<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<font face="Helvetica, Arial, sans-serif">Triax & SCR are
controls that allow electric heaters (or lights) to operate at a
lower output than full capacity. They are essentially efficient
and better semi-conductor versions of the old fashion "dimmer" or
mechanical rheostat well suited to controlling AC current.<br>
<br>
Why do we use them? Most thermostats are on-off switches. They
turn on your 1500W baseboard heater when the temperature falls
below a certain point, and turn it off when it rises about another
temperature. Triac/SCR allows one to slowly ramp up the power to
a heater and then keep it at the required output. <br>
<br>
</font><font face="Helvetica, Arial, sans-serif">So, for example, a
baseboard of 1500W output may turn on for 10 minutes, then turn
off and the room cools down for 20 minutes, and then the cycle
repeats. The temperature falls to, say, 68F, the heater turns on,
the temperatures rises over the ten minutes to, say, 71 F, and the
switches off again.<br>
With a a modulating control like a Triac, a very smart thermostat
would attempt to adjust the output of the heater to 500W
continuously (because 500 Watts for 30 minutes </font>delivers
the same energy as 1500W for 10 minutes every 30 minutes). This
means the average current is lower, the electric heater runs at a
lower temperature, and the room temperature stays more constant.<br>
<font face="Helvetica, Arial, sans-serif"><br>
Anything that can change in a series of steps from off to on is
called "modulating" in the jargon of the industry. You could
often substitute the word "adjustable". Similarly we have
two-stage and three-stage furnaces that provide 2 or 3 steps of
output rather than one. We also have fully modulating furnaces
that provide many steps, sometimes an infinite number of steps
between off and full rated output. Modulating heat pumps have
many stages of output, some as many as 2000, which means output
can vary smoothly from off to full output and essentially any
output in between. Most main-brand North American heat pumps are
on-off, or at most two-stage. There are numerous technologies
that can be used to provide modulating output on heat pumps,
including inverters driving DC compressor motors, ECM compressors,
mechanical unloading of constant speed compressors, etc. Despite
claims by some (usually the people who sell them) inverter
technology is not fundamentally, or even often, the best way of
getting a heat pump to modulate. But it is cheap and widely
available.<br>
<br>
Modulating heat pumps are much more efficient than standard on-off
or even two-stage heat pumps because they can run for long steady
periods at lower than maximum loads, making their heat exchanger
coils much more efficient, and allowing for more efficient
operation of the compressor.<br>
Modulating electric heaters consume exactly the same amount of
energy as non-modulating, but may provide other benefits primarily
in old and inefficient buildings.<br>
<br>
NEST is a very fancy thermostat with an awful lot of technology,
most of which wont do much at all, and all of which is unnecessary
for anyone willing to get involved in understanding there home and
lifestyle. But it is pretty cool and I am sure many people will
buy them and love them. They just wont save much energy.<br>
<br>
<br>
</font>
<pre class="moz-signature" cols="0">Dr John Straube, P.Eng.
<a class="moz-txt-link-abbreviated" href="http://www.BuildingScience.com">www.BuildingScience.com</a></pre>
<br>
On 11-12-17 12:06 PM, Bob Jakaitis wrote:
<blockquote cite="mid:BAY167-DS239276F5CC01919A9F8028C8A10@phx.gbl"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<meta name="Generator" content="Microsoft Word 12 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal">Dr. John Straub wrote:<o:p></o:p></p>
<p class="MsoNormal">“Alas, triac or SCR control of electric
heaters does not save energy.”<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">John can you explain the differences
between:<o:p></o:p></p>
<p class="MsoNormal">“Modulating heat pumps” and “Triac or SCR
control” <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What do you think of the NEST “learning
thermostat” <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I recently read this article about Best Buy
running 3 pilot programs for home sustainiblity products do in
Chicago, Houston and San Carlos, Ca. : <o:p></o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://www.smartplanet.com/blog/business-brains/best-buy-ceo-sustainability-is-serious-business/19779">http://www.smartplanet.com/blog/business-brains/best-buy-ceo-sustainability-is-serious-business/19779</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">They have described a NEST “learning
thermostat” that has sold out online:<o:p></o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://www.bestbuy.com/site/olspage.jsp?id=1218396586516&type=product">http://www.bestbuy.com/site/olspage.jsp?id=1218396586516&type=product</a> <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://www.nest.com/living-with-nest/">http://www.nest.com/living-with-nest/</a><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Sincerely,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Bob
Jakaitis aka "Jake" <br>
NC General Contractor<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Air
