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<DIV><FONT face=Arial>Hi Kris,</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Sorry that the terminology is decidedly a bit confusing to
even my esteemed, clever, and resourceful fellow wrenches.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Most folks are familiar with a typical natural
draft, gas fired, storage tank, water heater. It has a burner. A
non-modulating burner. When the tank doesn't call for heat, the
main burner can just sit there doing nothing. In a 40 gallon tank
typically, 30,000 - 40,000 BTU/h, all 40,000 BTU/h on or nothing. The nothing is
_not_ the minimum fire rate. The nothing is off.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Every gas fired tankless water heater I have seen in the
US uses a modulating burner. When it is a _flow_ actuated machine a large flow
will bring on the high fire rate, ~200,000 BTU/h in the previous
thread example. A smaller flow will modulate that 200,000 BTU/h fire
rate downwards. When the flow reduces further, but
still something more than a trickle (technically the actuation flow) the
machine will fire at the minimum fire rate which varies from heater to heater
but to use the previously cited example ~10,000 to 20,000 BTU/h. Now, if you
have a _temperature_ actuated machine and you are already at set point the
heater just sits there, _not_ firing when set point water passes through the
tankless. The perfect backup companion for SDHW, IMHO. Not firing
(off) is not the same as a fire rate that modulates to
zero.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>As I said (or should have said) early on, the trick
to use a gas fired tankless for SDHW backup is when the solar heated
water needs just a tad more heat.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Class out. Enjoy the weekend.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Bill Loesch</FONT></DIV>
<DIV><FONT face=Arial>Solar 1 - Saint Louis Solar</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV>----- Original Message ----- </DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=solman@legacysolar.com
href="mailto:solman@legacysolar.com">Kristopher Schmid</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=re-wrenches@lists.re-wrenches.org
href="mailto:re-wrenches@lists.re-wrenches.org">'RE-wrenches'</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, September 17, 2010 11:12
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [RE-wrenches] On Demand
Heaters for SDHW</DIV>
<DIV><BR></DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN
class=078020716-17092010>Wayne,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN
class=078020716-17092010></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN class=078020716-17092010>Your
statement that "<FONT color=#000000>The unit will turn off automatically once
input water temp reaches its programed output temp." seems to contradict the
statement from Bill saying "<SPAN lang=EN>All tankless, including solar
compatible (heaters which modulate fire rate based on _inlet temperature_)
have a minimum fire rate which is well above
zero."</SPAN></FONT></SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN class=078020716-17092010><FONT
color=#000000><SPAN lang=EN></SPAN></FONT></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN class=078020716-17092010><FONT
color=#000000><SPAN lang=EN>Am i missing
something?</SPAN></FONT></SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN class=078020716-17092010><FONT
color=#000000><SPAN lang=EN></SPAN></FONT></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN class=078020716-17092010><FONT
color=#000000><SPAN lang=EN>Kris</SPAN></FONT></SPAN></FONT></DIV>
<DIV> </DIV><!-- Converted from text/plain format -->
<P>Legacy Solar<BR>864 Clam Falls Trail<BR>Frederic, WI
54837<BR>715-653-4295<BR>solman@legacysolar.com<BR>www.legacysolar.com </P>
<BLOCKQUOTE style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left><FONT
face=Tahoma>-----Original Message-----<BR><B>From:</B>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of </B>Wayne
Irwin<BR><B>Sent:</B> Friday, September 17, 2010 9:40 AM<BR><B>To:</B>
Wrenches<BR><B>Subject:</B> Re: [RE-wrenches] On Demand Heaters for
SDHW<BR><BR></FONT></DIV>In our off grid home I installed a Rinnai
propane tank less to support<BR>the double pump drain-back system and have
had no problems. <BR>The tips that I suggest are: that the tank less be
