[RE-wrenches] Electric Water kWh/ person

Tue Mar 20 14:06:18 EDT 2018

Ah,off grid. I see. That makes sense. I wouldn't use it place of solar, 
but we have used it as part of one. Obviously we have a tank in that 
application. We have a very good propane sales person herewho has sold a 
lot of on demand radiant and hydronic.It's almost twice thecost per BTU 
v oil, but they have done very well on low maintenance claims.

On 3/20/2018 1:58 PM, Dave Angelini Offgrid Solar wrote:
> Chris,
>
> For Offgrid with minerals in the well water, getting the right flow, the
> maintenance that is just not there with a tank heater. Tankless are great
> for many but if you do add an open loop solar water panel, you need a
> tank.... Just not worth it in places like the south west where there is
> abundant sunshine. Offgrid in remote places where service is questionable
> or unavailable, we go with the most reliable. I steer them that way for
> other reasons also..
>
> Dave Angelini Offgrid Solar
> "we go where powerlines don't"
> http://members.sti.net/offgridsolar/
> e-mail  offgridsolar at sti.net
> text 209 813 0060
>
>> What are the issues with tankless water heaters?Â  I have heard them
>> described as having "issues", but I haven't read anything that describes
>> what they are.Â  They are very popular where I live.Â  Any info? Thanks,
>> Chris
>>
>>
>> On 3/20/2018 1:07 PM, Dave Angelini Offgrid Solar wrote:
>>> And a big maybe for Offgrid where we like multiple ways to
>>> charge/heat/cool and make hot water. The default method is almost always
>>> the most reliable. For a typical home a 50 gallon propane tank water
>>> heater with a zinc change every 7 years is the norm.
>>>
>>> An air to water heat pump, an open loop solar water panel or closed loop
>>> if conditions warrant it are great secondary methods. To me heating
>>> water
>>> with electricity does not work because of winter and is a last thing to
>>> add.A tankless and their issues are near the end of the list. Ground
>>> source heat pumps are even lower to me with very nice prices on
>>> extremely
>>> efficient mini split air source pumps.
>>>
>>> I always try and minimize generators but if you need them then it allows
>>> one to have more options.
>>>
>>> Dave Angelini Offgrid Solar
>>> "we go where powerlines don't"
>>> http://members.sti.net/offgridsolar/
>>> e-mail  offgridsolar at sti.net
>>> text 209 813 0060
>>>
>>>> Maybe. I designed my own house to incorporate this. The most efficient
>>>> are
>>>> the vertical type, and at 6' the company advertised 20% recovery for
>>>> about
>>>> $1,300 if I remember correctly. This I'm sure is for a new copper pipe,
>>>> and
>>>> anyone who's ever taken apart a sewer pipe after a few years will know
>>>> all
>>>> pipes get a bacterial mat of a couple mm thick. I suspect this might be
>>>> a
>>>> pretty good insulator. At any rate there is a whole lot of copper
>>>> involved
>>>> and associated inherent environmental challenges. I can't help but
>>>> think
>>>> for the house design challenge to accommodate such a long perfectly
>>>> vertical pipe and expense another kW or more of solar would offset more
>>>> energy.
>>>>
>>>> On Tue, Mar 20, 2018 at 9:50 AM, Drake
>>>> <drake.chamberlin at redwoodalliance.org
>>>>> wrote:
>>>>> Daniel,
>>>>>
>>>>> That sounds like an intriguing technology, much along the lines of an
>>>>> air
>>>>> to air heat exchanger. Thanks for the recommendation.  These systems
>>>>> could
>>>>> keep a lot of CO2 out of the atmosphere if widely used.
>>>>>
>>>>> Drake
>>>>>
>>>>>
>>>>> At 10:09 AM 3/19/2018, you wrote:
>>>>>
>>>>> Content-Type: multipart/alternative;
>>>>>            boundary="----=_NextPart_000_0077_01D3BF6A.5EF88420"
>>>>> Content-Language: en-us
>>>>>
>>>>>
>>>>> Drake,
>>>>>
>>>>> Have you or the client looked into the drainwater heat recovery units?
>>>>> They make both a vertical and horizontal mounted version. They just
>>>>> help
>>>>> recover the waste heat from shower water going down the drain.
