40 gal just not enough: Replacing water heater for 2400 sq home. Family of 2 adults + 2 children

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now THAT's funny. I don't care who you are. LMMFAO!!
s

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The only bullship is your knowledge, at my previous location I installed a $500 Bosch ng tankless, my bill went from 20 to no more than 10$ in summer, that includes gas dryer and stove, my payback is 4 years, where I am now is Ng Tank and last summers gas bill is back to no less than 22 with gas stove and dyer. Tank Ng are only near 60% efficent even with an 82$ efficent burner.
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BUT, can you get 140 - 160 degree water out of it?
I thought not. It doesn't matter if the junk mf's are FREE to run if you can't get what you need out of them.
s
The only bullship is your knowledge, at my previous location I installed a $500 Bosch ng tankless, my bill went from 20 to no more than 10$ in summer, that includes gas dryer and stove, my payback is 4 years, where I am now is Ng Tank and last summers gas bill is back to no less than 22 with gas stove and dyer. Tank Ng are only near 60% efficent even with an 82$ efficent burner.
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S. Barker wrote:

Out of curiosity what residential applications need those high water temperatures?
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dishwasher.
s

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Most dishwashers use the dryer element to further heat up the incoming water anyway. Dishwasher actually use much less water than most people realize.
However making the hot water hotter does mean you use less water from the heated line side in showers and sinks. It will make the difference between occasionally running out of hot water to rarely running out. I set my heater higher than the recommended "mark" on the temp dial specifically to get more shower time out of one tank full of hot water. We have pressure balancing shower valves so there isn't the danger of full hot water in the shower if someone flushes a toilet.
When we had our tank replaced a couple of years ago I had to specifically decline a safety device that would add cold water to the hot water leaving the tank if it detected it was higher than scalding temp. Apparently it is now code for new construction around here. In my mind I can't quite figure out if cooling "very" hot water to "fairly" hot water in the hot water line rather than at the shower fixture would reduce amount of running time for showers from one full tank of hot water. I'm thinking it would act the same as lowering the tank temperature so it would reduce the available run time.
Has anyone installed a hot water recirculator? The theory is that you keep the water in the hot water line hot so that you do not require any run time to get your shower or sink up to temperature.
Jeff

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the recurircuate lines saves water but wastes energy unless you turn it on specifically before using a fixture.......
the tempering valves prevent scalds, but keeping a tank hotter increases standby losses, and leads to shorter lank life from the thermal shock of very hot water and very cold water mixing.
there are no free lunches, gain a little here lose a little there.........
i prefer a larger tank, with higher BTU, and a lower temperature so no one can get scalded.........
your mileage may vary......
tankless owners see more wasted water since the tankless must detect flow and turn on burners before hot water arrives
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Thats bull shit in relavance to consumption, mine triggers in 1-2 seconds with maybe 1/2 gallon detection. How about tankless can last 30 years and cut your gas bill in half, Or tankless can have a remote theremostat in your shower so you dont waste money by heating water hotter than you need, which is 102 for me. Or as you say" Tanks heat your home" great idea when AC is running, Or the truth that tanks are really near 60% efficent. Look at a Takagi condensing TK1 its maybe 96% on propane with the SAME energy factor as its efficency rating. Now can you answer why tankless Energy Factor ratings are about the same as the efficency of the burner, because Tanks waste freakin energy up the chimney.
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No, it would act the same as mixing down the "very" hot water at the shower like you do now. It doesn't matter where you do the mixing--by raising the tank temperature you are still increased the amount of heat stored in the tank.
Wayne
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The Bosch units can be dialed up to 140 degrees. I realize that you get more water at a given temperature when you start with hotter water and mix in cold, but what do you need 160 degree water for? Considering that most of the time you'll mix it down to 120 degrees and the anti-scald showers won't let you go anywhere near 160, what's the point of heating water just to cool it down? If your system is undersized for the amount of hot water you need, cranking up the water temperature is a backwards way of adjusting it.
R
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a. if you crank them up that high, you'll get no useable flow to speak of b. i'd never have an antiscald shower valve c. the hotter the water is to begin with, the longer it'll last mixed down.
steve
wrote:

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Hi everyone.
I'd like to try and elevate the tankless vs. tank discussion a little bit. Let me just say however, kudos for actually bringing a citation into the conversation (WP article). Unfortunately the cited article is severely flawed. It attempts to generalize from anecdotal evidence, and neglects to mention a key benefit of tankless systems: they have an expected life time of OVER 20 YEARS (citation below).
The US department of energy discusses the pros and cons of the system, and I hope we can all agree that they are a reasonably reliable and unbiased source.
Check out: http://www.eere.energy.gov/consumer/your_home/water_heating/index.cfm/ mytopic820
I recommend reading the whole page. It's brief and highly informative. QUOTED from the DOE website:
-Most tankless water heaters have a life expectancy of more than 20      years. They also have easily replaceable parts that extend their life by many more years. In contrast, storage water heaters last 10–15 years.
-[tankless water heaters] don't produce the standby energy losses associated with storage water heaters, which can save you money.
Whether or not a tankless system is good for your requires a little thought. If you have a problem with instantaneous flow (e.g. you want to be able to run your washer, dishwasher, and have everyone take a shower simultaneously), a tankless system to meet your needs will likely be impractical. Your problem seems to be more length periods of continuous use, which would indicate that you could seriously benefit from a tankless system.
If you really need water > 140F, they probably aren't a good solution for you. The vast majority of homeowners however do not.
If all you care about is the dollars and cents of it, the solution is to get a couple of quotes from reliable contractors, look at your personal energy rates, and do the math. It's pretty easy math, but if you have trouble with it, I'll be glad to help.
If you care about energy conservation, then you can rest assured that you will be doing a good thing for the environment, you won't lose any money in the long run, and you might even profit from it. The latter case seems to be the most likely, in my analysis.
GS www.glenstark.net
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http://www.eere.energy.gov/consumer/your_home/water_heating/index.cfm/%20mytopic820 note it appears in homes that use more water, the typical 2 adults and 2 teenagers savings are less, probably because the standard tank spends more time heating water and less time standing by. this is a new wrinkle on the tank vs tankless discussion
For homes that use 41 gallons or less of hot water daily, demand water heaters can be 24%-34% more energy efficient than conventional storage tank water heaters. They can be 8%-14% more energy efficient for homes that use a lot of hot water--around 86 gallons per day. You can achieve even greater energy savings of 27%-50% if you install a demand water heater at each hot water outlet.
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http://www.eere.energy.gov/consumer/your_home/water_heating/index.cfm...
also note this word of warning
For example, taking a shower and running the dishwasher at the same time can stretch a demand water heater to its limit. To overcome this problem, you can install two or more demand water heaters, connected in parallel for simultaneous demands of hot water. You can also install separate demand water heaters for appliances--such as a clothes washer or dishwater--that use a lot of hot water in your home.
then 2 showers and a dishwasher at same time will require multiple tankless?
it also points out that a tankless with a pilot light can wipe out any savings.....
wonder if the posters here who say their tankless works in a power failure have tankless with pilot light? if so they arent saving anything......
given the tankless high BTU and the flue gas requirements wonder how many could afford multiple tankless around their home????????
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No, but it may require a larger, more expensive unit than 1 shower and a dishwasher at the same time. Personally I don't think dishwashers are a big issue, it's no problem to defer dishwasher/clothes washer use until the showering is done.

This shows the article is somewhat out of date. Tankless heaters with pilot lights are pretty old technology.
Cheers, Wayne
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Particularly now that washing machines are coming equipped with delayed start options.
Hey Haller, how come you're ignoring the link and quote I posted from the engineering trade journal about standby loss? Trade journals are rarely run by wacky bastards that print/post bad information. The author is an interesting guy: http://www.newyorker.com/archive/2003/03/17/030317ta_talk_sullivan
R
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Curious. It's just a damn 'hot' water heater. Why all the passion?
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Because it's a paradigm shift and those always bring discomfort.
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On Wed, 09 Apr 2008 14:50:31 -0700, Matt W. Barrow wrote:

My opinion is it's caused by a failing in the American educational system (I'm sure other countries have similar failings, but I'm only an expert on America). We don't learn analytical thinking, nor how to apply analytical thinking to practical everyday problems. We aren't taught to be critical consumers.
I studied physics, and TA'd freshman physics labs at Georgia Tech, a place where reasonably bright, reasonably well educated types go. They all knew the algebra necessary to solve the labs (it was 9'th grade level math), but it was extremely rare to find someone who would, without walking them through it, be able to take the simple physical problem and translate it into the simple mathematical equation, and then solve that equation.
American consumers, just like American voters (same people after all) are far more likely to make an emotional decision than a rational one, although a goodly number of them go to a lot of effort to rationalize their decisions afterward. Then they go to a lot of effort to justify their rationalizations, instead of being flexible and changing their minds about things as new information and technology arises (look at how much mileage Bush got out calling Kerry a 'waffler').
Because their decision making is emotional, they get emotional about justifying the decision, and it becomes next-to-impossible to argue with them. The more thoroughly you can prove that they are mistaken, the more pissed off they will get, and impossible to convince.
Additionally, as a culture want simple answers. We like to paint things in terms of good and evil, right and wrong. The water heater thing isn't so simple. Whether a tankless system is good for you depends on your use, and it's worth going over the facts and making an intelligent decision. On the other hand, the facts seem to indicate it is the right choice for the majority of people, not to mention the environment.
Finally, we're a pretty prideful people. Humility is not taught as a virtue in our culture. So we take it as a personal shortcoming, or a loss of face, when we are proven wrong. The more passionately we argue for something, the more face we lose if we change our mind. It's important to struggle against that mode of being since it leads to really sub-optimal solutions.
For my side,I would hope both this post and the previous one showed more a passion for analytical thinking and reasonable decision making than they do for tankless water heaters :)
glen www.glenstark.net
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i liove endless hot water and my 50 gallon high BTU tank provides over twice what my old 40 gallon 34,000 BTU one did. its a small luxury and my gas bill appeared unchanged after its install
another tankless issue is the ones with heat modulation, where the burners go up and down automatically. these changes can be so fast a temperature compensating shower valve may have trouble keeping up, and be terrible for someone without temperature control.
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