. That was 18 years old.
    The water heater in our 3 unit apartment building is 13 years old, still going well. 50 gallon State.
    My aunt's 30 gallon A.O Smith water heater lasted 16 years before the tank rusted thru at the inlet nipple and it was just replaced less than a month ago with a G.E.
    A person I know had their water heater's bottom drop out on them when it was approximately 15 years old (this was back in the 90s), they got a new one about 15 years ago and I hear that it's starting to leak.
    All the water heater's I listed are on city water from lake Michigan, it's pretty common around here to have water heater's last 14-17 years and not rare to have them going over 20 years.

    :EDIT: all of the above water heater's are gas models.
    Last edited: Aug 22, 2009
  4. here you go...

    read all this horsh-sh//
    and tell me what you think
    http://www.weilhammerplumbing.com/generalinfo/

    our area has some pretty aggressive water..

    I am finding that when a waterheater goes out before the
    warranty has expired, usually their is a water softener installed
    in the home......

    so does the sodium in the water eat the anode rod away quicker
    or is the problem the fact that the ground for the home is usually installed
    on the soft side of the plumbing system???.

    http://www.weilhammerplumbing.com/generalinfo/
    Last edited: Aug 23, 2009
  5. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    equipment replacement strategy

    Thanks, that's what I'm looking for.

    Ok, so for gas heaters, lifetimes are

    13
    14
    15
    15
    16
    17
    18
    19
    20

    so 89% last longer than 13 yrs and 89% last less than 20, and if your heater lasts 16 yrs you have a 50-50 chance of going another 2.5 yrs.

    Here's an HVAC example
    1
    7
    7
    10
    10
    12
    12
    13
    15
    15
    15
    18
    18
    20
    20
    20
    20
    20
    20
    25
    30
    30
    35
    50
    56

    so if your HVAC has lasted 25 years you have a 50-50 chance of getting to 35 years.

    The more datapoints, the more accurate the likelihoods.:D
  6. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I don't think you have enough data points to be statistically significant with those numbers. But no matter what the number is...let's say you are at the 15 year point on a water heater, and you come up with some number that says you have 1 chance in 3 of lasting 5 more. Or whatever.

    What does that mean....how do you do a cost benefit of the added years about the potential damage caused by a leaker? How do you measure the hassel factor of having the WH croak at the most inopportune time?

    There a certaily plenty of gas WH today which do not outlive the 6 year warranty. But how many of those were due to faulty install??
  7. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    1 30 is a statistically large sample, assuming they are representative samples. If you have less than 30 your uncertainty increases and somewhere I have a table that gives me these numbers.
    2 The HO decides his risk/benefit tradeoff. In a way, lifetime is determined by parts availability and the willingness of the HO to sink more money into this machine. There are also equip. replacement strategies based on purely economic considerations. In one sense, buying a drip pan is paying a one-time premium on an "insurance policy".
    3 See 2.
    4 These are lifetimes due to any and all reasons. It's all averaged out in these numbers.
    Last edited: Aug 23, 2009
  8. I don't care how long a water heater lasted,



    The efficiency of that heater went down dramatically the longer it sat in use.


    And since people think what they don't know won't hurt them, a water heater that came with a V-8 running on 4 cylinders with a terrible energy rating is not important to the fact that it doesn't leak or not.


    Every 6 years is when water heaters should be replaced to even remotely follow those energy guide stickers.

    If you think a water heater that's operating 20 years old only costs you what the sticker says on the side of it...
  9. Terry

    Terry Administrator Staff Member

    Messages:
    15,125
    Location:
    Bothell, Washington
    I've had two forced air furnaces go bad, the heat exchangers cracked and were letting carbon monoxide into the home.
    One was 28 years old and the second one was 15 years old.

    The 28 YO one may have gone bad before this, but this is when I bought the home, and it was replaced before closing.
    I feel sorry for the people that lived with the bad furnace for how many years?
  10. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    So efficiency drops to 50% by 6 years? You have a link?
    This should be easily measured by seeing how much gas or kwh it takes to raise the water temp. 1 BTU per pound of water per degree F and 1 Therm of energy from approx. 100 cubic feet of natural gas or 29 kwh of elec heat.

    Because, now the replacement time would also depend on how much you spend per therm of NG or elec., in addition to how much a new heater costs.

    Sounds like the strategy behind Cash For Clunkers. What's good for society may not be good for each individual in that society.
    Last edited: Aug 23, 2009
  11. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    There are probably a hundred thousand plumbers in the US. Home depot alone sells around 10,000 water heaters a week. A sample of 30 from 6 old geezers on the forum here.....????
  12. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    Representative or not, it's all I got. . .!:eek:
    "Because there is very rarely enough time or money to gather information from everyone or everything in a population, the goal becomes finding a representative sample (or subset) of that population."
    from
    http://en.wikipedia.org/wiki/Sampling_(statistics)
  13. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    OK.....we've had a good Sunday set-to over this issue!. Now....maybe I missed it.....what was the point of the question? A lot of water heaters "live" way beyond what woudl be a reasonable expectation, and a lot die young. Many are replaced before D-day, "just because". Where does all this leave us?
  14. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    With help deciding on a repair/replace decision. . .:confused:

    I see from Lowe's website
    http://www.lowes.com/lowes/lkn?action=categorySelect&Ne=5000&category=Water Heaters&N=0 1000092
    that most gas WHs cost between $400 and $600. For HVAC equipment this method may be more sought-after, since there is more money riding on the decision.

