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<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt">I
am getting ready to install my first ERV as my house step by step gets
tighter.<SPAN style="mso-spacerun: yes"> </SPAN>It is next on my list of
steps before I seal the deal (my occupied house).<SPAN
style="mso-spacerun: yes"> </SPAN>I have been reviewing last month’s
thread regarding ERV’s.<SPAN style="mso-spacerun: yes">
</SPAN><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office"
/><o:p></o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt"><o:p> </o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt">I
am still a little confused regarding the dehumidification affect of ERV’s.<SPAN
style="mso-spacerun: yes"> </SPAN><o:p></o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt"><o:p> </o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt"><A
title=steve@tjiang.org href="mailto:steve@tjiang.org">Steven Tjiang</A>
writes:<o:p></o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt">A
running ERV will still remove moisture from a house, just not as fast as an HRV
or an exhaust fan. ERVs slow down the increase in humidity in a well
sealed house when the exterior humidity exceeds that of the interior; and
decrease in humidity when interior humidity exceeds that of the
exterior. <o:p></o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt"><o:p> </o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt">My
comments:<o:p></o:p></SPAN></P>
<P style="MARGIN: 0in 0in 0pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 16pt">Dehumidifying
is primarily a benefit in the summer. We night flush our house in the
summer. Night times have a much higher relative humidity as cool air holds
less water. During the day when outdoor air temperature rises, the outside
relative humidity goes down. However, we close up the windows to
ventilation during the day which does for the most part keep the house
cooler. However, the relative humidity is higher than the outside
air. If outdoor air is cooled to indoor temperature, such as an ERV or
HRV, it will have a higher relative humidity. These ERV’s are transferring
real latent energy (water vapor) and not just relative humidity.<SPAN
style="mso-spacerun: yes"> </SPAN>If you mechanically cool your house
(AC), the air is cooled to below dew point when vapor condenses and physically
drains away.<SPAN style="mso-spacerun: yes"> </SPAN>At that point it has
100% relative humidity.<SPAN style="mso-spacerun: yes"> </SPAN>However,
the heat of house you are cooling heats that air which reduces the relative
humidity to achieve comfort.<SPAN style="mso-spacerun: yes"> </SPAN>A
dehumidifier reheats the air directly at the unit with the compressor heat.<SPAN
style="mso-spacerun: yes"> </SPAN>Therefore the indoor air is literally
dryer in # vapor/unit volume, not just relative humidity affected by air
temperature.<SPAN style="mso-spacerun: yes"> </SPAN>Then that actually
dryer indoor air regardless of temperature can dry the incoming fresh air by
latent transfer.<SPAN style="mso-spacerun: yes"> </SPAN>However, if the
air has not gone through a process of cooling to dew point where the water can
be physically removed from the air, the cooler high relative humidity indoor air
being exhausted will cool the hotter outside air to a higher relative
humidity.<SPAN style="mso-spacerun: yes"> </SPAN>Without an AC or
dehumidifier process removing the water from the air, can an ERV reduce
humidity?<SPAN style="mso-spacerun: yes"> </SPAN>Does it require a vapor
condensing equipment to dry the interior air to dry the exterior fresh air? If
not, does it have any advantages over a HRV where no latent transfers
occur?<SPAN style="mso-spacerun: yes">
</SPAN><o:p></o:p></SPAN></P></FONT>----- 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=steve@tjiang.org href="mailto:steve@tjiang.org">Steven Tjiang</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=satjiwan@alumni.brandeis.edu
href="mailto:satjiwan@alumni.brandeis.edu">satjiwan@alumni.brandeis.edu</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A
title=greenbuilding@lists.bioenergylists.org
href="mailto:greenbuilding@lists.bioenergylists.org">listserv Green Building
new</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, October 03, 2010 10:02
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Greenbuilding] ERV
strategy</DIV>
<DIV><BR></DIV>A running ERV will still remove moisture from a house, just not
as fast as an HRV or an exhaust fan. ERVs slow down the increase in
humidity in a well sealed house when the exterior humidity exceeds that of the
interior; and decrease in humidity when interior humidity exceeds that of the
exterior.
