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

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wrote:

Don't forget the ashes! Ashes lend a certain 'ambiance' to ascetics.

BING! BING! BING!
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I don't think that is actually true--the marginal efficiency is about the same for a tank and tankless, assuming comparable combustion technology (i.e. both 80% non-condensing). The tankless wins by eliminating the fixed standby costs which are basically independent of usage. So you could rephrase your statement as "with a tankless someone could choose to spend some of their savings on a longer shower, and still come out ahead, if it isn't too much longer."
Cheers, Wayne
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So, you don't compute standby loss dollars in your scenario... Any other actual dollars spent that don't count in your theoretical calculations? Maybe you should rewrite what you wrote. I stand by what I wrote and, judging from your editing, I'm also a better writer. :)~
R
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No, it's not that the standby losses don't count, it's that they don't depend on usage. I guess I read your original statement as being one about incremental usage costs, in which case they don't appear. But apparently you were referring to average usage costs, where they do.
Cheers, Wayne
P.S. Analytically, what I'm saying is that a tankless will cost R * U dollars/month, where U is the usage in gallons/month and R is a rate in $/gallon. While the tank will cost you S + R * U, for the same rate R, where S is the dollar cost per month of the standby losses.
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And it loses due to startup time and people turning on the tap and doing something else waiting for the hot water to be generated.
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Startup time for hot water is dominated by the piping length between the heater and the point of use. The tankless adds at most 2 seconds to the startup time. For a 2.5 gpm shower, that's less that 0.1 gallons. A small effect.
Cheers, Wayne
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On 2008-04-13, AZ Nomad wrote:

We must be talking about different technologies. On my modern (2006) gas tankless unit, it is about 2 seconds. Maybe 3 seconds.
Cheers, Wayne
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Give em a bone, add 3-5 seconds to heat from 40 -110, maybe its longer , but not by much or EF rating would be alot worse than burner efficency.
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Really a full minute, not on mine, mine fires in 2 seconds after water is turned on, probably another 3-5 seconds to fully heat output. I say you are unqualified to respond to tankless. I dont realy notice a difference from the changeover, Pipe length from heater to faucet is the issue. Your Full Minute statement is untrue, the issue is cold water in the pipes already. Im now at a tank location, about 40 seconds I need to get HW out of 50 ft of pipe. The tankless location with about 15 ft is maybe 10 seconds 10 or so to push out cold water.
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Looking at the long-term situation....
http://www.thestar.com/Business/article/413800
Cheers, Paul
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my my tank vs tankless is now hotter than K&T and insurance difficulties........
lets have a group hug, no groping!!!!
so all those concerned with standby losses do you turn your vehicle off at long lights?
one day every new home will be required by law to be superinsulated, which could drop heating costs to near nothing
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On Sun, 13 Apr 2008 14:33:37 -0700 (PDT), " snipped-for-privacy@aol.com"

That day better come soon. I'm told Alberta's natural gas production is 12 billion cubic feet per day and 1 billion of that is currently used by the province's tar sands operation. The NEB is forecasting production to fall to 9 BCFD by 2012, at a time when 6 BCFD -- a full two-thirds -- will be used by the tar sands, in large part to power the new SAGD (Steam Assisted Gravity Drainage) plants now under construction. That suggests our natural gas supplies for domestic use (and export to the United States) will fall from 11 BCFD today to as little as 3 BCFD in less than five years.
Cold showers for everyone!
Cheers, Paul
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The sky is falling! The sky is falling!
jeeeze......

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On Mon, 14 Apr 2008 10:13:58 -0500, "S. Barker"

I'm also predicting gasoline will hit $2.00 a gallon... umm, on second thought, make that $3.00 a gallon... no, wait!... $4.00 a gallon.
Cheers, Paul
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Ya, really. I get a great big laugh everytime i hear someone say "gas will be $4 a gallon by the end of summer". YA YA, you been telling me that for 7 years now. Some day they will be right... LMMFAO!!
s

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Well, for those living in San Francisco the wait won't be long. According to the AAA, the average cost of regular unleaded is $3.929, up from $3.758 a month ago; mid grade and premium are selling at $4.181 and $4.249 respectively and diesel is $4.422.
The wait is already over in Hawaii where regular gas in Wailuku sells for $4.072. But since Hawaii is not part of the United States, it doesn't count, right?
Cheers, Paul
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wrote:

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I usually go by the official national average. You could hardly call CA or HI a normal place.
s
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wrote:
I'm sure the citizens of CA and HI will be amused to hear that.
Be that as it may, the AAA national average for regular unleaded is now $3.386; mid-grade and premium are $3.596 and $3.725 respectively. Diesel is selling for $4.119.
Crude oil is currently trading in excess of $113.50 a barrel and if the EIA's inventory numbers fall again tomorrow we can expect more turmoil in the oil markets. Refiners are not in the business to lose money, so either wholesale gasoline prices will rise or they'll simply cut back on production -- either way, retail prices will increase to reflect the higher cost of this more expensive crude.
Cheers, Paul
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