York W)036 THRU 060 Specifications download pdf (Page 46)

542300-YIM-A-1009

46 Johnson Controls Unitary Products

over and the UCB will de-energize the blower for 45 seconds.

However, the auxiliary limit is in series with the primary limit

and it takes first control. If the excessive heat has been high

enough to cause the auxiliary limit (AUX) to open, then the

ICB will flash the primary limit code but the furnace will not

retry ignition during the same call for heat. The auxiliary limit is

of the manual reset type and is mounted in the upper right

hand corner of the panel between the burner manifold and the

flue gas collector box just behind the draft motor. If the

auxiliary switch has opened, then special attention should be

paid to the primary limit as it may be faulty as well. However,

the auxiliary switch is sized such that multiple trips of the

primary limit due to complete blower failure will cause enough

heat to build up and trip the auxiliary.

If the primary limit opens three times within one hour, then the

UCB will lock on the indoor blower and flash a fault code

(Table 25).

Gas Valve

The UCB monitors the gas valve (GV). Any time the UCB senses

voltage at the GV without a call for heat for a continuous five-

minute period, the UCB will lock on the indoor blower and a flash

code on the UCB is initiated (Table 25). When the UCB no longer

senses voltage at the GV the UCB will de-energize the indoor

blower after the expiration of the indoor blower heating off delay.

If the voltage has been sensed at the GV for at least 15

seconds during the fan on delay for heating and the UCB no

longer senses voltage at the GV (W1 call for heat removed or

an ICB fault exists), then the UCB forces the indoor blower on

for the indoor blower heating off delay.

The gas valve is of the redundant type. If for any reason the

main gas valve fails in the open position, then the redundant

valve ahead of the main gas valve will shut off the flow of gas to

both the pilot and main gas valves.

Centrifugal Switch

The centrifugal switch is mounted on the end of the draft motor

and it is an integral part of the motor assembly. On a call for

heat, the ICB checks the centrifugal switch (CS) for open state

before it energizes the draft motor. If it is closed, then the ICB

will lock out the furnace and flash a code (Table 26). If open,

then the ICB will energize the draft motor and verify that the

switch closes before initiating the purging and ignition

sequence. If at any time during furnace operation the

centrifugal switch opens, then the ICB will de-energize the pilot

and main gas valves and monitor the centrifugal switch. If the

centrifugal switch closes and the call for heat still exists, then

the ICB will retry the purging and ignition sequence.

Rollout Switch

This temperature sensitive switch is located in the burner

vestibule just above the right hand side of the burner assembly.

In the event of the flame spilling out into the burner manifold

area the rollout switch will open, the ICB will close both the

main and pilot gas valves and flash a code (Table 26). The ICB

will not retry the ignition sequence during the same call for heat.

Flame Sense Circuit

The flame sensor is mounted on the left hand side of the burner

assembly and is positioned such that the pilot flame surrounds

the tip of the sensor. On a call for heat the ICB checks for the

flame sense circuit to be open. If open, then the ICB initiates the

purging and ignition sequence. Once the pilot flame is present,

the ICB monitors the flame sense circuit for pilot flame stability.

If the pilot flame is unstable or lost completely, then the ICB will

immediately close both the pilot and main gas valves. The ICB

will retry the purging and ignition sequence. If the flame is

unstable or lost more than 16 times during the same call for

heat, then the ICB will lock out furnace operation for 5 minutes.

Flash Codes

The UCB will initiate a flash code associated with errors within

the system. Refer to UNIT CONTROL BOARD FLASH CODES

Table 25.

Resets

Remove the call for heating by lowering the thermostat setting

lower than the conditioned space temperature. This resets any

flash codes.

Heat Anticipator Setpoints

It is important that the anticipator setpoint be correct. Too high

of a setting will result in longer heat cycles and a greater

temperature swing in the conditioned space. Reducing the

value below the correct setpoint will give shorter “ON” cycles

and may result in the lowering of the temperature within the

conditioned space.

Table 21: Single Stage Gas Heat Limit Control Setting

Unit

(Tons)

Capacity, MBH Limit Control Opens, °F

Input Output Direct Drive Belt Drive

3 50 40 240 240

3 100 80 170 210

4 75 60 210 240

4 125 100 165 210

5 100 80 170 210

5 125 100 165 210

Table 22: 2 Stage Gas Heat Limit Control Setting

Unit

(Tons)

1st Stage

Capacity

2nd Stage

Capacity

Limit Control Opens,

°F

Input

(MBH)

Output

(MBH)

Input

(MBH)

Output

(MBH)

Direct

Drive

Belt

Drive

3 45 36 75 61 210 240

3 69 55 115 92 200 200

4 45 36 75 61 210 240

4 75 60 125 101 165 210

5 45 36 75 61 210 210

5 75 60 125 101 165 210

Table 23: Gas Heat Anticipator Setpoints

Gas Valve Anticipator Setpoints

Honeywell VR8204M 0.60 amp

White-Rogers 36E36 0.54 amp

1 2 ... 41 42 43 44 45 46 47 48 49 50 51 ... 57 58

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York W)036 THRU 060 Specifications Page 46

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