>>>>>
>>>>> My understanding is that economically they are barely past the
>>>>> breakeven
>>>>> point when considering offsetting grid power. If using PV costs as the
>>>>> benchmark, the economics would be better. If somehow this is off grid,
>>>>> then
>>>>> IÃ¢â‚¬â„¢d say itÃ¢â‚¬â„¢s a home run. (Hopefully though this is not
>>>>> an
>>>>> all-electric
>>>>> off-grid building.)
>>>>>
>>>>> The main benefit, as far as I understand it, is that you can get by
>>>>> with
>>>>> a
>>>>> smaller unit, with a smaller heating element to perform the same task,
>>>>> OR
>>>>> you can get much longer showers from the same sized unit. Depending on
>>>>> the
>>>>> clients goals, this might be a useful tool to bring into the
>>>>> situation.
>>>>>
>>>>> Here are two brand names that I know of.
>>>>> Vertical mount: renewability
>>>>> Horizontal mount: ecodrain
>>>>>
>>>>> I have not used these products, so I cannot endorse any of them, just
>>>>> though it may be worth consideration.
>>>>>
>>>>> With Regards,
>>>>>
>>>>> Daniel Young,
>>>>> NABCEP Certified PV Installation ProfessionalTM: Cert #031508-90
>>>>>
>>>>> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> *On
>>>>> Behalf Of *Drake
>>>>> *Sent:* Thursday, March 15, 2018 1:00 PM
>>>>> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
>>>>> *Subject:* Re: [RE-wrenches] Electric Water kWh/ person
>>>>>
>>>>> This discussion has been a great help. The house is built and the
>>>>> plumbing
>>>>> is in, but could be modified. Wood stoves are not a likely solution. I
>>>>> think we need a different water heating strategy.
>>>>>
>>>>> Thank you all!
>>>>>
>>>>> Drake
>>>>>
>>>>>
>>>>>
>>>>> At 09:21 AM 3/15/2018, you wrote:
>>>>>
>>>>> Content-Type: multipart/alternative;
>>>>>    boundary="------------EE4E9806B711DEF636076840"
>>>>> Content-Language: en-US
>>>>>
>>>>> This is what I came up with:
>>>>>
>>>>> The calculation is Q = mcp delta T
>>>>>
>>>>> Water Temp out =Ãƒâ€š  120
>>>>>
>>>>> Water Temp in = ground source Temperature @ 50F?
>>>>>
>>>>> delta T = 70F
>>>>>
>>>>> m =Ãƒâ€š  mass flow rate.Ãƒâ€š  ASHRAE is the source for this. 20gals
>>>>> per
>>>>> person
>>>>> per day = 20 gallons x 8.34 lbs/gallon =Ãƒâ€š  167lbs/day/person
>>>>>
>>>>> cp =Ãƒâ€š  1 BTU/lb-degree F
>>>>>
>>>>> Q = 167 x 1 x 70 = 11,676 BTU/day/person
>>>>>
>>>>> Divide this by the efficiency of the water heating system (I'll assume
>>>>> =
>>>>> .86)Ãƒâ€š  =11,676/.86 = 13, 577 BTU/person/day
>>>>>
>>>>> convert to kWh if necessarym 13,577/3412 = ~4 kWh/person/day, 120
>>>>> kWh/month
>>>>>
>>>>> I checked this against one month and it seems reasonable.
>>>>>
>>>>> Website assuming ~3.5 family size comes up with @ 400kWh per month.
>>>>> They
>>>>> approached it another way with assuming run times.
>>>>>
>>>>> https://www.google.com/search?safe=active&source=hp&ei=
>>>>> Z3KqWvXiNsGb5wKJ2Kf4DA&q=electric+water+heater+use+annual+consumption&oq=
>>>>> electric+water+heater+use+annually&gs_l=psy-ab.1.2.
>>>>> 33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.451.2360.
>>>>> 0j6j4j0j1.11.0....0...1c.1.64.psy-ab..18.16.1952.0..
>>>>> 0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI
>>>>>
>>>>>
>>>>> Chris
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 3/15/2018 8:09 AM, Mike Kocsmiersky wrote:
>>>>>
>>>>> Barton makes a good point with regards to the incoming ground water
>>>>> temperature and the amount of heat required to bring it up to shower
>>>>> temp.
