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<body>Hello, I'm building a SDHW system and I wonder if there is there a way to control a pump depending on the temperature drop of a tank. To be more specific there are two requirements in order to control the pump:<div><ol style="list-style-type: decimal;"><li>Pump is disabled when tank temperature exceeds 90 C</li><li>When tank temperature drops 3 C the pump is enabled once again</li></ol><div><div>I tried making it using a controller but I can't find a way to compare the tank temperature to itself over a timestep.</div><div><div><div> Any suggestions whould be appreciated.</div></div></div></div></div><div><br /></div><div>Thank you in advance,</div><div>Christos Goulas</div><div>Democritus University of Thrace</div><div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br />
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