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

Mon Jan 15 14:45:27 CST 2007

    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
>>>
>>>_______________________________________________
>>>Greenbuilding email list
>>>List info:
>>>http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>>>List email: Greenbuilding at listserv.repp.org
>>>Managed by BuildingGreen, Inc. http://www.buildinggreen.com
>>>       publisher of Environmental Building News and GreenSpec(r)
>>>Hosted and archived by REPP / CREST http://www.crest.org
>>
>>
>>
>> _______________________________________________
>> Greenbuilding email list
>> List info: 
>> http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>> List email: Greenbuilding at listserv.repp.org
>> Managed by BuildingGreen, Inc. http://www.buildinggreen.com
>>      publisher of Environmental Building News and GreenSpec(r)
>> Hosted and archived by REPP / CREST http://www.crest.org
>>
>
>