>>>>> Ãƒâ€š My recollection is that ASHRAE states 20gal/person/day for the
>>>>> first
>>>>> 2
>>>>> people, then 15gpd or 12gpd thereafter.Ãƒâ€š  However those rates vary
>>>>> wildly
>>>>> with consumers, from those that never bathe to the high schooler that
>>>>> needs
>>>>> 3 showers a day.Ãƒâ€š  In the northeast water heating can be up to 19%
>>>>> of
>>>>> the
>>>>> total household energy load for the year.Ãƒâ€š  Also, I would
>>>>> recommend the
>>>>> air
>>>>> source heat pump water heaters if you have significant humidity or an
>>>>> on
>>>>> demand unit.Ãƒâ€š  Water tanks are typically under insulated and can
>>>>> lose
>>>>> 2kWh/day in standby losses.
>>>>> Ãƒâ€š
>>>>> Mike Kocsmiersky
>>>>> Principal
>>>>> Spirit Solar Inc.
>>>>> (413) 734-1456
>>>>> Ãƒâ€š
>>>>> Ãƒâ€š
>>>>> Ãƒâ€š
>>>>> From: Barton Churchill [mailto:barton at solarips.com
>>>>> <barton at solarips.com>]
>>>>> Sent: Wednesday, March 14, 2018 7:31 PM
>>>>> To: RE-wrenches
>>>>> Subject: Re: [RE-wrenches] Electric Water kWh/ person
>>>>> Ãƒâ€š
>>>>> You first need to know your ground temperature. Then figure a delta to
>>>>> 100
>>>>> or so degrees. Most but not all showerheads flow 2.5gpm and showers
>>>>> are
>>>>> typically 10 minutes. You can then find a calculator online to
>>>>> calculate
>>>>> how many Btus are required to raise water temp for your delta per
>>>>> gallon.
>>>>> Convert to kWh, add some contingency and you should be good.Ãƒâ€š
>>>>>
>>>>> On Wednesday, March 14, 2018, < drake.chamberlin at redwoodalliance.org>
>>>>> wrote:
>>>>> Hello Wrenches,
>>>>>
>>>>> Is there a good way to estimate the power that will be consumed for
>>>>> electric water per person per day? We are estimating the amount of
>>>>> power
>>>>> that will be used by an all electric duplex, and the water heater
>>>>> amount
>>>>> seems high. The current model we have claims 3493 kWh/ year per 26
>>>>> gallon
>>>>> tank will be consumed. With the two units, that would add up to 6986
>>>>> kWh
>>>>> /
>>>>> year for hot water, pushing the system size to humongous for a 1300 ft
>>>>> sq
>>>>> building.
>>>>>
>>>>> Does that seem high? There will be a maximum of 2 people per unit.
>>>>>
>>>>> The owner is considering going to 115 V units with a 15 gallon tanks.
>>>>> I
>>>>> think the smaller tank would help, but it would seem that the amount
>>>>> of
>>>>> hot
>>>>> water consumed would be the main issue.
>>>>>
>>>>> How can we get a good estimate for a per person energy usage for
>>>>> electric
>>>>> hot water? Any other suggestions are welcome.
>>>>>
>>>>> Thank you,
>>>>>
>>>>> Drake
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> --Ãƒâ€š
>>>>> Barton Churchill
>>>>> 406.587.5295 <(406)%20587-5295> Ãƒâ€š
>>>>> 2430 North 7th Bozeman, MT 59715
>>>>> www.solarips.com
>>>>> [image: Image removed by sender.]
>>>>> Ãƒâ€š
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>>
>>>>>
>>>>> List sponsored by Redwood
>>>>> Alliance
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> List
>>>>> Address:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> RE-wrenches at lists.re-wrenches.org
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Change listserver email address &
>>>>> settings:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> List-Archive:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> List rules &
>>>>> etiquette:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> www.re-wrenches.org/etiquette.htm
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Check out or update participant
>>>>> bios:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> www.members.re-wrenches.org
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š  Christopher Warfel,
>>>>> PE
>>>>> Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š  ENTECH Engineering, Inc.
