Carrier 48TJE008-014 Ð Durablade Economizer Barometric Relief, Damper Characteristics

dampers should be fully closed. Turn the potentiom- eter gradually counterclockwise until the desired po- sition is reached.

c.Connect T and T1 to the 24 v power supply.

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), tem- perature of the return air (T1), and temperature of the entering outside air (T2). Cfm1 is the return 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 mini- mum air¯ow across the economizer.

(T3 ± T2) cfm3

cfm1 =

(T1 ± T2)

Fig. 28 Ð Durablade Economizer Barometric Relief

Damper Characteristics

OPTIONAL PARABLADE ECONOMIZER Ð The op- tional PARABLADE economizer hood assembly is pack- aged and shipped in the ®lter section. Damper blades and control boards are installed at the factory and the econo- mizer is shipped in the vertical discharge position.

NOTE: Horizontal discharge block-off plate is shipped with the air hood package. The PARABLADE economizer can only be used for vertical discharge applications. Discard this plate.

Assembly

1.Determine if ventilation air is required in building. If so, determine the minimum amount to be supplied by each unit and record quantity of ventilation air needed for use in Step 7.

2.Remove ®lter access panel by raising panel and swing- ing panel outward. Panel is now disengaged from track and can be removed. No tools are required to remove ®lter access panel. Remove outdoor-air opening panel. See Fig. 18. Save panels and screws. Remove optional economizer so the outdoor-air damper hood package can be removed from the ®lter section.

3.Assemble outdoor-air hood top and side plates as shown in Fig. 19. Install seal strips on hood top and sides. Put aside screen retainer and retainer screw for later assem- bly. Do not attach hood to unit at this time.

4.On 012 and 014 units, install vertical discharge block- off plate over duct openings. See Fig. 20.

5.Slide economizer into unit and secure with screws. See Fig. 29.

NOTE: Be sure to engage rear economizer ¯ange under tabs in vertical return-air opening.

6.Insert economizer plug into economizer harness. Re- move tape from barometric relief damper. See Fig. 29.

7.If ventilation air is not required, proceed to Step 8. If ventilation air is required, perform the following:

a.Make sure the factory-installed jumper is in place across terminals P and P1 on the economizer logic module. T and T1 should be disconnected during adjustment.

b.The 2 potentiometers with slots for adjustment are located on the face of the economizer logic module. Turn the lower potentiometer fully clockwise. The

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

8.Determine the enthalpy changeover set point from Fig. 30. The enthalpy changeover set point should be set to return the outdoor air damper to the minimum po- sition when enthalpy rises above the set point. The set- tings are A, B, C, and D. Set the enthalpy changeover per the setting in Fig. 30.

9.Replace outdoor-air opening panel using screws from Step 2. Replace ®lter access panel. Ensure the ®lter ac- cess panel slides along the tracks and is securely en- gaged. See Fig. 31.

10.Fasten hood top and side plate assembly (Fig. 32) to outdoor-air opening panel with screws provided.

11.Slide outdoor-air inlet screens into screen track on hood side plate. While holding screens in place, fasten screen- retainer to hood using screws provided. See Fig. 33.

ECONOMIZER CONTROL

MODULE/DAMPER ACTUATOR

WIRING	ENTHALPY	BAROMETRIC
HARNESS	SENSOR	RELIEF DAMPER

Fig. 29 Ð PARABLADE Economizer Installed in Unit

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