Bryant 558D installation instructions Outdoor-Air Thermostat Enthalpy Control Installation

	0.90
	0.80
wg)(in.	0.70
	0.60
DROP
	0.50
PRESSURE
	0.40
	0.30
	0.20
	0.10
	0.00
		100	200	300	400	500	600	700	800
					CFM

Fig. 27 Ð Durablade Economizer Barometric Relief

Damper Characteristics

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)

cfm3

= T3

cfm2 = (cfm3 − cfm1) Therefore:

T1 (cfm1) + T2 (cfm3 − cfm1)

cfm3

= T3

							B	REV
								.
		MINIMUM						B
							C	1
								9
OPEN					D	S	TR	8
				S				8
					O			1
								8
		POSITION	1					A
	T	3
P
	T1	4	2	5
P1

30

60

70

AT

CONTACT

OR

CONTACTS

3

UH%

RUSH

ID IM

90

UNPOWERED

50

C

–

24VAC

YT

DAMPER

ATE

ENTHALPY

60

5A

2

10

D

CW

RATINGS:

ST SHOWN

TR

OUTDOOR

55

OPEN

B

SETPOINTS

24VAC

3 .

HIGH

A

1

IN

75

CLOSED DAMPER

mA

RUN,

TR1

CONTROL

F

VDC

1

TEMP

65 70

MIN

ENTHALPY

°

CCW

11

IN

–

.

3

.

AT

5A

.

80

85

REV.

97-3672

Fig. 25 Ð Outdoor-Air Thermostat/

Enthalpy Control Installation

OAT Ð Outdoor-Air Thermostat

NOTE: See unit wiring diagram for details.

Fig. 26 Ð Wiring Connections for Outdoor-Air Thermostat

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.

6.Determine the enthalpy changeover set point from Fig. 28. 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 changeover per the setting in Fig. 29.

7.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. 30.

8.Fasten hood top and side plate assembly (Fig. 31) to outdoor-air opening panel with screws provided.

9.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. 32.

NOTE: Refer to Fig. 33 for PARABLADE economizer baro- metric relief damper characteristics.

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