[Greenbuilding] Water heaters( Marathon or standard electric)-study shows demand water heaters don't deliver.

Drew A. Gillett P.E. deaneg at hotmail.com
Mon Jan 15 18:38:29 CST 2007 

you brought up the study

http://www.rmi.org/images/other/Energy/E04-15_HEB5WaterHeat.pdf

, you should read it and particularly the footnoted study

 http://www.nahbrc.org/docs/MainNav/Energy/3831_hotwatersystems.pdf
on which it is based.

read the study in its entirety and you will see it is more about 
distribution systems than tank versus tankless and that it is false to 
conclude anything about the actual in place efficency or utility of tankless 
from this paper study.

carmine, i have no problem with your advocacy of gfx htx. i do have a 
problem with you coupling it unnecessarily with the hype surrounding 
tankless.

i reiterate that the best general solution is a solar tank with internal 
backup electric  with a gfx .  small short direct insulated piping  should 
be a given.
----- Original Message ----- 
From: "Dr. C.F. Vasile" <gfx-ch at msn.com>
To: "Drew A. Gillett P.E." <deaneg at hotmail.com>
Cc: "Green Building" <greenbuilding at listserv.repp.org>
Sent: Monday, January 15, 2007 3:45 PM
Subject: Re: [Greenbuilding] Water heaters( Marathon or standard 
electric)-study shows demand water heaters don't deliver.


