Quick basic advice on a dripping gas 40-gal hot-water heater

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I don't believe it's accurate to say these tests were designed by the industry. The manufacturers of water heaters certainly gave there opinions and suggestions, but the actual test standards were arrived at by the EPA. And different manufacturers have different opinions of how the various water heaters should be tested. They were not even close to being all in agreement.
However, I do agree with most of what you posted. Tests have to assume some type of typical usage to come up with a way to do the tests. And just like with cars, your mileage may vary, especially if your usage is substantially different than the tests. And once the tests are set in place, manufacturers will start to tweak there designs to play the spec game. That's why I wouldn't go crazy trying to figure this out to the last decimal place.
When I needed a new water heater, I went with another 50 gal unit, which was what I already had. I did look at the energy efficieny ratings and concluded that for my usage an average unit would be fine. I went down to HD, bought it and installed it in one day. It has a eff rating of .56, and cost me I think about $300 7 years ago. I wasn't gonna lose sleep worrying over whether a .58 or .61 was gonna make enough difference to be worth it.
I did get a 10 year warranty, which came in handy about 2 years ago. The thermocouple went and State, who was the manufacturer, had a new one here in 2 days for free.
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No, the tests are done per EPA rules and specs by an independent testing lab.
Now, on the other hand, those tests are performed under a certain set of criteria based on an estimate of how the water heater would actually be used. I would say the difference in how someone will actually uses it in practice as compared to how it was tested, could easily outweigh small differences in the recorded test data under the controlled conditions. I would bet that a heater rated at an eff of . 61 vs one at .58 could easily be a wash or even upside down in actual use. Same thing for the first hour rating.
In other words, over analyzing this whole thing is likely a waste of time. Even the above payback analysis is flawed, because it ignores the time value of money. Laying out $135 today and getting it back over the next 6 years doesn't account for the fact that the money could be earning a return. Or if you put the heater on a credit card and pay interest, even for a short time, and the perceived savings are gone. Take any of that into account and the difference between these heaters shrinks.
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On Wed, 13 Feb 2008 06:16:37 -0800 (PST), snipped-for-privacy@optonline.net wrote:

I agree. Intertek Testing Services is supposedly independent. If anyone has information otherwise, please post.

Very good point.
Here are the original calculations I posted for inspection: a. Additional cost of more efficient model = $882 - $747 = $135 b. Annual savings of more efficient model = $313 - $288 = $25 per year c. Payback period = $135 / $25 * 365 / 30 = 65 months (5.4 years) e. Overall savings = (13 years - 5.4 years) * $25/year = $190
How would we change these to take into account the time value of money? As always, I'll hazard my math to see if it stands up to scrutiny.
Using the compound interest calculator here ... http://www.moneychimp.com/calculator/compound_interest_calculator.htm that $135 at 5% compounded monthly over the 5.4 years payback period actually costs $176.75 at the 65-month point.
You're right. That's a big difference! (I don't use credit cards so I won't factor in the additional, but huge, credit-card costs if paid on installment!)
Conversly, the annual savings over that same 65-month period is also increased, from $25/year to $26.28 per year using the same 5% interest rate compounded monthly.
This more accurate payback-period calculation then becomes $177 / $26 * 365 / 30 = 83 months (6.9 years).
The overall savings now shrinks a whopping 16% from $190 when not taking into account the time value of money, to (13 years - 6.9 years) * $26/year = $159
Thanks for testing the math. Please let me know what you think of the new, more realistic calculations which take into account the time value of money.
Donna PS Can someone in the field write a calculator to do all this math for us?
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((snip))