<DIV><BR>
<DIV>---- Steve (KZ6LSD)<BR><BR><BR>
<DIV class=gmail_quote>On Sun, Oct 3, 2010 at 6:44 AM, sat jiwan ikle-khalsa
<SPAN dir=ltr><<A
href="mailto:satjiwan_khalsa@hotmail.com">satjiwan_khalsa@hotmail.com</A>></SPAN>
wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote><BR>> From: Alan Abrams <<A
href="mailto:alan@abramsdesignbuild.com">alan@abramsdesignbuild.com</A>><BR>>
To: <A
href="mailto:ArchiLogic@chaffyahoo.ca">ArchiLogic@chaffyahoo.ca</A><BR><BR><BR>>
> Don't know nuttin' about nuttin' about ERVs (because MooseLand is
HRV<BR>> > Country but...<BR>> ><BR>> > Assuming that the
ERV is functioning similarly to an HRV in MooseLand<BR>><BR>> NO MOOSE
IN SLIGO CREEK, BUT HERE WHERE THE DEER SWARM LIKE STARLINGS, AND<BR>>
SUMMER R/H AND TEMPS EXCEED THE 90'S, THE ERV REMOVES SOME WATER VAPOR
FROM<BR>> INCOMING FRESH AIR<BR>><BR>><BR>> BUT EVEN DURING THE
SHOULDER SEASONS YOU WOULD WANT TO MECHANICALLY<BR>> DEHUMIDIFY THE
BATHROOMS<BR>><BR>> > ie the heating and cooling elements would
cycle on and off as heating or<BR>> > cooling demand dictates but
wouldn't the ventilation air demand remain<BR>> > somewhat constant
(ie except for those times when the fans kick into high<BR>> > speed
during a moisture or odour event) ?<BR>> ><BR>><BR>> JUST TO
CLARIFY, THE ERV'S UNDER CONSIDERATION ARE TWO STAGE. DURING
TIMES<BR>> WHEN THE MAIN SYSTEMS ARE REQUIRED, THE ERV WOULD RUN AT LOW
SPEED, AND<BR>> WOULD BE KICKED UP BY A TIMER SWITCH IN EACH BATHROOM.
DURING SPRING AND<BR>> AUTUMN, THE ERV WOULD BE RESET TO OPERATE
MANUALLY ONLY, USING THE TIMER<BR>> SWITCHES.<BR><BR>aren't we getting
caught up in the fallacy that ERV's dehumidify? they (at least mine)
don't have a condensate drain to "remove" humidity.<BR><BR>- my
understanding (and please correctmr if wrong) is that the HRV does
fresh air exchange while maintaining conditioned heat (at about 75%
efficiency, usually in colder, dryer climates).<BR>- the ERV does fresh air
exchange while maintaining whatever conditioned temperatures (heat and cool)
AND also doing something with latent heat in the humidity differential
inside and out. (i.e. it helps maintain whatever humidity you have
inside - achieved with separate air conditioners or dehumidifiers-- but does
not actually change the humidity of the indoor air. just does it's
best to make the outside air just as humid as the indoor air).<BR><BR>so
putting them on a bathroom doesn't make sense to me. extra humid air
in there will be equalized with incoming fresh air and tend to KEEP that
humidity inside the house. why is it that people use them
there?<BR><BR>~ ~ ~ ~ please use my permanent email address: <A
href="mailto:satjiwan@alumni.brandeis.edu">satjiwan@alumni.brandeis.edu</A>
~ ~ ~ ~<BR><BR><BR><BR>Some of my recent projects:<BR><BR>Takoma Area Green
Homes and Garden Tour - Saturday Oct 2, 2010, 11-5pm<BR>SEE: <A
href="http://www.Truthful-Living.com"
target=_blank>http://www.Truthful-Living.com</A><BR>Now (Low-volume)
Blogging at: <A href="http://truthful-living.blogspot.com/"
target=_blank>http://truthful-living.blogspot.com/</A> (as of
6/09)<BR> Green Building Consulting Services - Green Homes Tour -
(and free monthly column, green home building resource and energy
guide)<BR> Annotated green house renovation photos - <A
href="http://www.SaveOurSky.com" target=_blank>www.SaveOurSky.com</A> - corn
stove cooperatives - Takoma Park Green Building
Group<BR><BR><BR><BR><BR>_______________________________________________<BR>The
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