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<p><font face="Verdana">What are the issues with tankless water
heaters<font face="Verdana">? I have heard them described as
having "issues", but I haven't read anything that <font
face="Verdana">describes <font face="Verdana">what they
are. They are very popular where I live. Any in<font
face="Verdana">fo<font face="Verdana">? Thanks, Chris</font></font></font></font></font></font><br>
</p>
<br>
<div class="moz-cite-prefix">On 3/20/2018 1:07 PM, Dave Angelini
Offgrid Solar wrote:<br>
</div>
<blockquote type="cite"
cite="mid:2b382aeb2337726f47e198ea4c380a17.squirrel@webmail.sti.net">
<pre wrap="">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"
<a class="moz-txt-link-freetext" href="http://members.sti.net/offgridsolar/">http://members.sti.net/offgridsolar/</a>
e-mail <a class="moz-txt-link-abbreviated" href="mailto:offgridsolar@sti.net">offgridsolar@sti.net</a>
text 209 813 0060
</pre>
<blockquote type="cite">
<pre wrap="">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
<<a class="moz-txt-link-abbreviated" href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a>
</pre>
<blockquote type="cite">
<pre wrap="">wrote:
</pre>
</blockquote>
<pre wrap="">
</pre>
<blockquote type="cite">
<pre wrap="">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
Iâ\u20ac\u2122d say itâ\u20ac\u2122s 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 <a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches-bounces@lists.re-wrenches.org"><re-wrenches-bounces@lists.re-wrenches.org></a> *On
Behalf Of *Drake
*Sent:* Thursday, March 15, 2018 1:00 PM
*To:* RE-wrenches <a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a>
*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 =Ã\u201a 120
Water Temp in = ground source Temperature @ 50F?
delta T = 70F
m =Ã\u201a mass flow rate.Ã\u201a ASHRAE is the source for this. 20gals per
person
per day = 20 gallons x 8.34 lbs/gallon =Ã\u201a 167lbs/day/person
cp =Ã\u201a 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)Ã\u201a =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.
<a class="moz-txt-link-freetext" href="https://www.google.com/search?safe=active&source=hp&ei=">https://www.google.com/search?safe=active&source=hp&ei=</a>
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.
Ã\u201a My recollection is that ASHRAE states 20gal/person/day for the first
2
people, then 15gpd or 12gpd thereafter.Ã\u201a However those rates vary
wildly
with consumers, from those that never bathe to the high schooler that
needs
3 showers a day.Ã\u201a In the northeast water heating can be up to 19% of
the
total household energy load for the year.Ã\u201a Also, I would recommend the
air
source heat pump water heaters if you have significant humidity or an on
demand unit.Ã\u201a Water tanks are typically under insulated and can lose
2kWh/day in standby losses.
Ã\u201a
Mike Kocsmiersky
Principal
Spirit Solar Inc.
(413) 734-1456
Ã\u201a
Ã\u201a
Ã\u201a
From: Barton Churchill [<a class="moz-txt-link-freetext" href="mailto:barton@solarips.com">mailto:barton@solarips.com</a>
<a class="moz-txt-link-rfc2396E" href="mailto:barton@solarips.com"><barton@solarips.com></a>]
Sent: Wednesday, March 14, 2018 7:31 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Electric Water kWh/ person
Ã\u201a
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.Ã\u201a
On Wednesday, March 14, 2018, < <a class="moz-txt-link-abbreviated" href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a>>
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
--
--Ã\u201a
Barton Churchill
406.587.5295 <(406)%20587-5295> Ã\u201a
2430 North 7th Bozeman, MT 59715
<a class="moz-txt-link-abbreviated" href="http://www.solarips.com">www.solarips.com</a>
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Ã\u201a
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Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Christopher Warfel, PE
Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a ENTECH Engineering, Inc.
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Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a Ã\u201a (401)466-8978
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<pre wrap="">
--
--
Barton Churchill
406.587.5295
2430 North 7th Bozeman, MT 59715
<a class="moz-txt-link-abbreviated" href="http://www.solarips.com">www.solarips.com</a>
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<pre wrap="">
Dave Angelini Offgrid Solar
"we go where powerlines don't"
<a class="moz-txt-link-freetext" href="http://members.sti.net/offgridsolar/">http://members.sti.net/offgridsolar/</a>
e-mail <a class="moz-txt-link-abbreviated" href="mailto:offgridsolar@sti.net">offgridsolar@sti.net</a>
text 209 813 0060
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<font size="-1"> Christopher Warfel, PE<br>
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