    BTW, same website, the elec. ones are probably close to 100% efficient (and don't lose efficiency with time?) so at $200 to $400 they seem to clearly be the better buy, assuming one therm of NG costs the same as one therm of elec.
    Last edited: Aug 23, 2009


  15. Do I have a link? NO, I am THE LINK.


    I've installed hundreds of water heaters...how bout you?

    I've seen them installed and not touched since the day they was installed, they call when they break, nothing inbetween.

    From day one, sediment builds in the bottom of them...even if you drain them once a year, that sediment starts to hard scale inside the tank and will not come out, ever.

    Furthermore, calcium deposits/mineral buildup become a common thing inside the water heater.


    Do you not comprehend that an energy guide rating only is dictated off a brand new unit?


    Realistically speaking, if you did install water heaters on a regular basis, you would get the famous statements after an old one has been replaced, "We can't believe how much hot water we have now, and how much faster it recovers."


    That's the efficiency as stated on the yellow tag, years from now you can erase those numbers because it grows progressively larger.

    You are not making accurate comparables to anything, and as jimbo stated precisely, you're not statistically significant.

    Your numbers are fictitious and do not represent anything because there are far too many variables that determine the longevity of a water heater.

    Believing a water heater lasting 20 years thinking it is efficient is ignorance. Go to a junk yard and cut an old one open, then tell me where the capacity went along with the ability to transfer heat through solid calcium deposits at the bottom of the tank.


    Posting resource links from l0wes? Are you kidding me?
  16. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    They're just numbers. Why are you so upset?
    Last edited: Aug 23, 2009

  17. I'm never upset. I just cannot believe that you are not considering what the inside of a water heater turns into over years, how it lessens in capacity, how it makes it so hard to transfer heat whether by element or burner.


    If you only knew how often I come into homes with thermostats cranked up well beyond the 120 degree setting and they're telling me they keep running out of hot water...and I've checked to make sure it doesn't imply a failing dip tube scenario...it proves the tank has lost its true worth as a working unit.


    But people weigh the fact that it isn't leaking as a primary move to switch out. Rarely do people change out a heater before it leaks. I do them, and if you saw the condition of some, you'll know why they are pleased with the recovery of the new ones.

    I've got some great knowledge of water heaters and a slew of situations like other plumbers have on these sites, but what you're gauging is something that doesn't guarantee efficiency of a unit. Look at tankless heaters for example: you have to keep those compartments delimed/descaled or those numbers are just junk science for those who compare therms or kilowatt usages.

    One thing I will not do in plumbing is build false hope. Even though I instruct my customers to drain their water heater once a year, the reality is that water heater loses the cost per annual year first number rather quickly, depending on water quality.


    If they made a water heater that defied water quality issues, you could definitely produce a list like you have going, knowing the efficiency isn't compromised.
  18. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    In what world does that happen?

    Although it varies by time of year, baseline usage, etc. we have numbers something like $1.16 per therm NG. Elect. will run 16 to 29 cents per kwh. You do the math.
  19. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    Not very compelling, unfortunately.

    I've used some pretty old gas water heaters and their gas use wasn't that much different than what I've seen in new units.

    I don't doubt that efficiency declines as fouling occurs (I expect it) but I've yet to experience anywhere near the magnitude you suggest we all should see in such a short time. In fact, I can correlate my summer natural gas use in various homes with the shower heads/bath habits, clothes and dish washers, as well as with differing supply water temps for different latitudes, but not by age of the water heater.

    Six years is a ridiculously short life expectancy. In fact that would argue against doing anything other than a really cheap install of a short warranty unit. Is that what you really want? ;)

    Since I've seen numbers by plumbers on this site staring around $800 and up for a gas water heater install it seems highly unlikely that replacing a 6 year old gas fired unit would make any economic sense. It would certainly start to make electric water heating more attractive than it would otherwise be.

    So as Thatguy asked, have you got anything hard to back your claim? If the efficiency decline is even a fraction of what you state then I would expect to see some studies showing why water heater replacement should be on a short schedule. Efficiency loss is mentioned regarding old refrigerators for example. However, I've also recovered quite a bit of refrigeration efficiency (measured with a Kill-a-watt meter over a week) via thorough condenser coil cleaning...getting back close to nameplate on a 14 year old unit.

    As for Thatguy's suggestion that electric could make more economic sense than gas, the problem is that the thermal efficiency of the powerplant is in the mid-30's per DOE. A 62% efficient gas water heater will kill a 92% efficient electric water heater once that is factored in. This is reflected in the pricing of natural gas versus electricity. Makes sense as electricity is a higher energy form, converting it back into heat is an unnecessary conversion sequence. Skip the intermediate steps and go thermal direct.

    I'll offer you this with regards to your observation of lost efficiency: in the last few months of a badly-fouled fired water heater's life I would expect it to enter a death spiral on increasing fuel use and rapid increase in corrosion as wall temps rise. (That's not unlike what I've seen in doing process heat exchanger troubleshooting in fouling services.) A plumber is going to see that effect because they get the call when the unit has become untenable.
  20. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    99 44/100 % of all the replacements I do are because the unit starts to leak...some times during an install I am asked how long the new unit will last and I tell them (with a smile) that crystal ball readings are an additional $75.00...then they laugh...

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