Bryant 581B Ð PARABLADE Economizer Installed in Unit, Ð Panels Reinstalled On Unit

d.After installation is complete, calculate the mini- mum air¯ow across the economizer. To calculate the minimum air¯ow, the following data is needed:

total cfm (cfm3), temperature of the total cfm (T3), temperature of the return air (T2), and tempera- ture of the entering outside air (T1). Cfm1 is the outside air cfm, which will be the minimum air¯ow.

Insert the data into the following equations:

T1 (cfm1) + T2 (cfm2) = T3 cfm3

cfm2 = (cfm3 − cfm1) Therefore:

T1 (cfm1) + T2 (cfm3 − cfm1) = T3 cfm3

Use this equation to determine cfm1, which is the minimum air¯ow across the economizer.

cfm1 = (T3 −T2) cfm3 (T1 − T2)

If cfm1 does not match the desired minimum air- ¯ow from Step 1, readjust the minimum position setting screw.

7.Determine the enthalpy changeover set point from Fig. 27. The enthalpy changeover set point should be set to return the outdoor air damper to the minimum position when enthalpy rises above the set point. The settings are A, B, C, and D. Set the enthalpy change- over per the setting in Fig. 27.

8.Replace outdoor-air opening panel using screws from Step 2. Replace ®lter access panel. Ensure the ®lter access panel slides along the tracks and is securely en- gaged. See Fig. 28.

9.Fasten hood top and side plate assembly (Fig. 29) to outdoor-air opening panel with screws provided.

10.Slide outdoor-air inlet screen into screen track on hood side plate. While holding screen in place, fasten screen retainer to hood using screws provided. See Fig. 30.

Fig. 26 Ð PARABLADE Economizer Installed in Unit

CONTROL	CONTROL POINT
	(APPOX. DEG.)
CURVE
	AT 50% RH
A	73 (23)
B	70 (21)
C	67 (19)
D	63 (17)

Fig. 28 Ð Panels Reinstalled On Unit

Fig. 29 Ð Outdoor-Air Hood Installed On Unit

Fig. 27 Ð Enthalpy Settings for PARABLADE Economizer

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