Basically what we're talking about with the efficiency of water heaters is
the percentage of the energy that's put into the system that actually gets
applied to the task of heating water. And, of course, a lot depends on where
you define the boundary of the system.
on a tankless feeding a regular tank, it should cost no more to
operate than a regular hot water tank.
the tankless initially heats the water to whatever it can, then sends
the water to a regular tank that does its normal job.
endless hot water regular tank conveniences and the only extra cost is
the line between the tankless and regular tank, ideally it should be
short and well insulated.
true the tank will have normal tank losses.
today i have to stop at home depot and while i am there price some hot
water tanks. just to verify some of these issues:)
Maybe not, but is sure costs a lot more in terms of buying and
installing 2 water heaters, one of which is tankless and more
expensive. With this approach, you incur the higher cost of tankless
and by having the second regular tank, you still have the standby
losses, which defeat most of the advantage of the tankless that
justify it's expense. I fail to see the point. Plenty of folks
have a gas tankless for their whole house needs and are happy with it.
There is no point to this approach, its backwards and will loose you
all the savings you just paid for. If the tankless and tank are 82%
efficent you are heating with one 82% burner and keeping it warm with
another 82% burner. You are heating with the tankless and allowing it
to cool in the tank, at about a 20% reduction in efficency rating.
Most of what you just paid for in increased efficency goes up the
center of the tank and out the chimney. The tank if hooked up should
before the tankless and only hold water unheated to allow it to warm
up by the surounding air to temper it, it works for me. Even better is
to strip of the insulation on the tank, your basement will always be
warmer then the incomming water main.
A much better way to do this is to get an electric tank water heater,
remove the heating elements, and wire the thermostat to run a pump on
a loop to the tankless heater. Incoming cold and outgoing hot are
from the tank iteslf.
This way, the standby losses are that of an electric tank, which is
less than a gas tank due to the lack of a flue down the middle. An
advantage over tankless only is that the delivered hot water pressure
is higher, because the pressure drop from a tank is noticeably less
than from a tankless.
When I get around to installing solar hot water, this is probably the
way I'm going to go; the solar can be on another loop from the tank.
On Tue, 18 Mar 2008 07:30:39 -0700 (PDT), ransley wrote:
I should have mentioned that I searched for that PDF during my GAS water
heater replacement. http://tinyurl.com/38eh4d
That PDF only contained residential GAS water heater specifications (very
many hundreds or even a thousand or more).
It did not have any residential ELECTRIC water heater efficiency ratings
(some of which approach 98% due to the fact no heat goes up the flue; it's
all absorbed by the water).
If you're gonna spend lots of money on a water tank you might as well
get an oil fired demand water heater. Gives you unlimited hot water and
no cost to maintain a tank of hot water. If you want to put a tempering
tank in your hot attic save even more.
my tankless add on was only for use when familiy is visiting, the
remainder of the time my 50 gallon high btu tank is fine.
now 7 people pile in here, and it can become a problem espically when
incoming water temperature is 40 degrees
Its alot of money to put in a tankless and not get the savings year
around, first you need to get the supply tested with all other gas
apliances running to be sure no upgrade is neded. Do 2 people shower
now at the same time, I dont think you will benefit having a tankless
before a tank and it will actualy cost more to run since both units
burners are probably near in efficency, I put my tankless after my
tank with bypass valves incase my old tank leaks, but i havnt used it
since installing the tankless, the cheap Bosch.
its more of a idle thought, the minor standby losses of a regular tank
dont bother me, and our tank is plenty big enough, except when family
visits. with washing clothes, doing laundry and showering its a busy
hot water using place. and our showers have the flow restrictors
but a new kitchen dining room gut job is a lot more likely and
probably better of use of money:) kinda nervous the economy may hurt
our income:( and gasoline is killing my service business
With shower restrictors removed you have to be real carefull, and
measure shower output since tankless are real specific on Gpm and the
amount of temp rise, [ on the coldest day, when gas pressure is low
and everything gas is on, water is 38f incomming] you still need a hot
shower. For many a cheap unit would not work, but I guess that really
depends on your incomming mains gpm.
On Sun, 16 Mar 2008 20:27:22 -0400, Don Wiss wrote:
A GUI is available to look up the efficiency of any water heater,
residential or commercial at http://www.gamapower.org
For example, residential hot water heater efficiency can be obtained at
Or, just call GAMA at 908-464-8200
What a poorly designed page! I gave up. Most annoying is each time you
return to the page to make a change it clears all your input away and you
have to reinput everything.
And it does not seem to include the model GPHE-50 (AO Smith Vertex) that I
just had installed.
Don <www.donwiss.com> (e-mail link at home page bottom).
Go to link - PDF file - pg. 15 (document page 217) 4th entry down for A.O.
Are you sure maybe you just arent searching correctly?
When you do a "Run Query" and it comes back with no results
DONT hit the back button on your browser.
Use the "Modify Query" on the page. It rolls back and there is all
your past info you typed.
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