Vehicle mileage estimates, or for that matter any estimates, are based on a load of assumptions. Your actual experience will vary according to how closely your situation matches the assumptions. By the way, vehicle manufacturers follow a standard test procedure specified by federal law, and the EPA confirms 10%-15% of the results by conducting its own tests.
I agree that the rated fuel consumption for motor vehicles is off - I haven't averaged that low for at least 15 years. For instance, my car is rated 20/29 for city/highway - last week I averaged 33.2 mpg in about 440 miles of mixed driving according to the car's odometer and the reading on the pump when I gassed up on Friday evening. According the average mileage display on the dashboard of the car, I got 34.1 mpg, and I suppose the difference could be due to the attendant (no self service gas in NJ) filling the tank right up to the gas cap and/or inaccuracies in the pump or odometer, or even simply to the fact that I fill up the tank at the end of the day (when the car and the gas is at its warmest) but do about half my driving in the morning (when the gas is the coolest). Which means simply that a full measured gallon on a Friday afternoon is probably less than a gallon on Monday morning simply due to the expansion and contraction that go with changes in temperature.
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The expansion and contraction based on temperature for a volume as small as a tank of fuel in a car are so tiny that you'd never be able to measure them with anything around the house, and certainly not the odometer in your car. The fuel temperature varies over a range of perhaps 60F max, usually much less.
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Just to be devil's advocate, I used to have a Rabbit GTI that I got with a bad gas cap; the first time I parked it in the sun with a full tank of gas, the fuel started pouring out around the gas cap and down the quarter panel :(
nate
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the energy guide labels on appliances arent really to determine exact operating costs/
their real value is in comparing efficenies in a general way.
obviously a home with 8 kids will use a lot more hot water than a single guy living alone.
with so many variables, incoming water temp, desired water temp, amount of water used, cost of gas, etc etc,.
everything is a estimate
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Well, maybe I'm calculating wrong. There's an approximately 3% difference between what I calculate as my miles per gallon for last week and what the car calculated. The coefficient of expansion of gasoline is 0.069% per Fahrenheit degree. Coincidentally, over a 30 degree temperature difference, that's between a 2% and a 3% change in volume. For 15 gallons of gas, that comes somewhere between 3 and 4 ounces of gas.
The meter on the pump reads out several digits to the right of the decimal point - it appears that this level of accuracy is available at the gas station. The odometer reads out only to the tenth of a mile, which means that I don't have the accuracy at my end to calculate this by hand. I don't know what the internal accuracy is when the car computes average miles per gallon - I presume the fuel pump knows pretty precisely how much gas it's pumped, and the odometer measures distance covered by counting revolutions of something (one of the wheels?), and it seems reasonable that the internal accuracy of the car's computation is more than adequate to notice a difference of this magnitude.
I guess the other consideration is that the car is likely computing average mpg using the gas burned (or at least, pumped to the engine) while any by hand calculation is basing it on gas bought, and any difference the fill level will throw the result off. Last week, the attendant took great pains to fill the tank right up to the brim (he was evidently trying to get the total to come out to a whole dollar amount), something that usually doesn't happen. So I have no problem believing that I bought slightly more gas than I burned.
Whichever figure is right and whatever the explanation, it still seems to me that the mileage estimates published by the EPA are too low, and it's seemed that way ever since I started paying attention (way too many years ago).
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Lou wrote:

EPA figure is based on sea level wht IDEAL driving condition, weather, road, wind, temp., etc.
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EPA numbers are bogus the worst were on vehicles like PRIUS.
tests always favor the manufacturer..........
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According to the EPA's fuel economy guide for 2008, the Prius is rated at 48/45 for city/highway. The 2008 model year isn't very far advanced and there's only 23 2008 models listed in the shared fuel economy estimates, but those drivers claim actual mileage of 35 to 56 mpg, with an average of 43.5, I'd say the estimates aren't that bad. The best driver claims an average of 56.2 mpg for 38% stop and go and 62% highway driving - that car is driven in Arizona. The worst driver claims a mere 35.1 for a car driven in California - no percentages for city/highway are given.
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Considering that the EPA's National Vehicle and Fuel Emissions Laboratory is located in Ann Arbor, Michigan, and that Ann Arbor is about 840 feet above sea level, and that the EPA conducts its own tests at this facility, I think your claim that the mileage figures are based on sea level conditions is suspect.
Considering that starting in 2008 supplementary tests are conducted to estimate the effects of high speed (up to 80 mph), use of air conditioning, and cold temperatures (down to 20 degrees F), the claim that current figures represent ideal conditions also seem somewhat out of sync with the facts.
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Lou wrote: <snip>

20 degrees F cold? It is high time that automotive design and testing accommodate the northern climates where cars last about as long as a snowflake on a hot radiator. Test in International Falls in February on a track laden with salt and urea at minus 20 degrees F.
Michael
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On Thu, 14 Feb 2008 20:53:12 -0500, "Lou"

something else - not interested enough to look into it, but I'm sure they lab test versus "real world." Think you said you had an Impala, and the 3.1 engine coupled with the GM lockup trans is an efficient combo. I consistently get 30-31 mpg highway with mine ('97 Lumina) over a long stretch of varied terrain. Measured by actual gas pumped into the tank over many thousands of miles. My '88 Celebrity with the 2.8 did about 28 mpg, but always had a heavier passenger load.
--Vic
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The news 2008 figures take real life into consideration and are much closer to reality. Previous figures were ideal lab conditions.
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wrote in message

It all points down to the fact that average Joe citizen can't tell the difference unless he can find out exactly how they take all these measurements (The method used and exactly what figures) that each company used and how (If they did) manipulated those figures to get the result as they publish. The main thing that the Government is interested in is a standard across the relevant industry so everyone can make a comparison. Justy.
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The tests are performed by independent labs to the EPA test procedures and standards. It's not up to the maufacturers to decide how to test, nor can they manipulate the results for the cars. Same thing for the water heaters.
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-

no the manufactuers knowing the test procedures tweak the product to look as good as possible
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Yes, some of that can certainly be going on. But trying to change the design of the product slightly to come out better in the standard EPA test is a lot different than claiming the tests themselves are not uniform because the manufacturer gets to decide the test method, how the test is done, etc, and then manipulates the results they publish.
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On Feb 15, 10:33 am, snipped-for-privacy@optonline.net wrote:

well everyone knew the old tests werent valid yet it took many years to get them changed
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