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Michael,<br>
What you are seeing isn't wrong; it is how actual HVAC systems
work. Thermostats have a deadband. They don't turn on heating until
the room temperature drops slightly below the set point and they
keep heating until the room temperature is slightly above the set
point. Usually the deadband is 1 or 2C. <br>
<br>
I think that what you are running into is difficulty in changing
setpoints, not in anything that has to do with hysteresis. Type108's
set points are inputs so you can set them to 21 during the day and
18 at night. You can define a Type14 that sets the set point as a
function of time or you can use Type514 from the TESS Applications
library.<br>
Best,<br>
David<br>
<br>
<br>
<div class="moz-cite-prefix">On 11/22/2012 06:43, Michael Diekerhof
wrote:<br>
</div>
<blockquote
cite="mid:trinity-44afa70e-be5d-4aac-93b5-fb5d7bf36ed9-1353588188901@3capp-webde-bs40"
type="cite">
<div style="font-family: Verdana;font-size: 12.0px;">
<div>Dear all,<br>
</div>
<div><br>
</div>
<div>I´m using Type 2d to turn on my heat pump (type401) in case
of the roomtemperatur falls below 18°C and to turn it off, if
Troom is >21°C.<br>
</div>
<div><br>
</div>
<div>My basic parameters are:<br>
</div>
<div><br>
</div>
<div>Upper input value = 0<br>
</div>
<div>Lower input value = Troom<br>
</div>
<div>Upper dead band = -18<br>
</div>
<div>Lower dead band = -21<br>
</div>
<div><br>
</div>
<div>This works fine but the problem is just that Troom always
fluctuates between 21 and 18 like a sawtooth function. The
same result appears if i use type108. Of course this is a
result of the hysterese but i would like to keep the
roomtemperature on a certain level depending on the daytime.<br>
</div>
<div><br>
</div>
<div>But how can i adjust that the set roomtemperature should be
20°C during the day and 18°C at night ??????<br>
</div>
<div><br>
</div>
<div>As i worked with type23 (PID Controller) I used type 14 and
an equation to give a setpoint to type23. <strong>But how can
i give a setpoint to type2d or type108 since there´s no
input variable for that ?<br>
</strong></div>
<div><strong></strong><br>
</div>
<div><strong></strong>I would appreciate any kind of help<br>
</div>
<div><br>
</div>
<div>best,<br>
</div>
<div><br>
</div>
<div>Michael <br>
</div>
</div>
<br>
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<br>
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<br>
<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
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