flushed out regularly, <BR>even when not being used in-order to reduce any
sediment. <BR>If the water is hard, add a softener or at least a micro
filter. <BR>Scale build up can also be a problem. <BR>If this tank less unit
is being used as a back up, turn it off unless needed.<BR>The unit will turn
off automatically once input water temp reaches its programed output
temp.<BR>However, the initial water flow is cold enough to trigger the unit
to fire-up, wasting <BR>100,000 btu's of fuel for a minute or
so.<BR><BR><BR><FONT color=#76923c>Wayne Irwin</FONT><FONT
color=#76923c><BR>Director of Engineering<BR></FONT><FONT color=#76923c>Pure
Energy Solar International Inc. </FONT><FONT color=#76923c><BR></FONT><FONT
color=#76923c></FONT><FONT color=#76923c>State Licensed Solar
Contractor</FONT><FONT color=#76923c><BR></FONT><FONT color=#76923c>License
# CVC56695 </FONT><BR><A
href="mailto:PureEnergySolar@hotmail.com">Wayne@PureEnergySolar.com</A>
<BR><A href="http://pureenergysolar.net/"
target=_blank>http://pureenergysolar.com</A> <BR><FONT color=#76923c>352
377-6527 Office</FONT><FONT color=#76923c><BR></FONT><FONT color=#76923c>352
336-3299 Fax</FONT><FONT color=#76923c><BR></FONT><FONT
color=#76923c></FONT><BR>
<P class=ecxecxecxEC_EC_EC_EC_EC_MsoNormal><FONT color=#76923c><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; FONT-SIZE: 10pt">The content of
this message is Pure Energy Solar Confidential. If you are not the intended
recipient and have received this message in error, any use or distribution
is prohibited. Please notify me immediately by reply e-mail and delete this
message from your computer system. Thank
you.</SPAN></FONT></P><BR><BR><BR><BR>> From:
solman@legacysolar.com<BR>> To: re-wrenches@lists.re-wrenches.org<BR>>
Date: Fri, 17 Sep 2010 09:01:30 -0500<BR>> Subject: Re: [RE-wrenches] On
Demand Heaters for SDHW<BR>> <BR>> It all depends on whether you are
talking financial payback or wise energy<BR>> use. The people who use the
least amount of hot water are the people who<BR>> will experience the
greatest energy use savings. They are a great option<BR>> for weekend
cabins since you don't have to remember to turn off the water<BR>> heater
when you leave and you don't have to wait for the tank to heat up<BR>>
when you return.<BR>> <BR>> Kris<BR>> <BR>> Legacy Solar<BR>>
864 Clam Falls Trail<BR>> Frederic, WI 54837<BR>> 715-653-4295<BR>>
solman@legacysolar.com<BR>> www.legacysolar.com<BR>> -----Original
Message-----<BR>> From: re-wrenches-bounces@lists.re-wrenches.org<
br>> [mailto:re-wrenches-bounces@lists.re-wrenches.org] On Behalf Of
Todd Cory<BR>> Sent: Thursday, September 16, 2010 1:55 PM<BR>> To:
RE-wrenches<BR>> Subject: Re: [RE-wrenches] On Demand Heaters for
SDHW<BR>> <BR>> <BR>> The payback on a demand heater in energy
savings is like 50+ years. A<BR>> traditional tank heater, super
insulated has very little loss.<BR>> <BR>> Todd<BR>> <BR>>
<BR>> <BR>> Peter Parrish wrote:<BR>> You’re right, Todd, there is
often a space limitation. But overall, the<BR>> tankless approach is more
economical, eliminating the need to keep 80 odd<BR>> gallons of water
perpetually up to temperature. Remember the solar heated<BR>> water is
"make up water" and can contribute to the temperature of the<BR>>
traditional water heater only while hot water is being used. So, my guess
is<BR>> that 1/2 of the day in a residence the traditional tank is
keeping water up<BR>> to temperature for no apparent use.<BR>>
<BR>> - Peter<BR>> <BR>> Peter T. Parrish, Ph.D., President<BR>>
California Solar Engineering, Inc.<BR>> 820 Cynthia Ave., Los Angeles, CA
90065<BR>> CA Lic. 854779, NABCEP Cert. 031806-26<BR>>
peter.parrish@calsolareng.com<BR>> Ph 323-258-8883, Mobile 323-839-6108,
Fax 323-258-8885<BR>> <BR>> <BR>>
________________________________________<BR>> From:
re-wrenches-bounces@lists.re-wrenches.org<BR>>
[mailto:re-wrenches-bounces@lists.re-wrenches.org] On Behalf Of Todd
Cory<BR>> Sent: Thursday, September 16, 2010 8:17 AM<BR>> To:
RE-wrenches<BR>> Subject: Re: [RE-wrenches] On Demand Heaters for
SDHW<BR>> <BR>> I know this was not the question, but this whole
thread is predicated on the<BR>> use of a demand hot water heater. Unless
there is a space limitation, why<BR>> would this be done over a
traditional tank unit?<BR>> <BR>> Todd<BR>> <BR>> <BR>>
<BR>> Bill Loesch wrote:<BR>&g t; <BR>> Kris,<BR>> <BR>>
Boiler manufacturers today get starry-eyed when their machines are able