Sealing and Energy Saving Services<br>
Jake at the Lake Development Inc.<br>
Tel: 704-236-3574<br>
Email: <a class="moz-txt-link-abbreviated" href="mailto:jake@jakeatthelake.com">jake@jakeatthelake.com</a><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">
<a class="moz-txt-link-abbreviated" href="mailto:greenbuilding-bounces@lists.bioenergylists.org">greenbuilding-bounces@lists.bioenergylists.org</a>
[<a class="moz-txt-link-freetext" href="mailto:greenbuilding-bounces@lists.bioenergylists.org">mailto:greenbuilding-bounces@lists.bioenergylists.org</a>]
<b>On Behalf Of </b>John Straube<br>
<b>Sent:</b> Saturday, December 17, 2011 9:38 AM<br>
<b>To:</b> Green Building<br>
<b>Subject:</b> Re: [Greenbuilding] Triac Thermostats<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Alas, triac or SCR control of electric
heaters does not save energy. This approach improves comfort
and reduces the peaks on the house circuit, prolongs heater
life span, reduces the burning smell, but does not save
energy.<br>
<br>
Modulating heat pumps (instead of the normal on-off)
dramatically improves efficiency as well as all the above
benefits. This is a huge difference.<br>
<br>
The grid does not benefit from a sub-division of houses on
tri-acs or standard on-off thermostats:once 20, 30 or 300
homes get averaged together, the peaks of individual units
dont make any difference. The grid cares about peaks due to
cold weather, or hot weather, when hundreds, thousands, even
millions of homes are on average demanding more power.<br>
<br>
Using a electric heating is hopefully only going to be used
for very small loads in the future as banning 1500W heaters in
buidings would be a good way to reduce peak demand on the
grid.<br>
<br>
<br>
Dr John Straube, P.Eng.<br>
<a moz-do-not-send="true"
href="http://www.BuildingScience.com">www.BuildingScience.com</a><br>
<br>
<br>
On 11-12-17 8:26 AM, Richard Garbary wrote:<br>
> Recently installed three triac<o:p></o:p></p>
<p class="MsoNormal"> thermostats in an all-baseboard<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > townhouse: rec-room/basement,
living room, master bedroom.<o:p></o:p></p>
<p class="MsoNormal"> The owner<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > is very pleased with the
results. Very accurate temperature<o:p></o:p></p>
<p class="MsoNormal"> control;<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > no wild swings above and below
the set point. The thermostats<o:p></o:p></p>
<p class="MsoNormal"> output<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > just enough wattage to match the
heat loss. A normal<o:p></o:p></p>
<p class="MsoNormal"> thermostat is<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > just a switch, either on or off.
Normal watt-density for<o:p></o:p></p>
<p class="MsoNormal"> baseboards<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > is 250 watts/foot. With the
triac, watt-density can be<o:p></o:p></p>
<p class="MsoNormal"> reduced to<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > less than 50 watts/foot. Like
heat pumps with inverter<o:p></o:p></p>
<p class="MsoNormal"> technology,<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > the object is to run the
appliance at the lowest power level,<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > continuously; this makes for a
very low demand on the grid.<o:p></o:p></p>
<p class="MsoNormal"> One of<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > the many benefits is that it
virtually eliminates "cold wall<o:p></o:p></p>
<p class="MsoNormal"> effect",<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > because the baseboards are not
cycling on and off.<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > This is a great upgrade solution
(interim or until the money<o:p></o:p></p>
<p class="MsoNormal"> comes in<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > for the heat pump!) for anyone
with baseboards. Just might<o:p></o:p></p>
<p class="MsoNormal"> breathe<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > new life into a heating method
that many have not considered,<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > especially in well insulated
homes.<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <a moz-do-not-send="true"
href="http://www.aubetech.com/support/faq.php?noLangue=2#TRIAC">http://www.aubetech.com/support/faq.php?noLangue=2#TRIAC</a><br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > Richard<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> >
_______________________________________________ Greenbuilding<o:p></o:p></p>
<p class="MsoNormal"> mailing<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > list to Send a Message to the
list, use the email address <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <a moz-do-not-send="true"
href="mailto:Greenbuilding@bioenergylists.org">Greenbuilding@bioenergylists.org</a><br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> > to UNSUBSCRIBE or Change your
List Settings use the web page<o:p></o:p></p>
<p class="MsoNormal"> <br>
<br>
<o:p></o:p></p>
<p class="MsoNormal"> ><o:p></o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org">http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org</a><o:p></o:p></p>
</div>
</blockquote>
</body>
</html>