>>>>> PO Box 871, Block Island, RI 02807
>>>>> Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š Ãƒâ€š
>>>>> Ãƒâ€š Ãƒâ€š Ãƒâ€š  (401)466-8978
>>>>> <(401)%20466-8978>
>>>>> Ãƒâ€š
>>>>> [image: EEI logo] <http://entech-engineering.com>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> List sponsored by Redwood Alliance
>>>>>
>>>>> List Address: RE-wrenches at lists.re-wrenches.org
>>>>>
>>>>> Change listserver email address & settings:
>>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>>>
>>>>> List-Archive:
>>>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.
>>>>> org/maillist.html
>>>>>
>>>>> List rules & etiquette:
>>>>> www.re-wrenches.org/etiquette.htm
>>>>>
>>>>> Check out or update participant bios:
>>>>> www.members.re-wrenches.org
>>>>>
>>>>> _______________________________________________
>>>>> List sponsored by Redwood Alliance
>>>>>
>>>>> List Address: RE-wrenches at lists.re-wrenches.org
>>>>>
>>>>> Change listserver email address & settings:
>>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>>>
>>>>> List-Archive:
>>>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.
>>>>> org/maillist.html
>>>>>
>>>>> List rules & etiquette:
>>>>> www.re-wrenches.org/etiquette.htm
>>>>>
>>>>> Check out or update participant bios:
>>>>> www.members.re-wrenches.org
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> List sponsored by Redwood Alliance
>>>>>
>>>>> List Address: RE-wrenches at lists.re-wrenches.org
>>>>>
>>>>> Change listserver email address & settings:
>>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>>>
>>>>> List-Archive:
>>>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.
>>>>> org/maillist.html
>>>>>
>>>>> List rules & etiquette:
>>>>> www.re-wrenches.org/etiquette.htm
>>>>>
>>>>> Check out or update participant bios:
>>>>> www.members.re-wrenches.org
>>>>>
>>>>>
>>>>>
>>>> --
>>>> --
>>>> Barton Churchill
>>>> 406.587.5295
>>>> 2430 North 7th Bozeman, MT 59715
>>>> www.solarips.com
>>>> _______________________________________________
>>>> List sponsored by Redwood Alliance
>>>>
>>>> List Address: RE-wrenches at lists.re-wrenches.org
>>>>
>>>> Change listserver email address & settings:
>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>>
>>>> List-Archive:
>>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>>>>
>>>> List rules & etiquette:
>>>> www.re-wrenches.org/etiquette.htm
>>>>
>>>> Check out or update participant bios:
>>>> www.members.re-wrenches.org
>>>>
>>>>
>>> Dave Angelini Offgrid Solar
>>> "we go where powerlines don't"
>>> http://members.sti.net/offgridsolar/
>>> e-mail  offgridsolar at sti.net
>>> text 209 813 0060
>>>
>>> _______________________________________________
>>> List sponsored by Redwood Alliance
>>>
>>> List Address: RE-wrenches at lists.re-wrenches.org
>>>
>>> Change listserver email address & settings:
>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>
>>> List-Archive:
>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>>>
>>> List rules & etiquette:
>>> www.re-wrenches.org/etiquette.htm
>>>
>>> Check out or update participant bios:
>>> www.members.re-wrenches.org
>>>
>>>
>> --
>>
>>   Â Â Â Â Â Â Â Â  Christopher Warfel, PE
>>   Â Â Â Â Â Â  ENTECH Engineering, Inc.
>> PO Box 871, Block Island, RI 02807
>>   Â Â Â Â Â Â Â Â Â Â Â Â Â Â  (401)466-8978
>>
>> EEI logo <http://entech-engineering.com>
>> _______________________________________________
>> List sponsored by Redwood Alliance
>>
>> List Address: RE-wrenches at lists.re-wrenches.org
>>
>> Change listserver email address & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>> List-Archive:
>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>>
>> List rules & etiquette:
>> www.re-wrenches.org/etiquette.htm
>>
>> Check out or update participant bios:
>> www.members.re-wrenches.org
>>
>>
>
> Dave Angelini Offgrid Solar
> "we go where powerlines don't"
> http://members.sti.net/offgridsolar/
> e-mail  offgridsolar at sti.net
> text 209 813 0060
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>
>

-- 

          Christopher Warfel, PE
        ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
                (401)466-8978

EEI logo <http://entech-engineering.com>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/attachments/20180320/be4371ec/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: EEIlogolong.jpg
Type: image/jpeg
Size: 17117 bytes
Desc: not available
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/attachments/20180320/be4371ec/attachment.jpg>