Table 100: Four-stage board - heat safety circuit
Location Label Description Function and comments
LIM2
Monitored 24 VAC input through heat section limit
switches
If voltage is absent, indicating the heat section is over temperature, the UCB will bring on the
indoor blower
GV2 24 VAC hot input confirming heat section operation
Sourced from gas valve 2 in. gas heat units or second stage heat contactor in electric heat units.
Input within 5 min from initiation of H2 output initiates the Heat On Fan Delay timer, loss of input
following the termination of H2 output initiates the Heat On Fan Delay timer, no input within 5 mi
from initiation of H2 output initiates an Ignition Failure alarm, input for longer than 5 min without
H2 output initiates a Gas Valve Mis-wire alarm
LIM3
Monitored 24 VAC input through heat section limit
switches
If voltage is absent, indicating the heat section is over temperature, the UCB will bring on the
indoor blower
J
GV3,4 24 VAC hot input confirming heat section operation
Table 101: Four-stage board - hot water safety quick connects and thermostat inputs
Location Label Description Function and comments
FS HWR Flow switch for Hydronic heat – 24VAC hot output Flow switch interlock for hot water coil
K
FS HW Flow switch for Hydronic heat – 24VAC hot return Flow switch interlock for hot water coil
Y3 3rd stage cooling request, 24 VAC input switched from R
Visible in the display menu when the #ClgStgs parameter is set to 4, also effective for
economizer free cooling supply air temperature reset when the #ClgStgs parameter is set to 4
Y4 4th stage cooling request, 24 VAC input switched from R
Visible in the display menu when the #ClgStgs parameter is set to 4, also effective for
economizer free cooling supply air temperature reset when the #ClgStgs parameter is set to 4
L
W3 3rd stage heating request, 24 VAC input switched from R Not effective for cooling-only units
Cable recommendations
Table 102: Cable type for FC buses and SA buses in order of preference
Non-plenum applications Plenum applications
Bus and cable type
Part number O.D. Part number O.D.
1
FC Bus: 22 AWG stranded, 3-wire twisted shielded cable
1
Anixter:
CBL-22/3-FC-PVC
Belden
®
: B5501FE
0.138 in.
Anixter: CBL-22/3-FC-PLN Belden:
B6501FE
0.140 in.
SA Bus (Terminal Block): 22 AWG stranded, 4-wire, 2 twisted-pair shielded cable
Anixter:
CBL-22/2P-SA-PVC
Belden: B5541FE
0.209 in.
Anixter: CBL-22/2P-SA-PLN
Belden: B6541FE
0.206 in.
SA Bus (Modular Jack):
2
26 AWG solid 6-wire, 3 twisted-pair cable
2
— —
Anixter preassembled: CBL-
NETWORK25 CBL-NETWORK50 CBL-
NETWORK75 CBL-NETWORK100
0.15 in.
FC Bus: 22 AWG stranded, 3-wire twisted non-shielded cable Belden: B5501UE 0.135 in. Belden: B6501UE 0.131 in.
SA Bus (Terminal Block): 22 AWG stranded, 4-wire, 2 twisted-pair non-shielded
cable
Belden: B5541UE 0.206 in. Belden: B6541UE 0.199 in.
1 We strongly recommend 3-wire (for FC bus) and 4-wire, 2 twisted-pair (for SA bus), 22 AWG stranded, shielded cable. A 22 gauge
cable offers the best performance for various baud rates, cable distances, and number of trunk devices primarily due to lower
conductor-to-conductor capacitance. Shielded cable offers better overall electrical noise immunity than non-shielded cable.
Observe the shield grounding requirements.
2 We recommend 26 AWG solid, 6-wire (3 twisted pairs) cable as the best fit for fabricating modular cables with the modular jack
housing assembly. Be sure the cable you use fits the modular jack housing. The preassembled cables that are available from
Anixter (Part No. CBL-NETWORKxxx) use 24 gauge wire.
Installation Manual: YORK
®
Sun
™
Select YV28 to YV50
103
Johnson Controls Ducted Systems
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