>
>    How can you write "the study is suspect since it showed demand water 
> heater efficienciies over 100%"?
>    Are you confusing Energy Factor (EF) with a GFX with Efficiency?
>    As you may verify from the Old Dominion evaluation of several types of 
> electric water heaters, summarized in the Tables @ 
> http://www.gfxtechnology.com/tests.html, a GFX can boost the EF of any 
> electric water heater above 100% by feeding back power & energy normally 
> sent down-the-drain.
>
> ----- Original Message ----- 
> From: "Drew A. Gillett P.E." <deaneg at hotmail.com>
> To: "Carmine Vasile" <gfx-ch at msn.com>
> Sent: Sunday, January 14, 2007 2:05 PM
> Subject: Re: [Greenbuilding] Water heaters( Marathon or standard 
> electric)-study shows demand water heaters don't deliver.
>
>
>>i took a few moment to go to that page and the footnote 5 study from that 
>>and find that hi eff electic storage heaters are still the way to go 
>>given the high cost, performance and maintenance issues of the electric 
>>demand for a typical household of 4 with multiple simultaneous uses.
>>
>> the study is suspect since it showed demand water heater efficienciies 
>> over 100%
>>
>> the study is a simulation (with assumptions like 99% demand water htr 
>> efficiency) and is not a measurement of actual data in actual homes or 
>> even in the lab
>>
>> the study includes piping losses in the system efficiency which might be 
>> good overall, but is something the tank can do nothing about.  further if 
>> a tankless is used at the beginning of a distribution system ather than 
>> at the point of use, the piping losses still occur.  since these are 
>> roughly 20% of the system use, the major isssue is not tankless or tank, 
>> but rather point of use or piping distribution.   a solution is smaller 
>> pipes, parallleled and insulated. or better design of the piping layout 
>> so the usage point is near the tank--duh!
>>
>>
>> of some interest is the cost (see below) of the units to service in point 
>> of use manner a typical home, not including the 10 30 amp circuits 
>> required.
>>
>> Table 9. Configuration and Costs for Distributed Point-of-Use Water 
>> Heater System
>>
>>
>>
>> Flow
>>
>> Rate
>>
>> (gpm)
>>
>> Tcw Thw Unit Cost/
>>
>> Unit
>>
>> Water Heating
>>
>> Equipment
>>
>> Cost
>>
>> Number
>>
>> of 30A
>>
>> Circuits
>>
>> Laundry 3 60°F 120°F 28 kW $58513 $585
>>
>>
>> 4
>>
>>
>> Sinks
>>
>> (2)
>>
>> 0.5 60°F 110°F
>>
>> 2.5 gallon
>>
>> under
>>
>> sink
>>
>> $13514 $405 0
>>
>> Showers
>>
>> (2)
>>
>>
>>
>> 1.5
>>
>>
>> 60°F
>>
>>
>> 110°F
>>
>>
>> 11 kW
>>
>>
>> $38515
>>
>>
>> $770
>>
>>
>> 2 x 2 = 4
>>
>> Kitchen 1 60°F 120°F 9 kW $175 $175 2
>>
>> Total $1,935 10
>>
>>
>>
>>
>> 12. Installed System Cost
>>
>> 12.1 Whole-House Demand Water Heater
>>
>> For a central demand water heater, related NAHB Research Center work has 
>> shown that there is
>>
>> no additional plumbing cost for a demand water heater versus a tank-type 
>> water heater. There
>>
>> are, however, additional electrical costs for extra circuits, heavier 
>> gauge wire, and labor. Based
>>
>> on interviews summarized in Section 13, electrical costs increased by 
>> $250 and $350 for the
>>
>> demand unit (for running three extra 30A circuits). Equipment costs for 
>> whole-house electric
>>
>> demand water heaters range from about $585 to $850, whereas equipment 
>> costs for electric tank
>>
>> water heaters range from about $200 (for low-end equipment) to $600 (for 
>> a highly efficient
>>
>> water heater).
>>
>> also that rmi study is 3-4 years old and used gas prices from then. 
>> since then gas prices have doubled while electric has remained stable or 
>> gone down.  solar hot water with electric backup is the way to go.  of 
>> course you should always reduce the load first and a gfx like device  is 
>> a good start.
>>
>> basically the whole study appears to be a puff piece for demand water 
>> heaters when the answer is staring them in the face-  insulate the tank, 
>> insulate the pipes ( and make them smaller, shorter andpex), use a gfx, 
>> and use solar for the remaining energy required.
>>
>> in short, it pays to actually read the studies and assumptions.  if you 
>> do, they conclude that unless tankless are made point of use to reduce 
>> the piping losses, tanked electric with solar ( and a gfx) are the way to 
>> go. while remembering to insulate the pipes.
>>
>>
>> ----- Original Message ----- 
>> From: "Carmine Vasile" <gfx-ch at msn.com>
>> To: <wipfamly at hutchtel.net>; <greenbuilding at listserv.repp.org>
>> Sent: Sunday, January 14, 2007 10:39 AM
>> Subject: Re: [Greenbuilding] Water heaters( Marathon or standard 
>> electric)
>>
>>
>>> No; a tankless electric water heater is a much better & greener 
>>> investment.
>>> See RMI Home Energy Brief #5 @
>>> http://www.rmi.org/images/other/Energy/E04-15_HEB5WaterHeat.pdf; Table 1 
>>> for
>>> some comparisons.
>>>
>>> Why on God's not-so Green Earth would you install a 105 gallon 
>>> residential
>>> water heater costing $850? Your idea to by a cheap, inefficient 
>>> 50-gallon
>>> unit every 10 years is precisely what utilities encourage becaue as they 
>>> age
>>> their dip tubes have been known to disintigrate, which renders them
>>> exceptionally inefficient. Your coop is probably getting a kick-back for
>>> promoting expensive & wasteful tank-type water heaters. That's what 
>>> electric
>>> utilities do to justify bulding power plants & LNG terminals to accept 
>>> LNG
>>> from the Mideast!
>>>
>>>
>>>>From: "Tom Wiprud" <wipfamly at hutchtel.net>
>>>>To: <greenbuilding at listserv.repp.org>
>>>>Subject: [Greenbuilding] Water heaters( Marathon or standard electric)
>>>>Date: Sat, 13 Jan 2007 20:59:00 -0600
>>>>
>>>>I plan on building a new house soon.  I received the coop newsletter. 
>>>>They
>>>>had the 105 gallon Marathon, R25  leakproof  water heater for about 
>>>>$850.
>>>>
>>>>    My question is, would this be a good investment at $850, or would I 
>>>> be
>>>>better off  buying standard electric water heaters,(2 water heaters, 50
>>>>gallons each) and insulating them inside a box, and figure on replacing
>>>>them
>>>>in 10 years?   What are your opinions or suggestions?    Thanks    Tom
>>>>
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>>>
>>>
>>>
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>>
>>
>
>

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