to<BR>> provide a 10:1 turndown ratio. Even the venerable natural draft
Bosch 125BS<BR>> * provided a better than 4:1 turndown ratio and all the
condensing powervent<BR>> units compared below regularly offer 10:1 and
some better than 20:1. With<BR>> each benefit comes a disadvantage, like
with current production cars,<BR>> serious repair/maintenance takes place
primarily at the dealer since they<BR>> are usually the only ones to pony
up for the multitude of specialized test<BR>> equipment. I find it a bit
of backward progress to have to tell someone that<BR>> the reason they
don't have reliable hot water is because they don't have the<BR>> current
software update (due in no small part to the marketing gurus who<BR>>
have no qualms about using the customer as the proving grounds for
their<BR>> product). Many plumbers have no clue to the w orkings of a
combustion<BR>> analyzer, a necessary tool for negative pressure gas
valve tuning and<BR>> replacement (and a multitude<BR>> of other tasks
where the blue flame is no longer sufficient to be able to<BR>> deliver
optimum performance).<BR>> <BR>> Your Takagi needs AC power to (in
order of decreasing current requirements<BR>> for a generic power vented
tankless)<BR>> power the freeze protection heating elements<BR>> run
the primary combustion fan<BR>> run the secondary combustion fan<BR>>
provide control to<BR>> gas valve<BR>> water valve<BR>> control
board (oftentimes with digital display) which provides the<BR>> logic and
timing circuits for the multitude of sensors and limit switches<BR>> and
remote controls and wireless remote controls etc., etc.<BR>> <BR>>
Long live the thermocouple.<BR>> <BR>> My compliments on your
simplistic approach to coordinate the solar storag e<BR>> tank and
tankless. Simplicity is the ultimate sophistication.<BR>> <BR>> Bill
Loesch<BR>> Solar 1 - Saint Louis Solar<BR>> <BR>> <BR>>
<BR>> PS I reiterate, despite other RE-Wrenches list comments to the
contrary<BR>> about<BR>> "modulate to<BR>> zero", NONE of ANY of
the Big Five tankless manufacturers that market to<BR>> North America
have a low fire rate which modulates to zero or anything near<BR>> it for
the very same reason that you will never get a trickle of hot water<BR>>
out of any tankless water heater. (~0.5 gpm minimum activation flow<BR>>
requirement)<BR>> <BR>> Comparing condensing heaters with ~200,000 max
BTU/h input<BR>> Bosch GWH C 800 ES 19,900 BTU/h<BR>> Noritz NRC 111
11,000<BR>> Paloma no condensing heaters<BR>> Rinnai RC98HPe
9,500<BR>> Takagi T-H2 13,000<BR>> <BR>> Thanks for your patience,
I hope it was not too techn ical.<BR>> <BR>> ----- Original Message
----- From: "Peter Parrish"<BR>>
<peter.parrish@calsolareng.com><BR>> To: "'RE-wrenches'"
<re-wrenches@lists.re-wrenches.org><BR>> Sent: Tuesday, September
14, 2010 10:37 AM<BR>> Subject: [RE-wrenches] On Demand Heaters for
SDHW<BR>> <BR>> <BR>> <BR>> We have a SDHW client that wants to
replace his old water heater with<BR>> a new tankless water heater. We do
a SDHW system about once a year,<BR>> and only for clients that are
getting a PV system from us to begin<BR>> with. So this is not a<BR>>
big business line for us and we are behind the curve in terms of<BR>>
understanding the latest technologies.<BR>> <BR>> As I remember from
an excellent workshop that I took about four years<BR>> ago: when used in
conjunction with a SDWH system, the tankless heater<BR>> should<BR>>
<BR>> (1) Modulate heat input based on INPUT water temperature<BR>>
(2) Be able to modula te down to ZERO BTU/hr<BR>> <BR>> The only unit
I knew of back then was the Bosch 125BS (I believe).<BR>> Today I can't
find any bigger units that fit the above requirements.<BR>> <BR>>
Short of using two Bosch 125BS units in parallel, does anyone have a<BR>>
solution?<BR>> <BR>> - Peter<BR>> <BR>> Peter T. Parrish, Ph.D.,
President<BR>> California Solar Engineering, Inc.<BR>> 820 Cynthia
Ave., Los Angeles, CA 90065<BR>> CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish@calsolareng.com<BR>> Ph 323-258-8883, Mobile 323-839-6108,
Fax 323-258-8885<BR>> <BR>> <BR>> <BR>>
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<BR>> <BR>> --<BR>> <BR>> Todd Cory<BR>> KE6SXS<BR>>
toddcory@finestplanet.com<BR>> Mt. Shasta Energy Services<BR>> License
C-10 #811428<BR>> P.O. Box 689<BR>> Mt. Shasta, CA. 96067<BR>>
(530) 926-1079<BR>> <!--[if !supportEmptyParas]-->
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