Controls, Start-Up, Operation, Service and ... - Climayoreo
Controls, Start-Up, Operation, Service and ... - Climayoreo
Controls, Start-Up, Operation, Service and ... - Climayoreo
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NOTE: If the user wishes to disable the st<strong>and</strong>ard enthalpy<br />
control from running concurrently, a field-supplied jumper<br />
must be installed between TB201 terminals 5 <strong>and</strong> 6.<br />
Outdoor Dewpoint Limit Check — If an outdoor relative<br />
humidity sensor is installed, the control is able to calculate the<br />
outdoor air dewpoint temperature <strong>and</strong> will compare this<br />
temperature against the outside air dewpoint temperature<br />
limit configuration (ConfigurationECONO.DEW). If the<br />
outdoor air dewpoint temperature is greater than O.DEW, free<br />
cooling will not be allowed. Fig. 12 shows a horizontal limit<br />
line in the custom curve of the psychrometric chart. This is the<br />
outdoor air dewpoint limit boundary.<br />
Custom Psychrometric Curves — Refer to the psychrometric<br />
chart <strong>and</strong> the st<strong>and</strong>ard Honeywell A-D curves in Fig. 11. The<br />
curves start from the bottom <strong>and</strong> rise vertically, angle to the left<br />
<strong>and</strong> then fold over. This corresponds to the limits imposed by<br />
dry bulb changeover, outdoor enthalpy changeover <strong>and</strong><br />
outdoor dewpoint limiting respectively. Therefore, it is now<br />
possible to create any curve desired with the addition of one<br />
outdoor relative humidity sensor <strong>and</strong> the options for changeover<br />
now available. See Fig. 12 for an example of a custom<br />
curve constructed on a psychrometric chart.<br />
Fig. 12 — Custom Changeover Curve Example<br />
69<br />
CONTROL POINT<br />
CONTROL CURVE<br />
(approx Deg) AT 50% RH<br />
A 73<br />
B 68<br />
C 63<br />
D 58<br />
Fig. 11 — Psychrometric Chart for<br />
Enthalpy Control