Heat Anticipator Setpoints; Gas Heating Sequence Of Operation; Gas Heat Operation Errors; Limit Control Setting - York DM036 Installation Manual

Table 23: Limit Control Setting
VOLTAGE kW
7
10
15
380/415-3-50
20
30
Flash Codes or Error Messages
The UCB will initiate a flash code associated with errors within
the system. Refer to flash code on the Simplicity Lite Control
(See Table 28) or sent error message to the LCD Simplicity SE
Control.
Reset
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. Refer to Table 24 for the required heat
anticipator setting.
Table 24: Electric Heat Anticipator Setpoints
HEATER
VOLTAGE
KW
7
10
15 380/415-3-50
20
30

Gas Heating Sequence Of Operation

When there is a W1 call for heat, the heat relay (RW1) is
energized by the unit control board (UCB). The RW1-1 contacts
immediately close energizing the ignition control board (ICB).
The ICB checks the state of the flame sense circuit, the roll out
switch, the centrifugal switch and the primary / auxiliary
temperature limit switch circuit. If they are in the expected state,
then the ICB energizes the draft motor and verifies that the
centrifugal switch located on the end of the draft motor closes.
After the centrifugal switch closes, a 15 second heat exchanger
purging period is completed. After this purging period, the ICB
will simultaneously energize the pilot gas valve and the ignition
Johnson Controls Unitary Products
TEMPERTURE Open Temp
LIMIT SWITCH ºC[ºF]
2, 4, 6 58[140]
2, 4, 6 58[140]
2, 4, 6 58[140]
3 71[160]
3 65[150]
SETTING, AMPS
TH1 TH2
0.35 -
0.35 -
0.35 -
0.37 0.29
0.37 0.29
coil. Once the flame sensor senses a pilot flame is present, the
ignition coil is de-energized. The ICB checks for pilot flame
stability and once the ICB is satisfied that the pilot flame is
stable, the main gas valve is energized by the ICB. The UCB
will energize the indoor blower after a 45 second delay from the
call for heat. The ICB and UCB both monitor the furnace safety
devices during the furnace operation. When the call for heat is
satisfied, the ICB closes the pilot and main gas valves and
performs a 30 second purging of the heat exchanger by
continuing the operation of the draft motor. The UCB continues
the operation of the indoor blower for a configurable amount of
time after the call for heat is satisfied.
REDUNDANT
VALVE
GAS MAIN
GAS
VALVE
TO PILOT BURNER
Figure 20: Gas Valve Piping
Two Stage Furnace Only
If a W1 only call for heat from a two stage thermostat is present,
then a two stage furnace will start on high fire for 1 minute and
then reduce to low fire until the call for heat is satisfied or a W2
call for heat is received. If a W2 call for heat is received while in
low fire operation, then the ICB will immediately move to high
fire operation. If a W1 and W2 call for heat is present, then the
furnace will remain on high fire operation until the W2 call for
heat is satisfied.
Automatic staging of a two stage furnace using a single stage
thermostat is possible. To achieve automatic staging of a two
stage furnace using a single stage thermostat, a jumper is
installed between R and W2 on the UCB with the single stage
thermostat heat control connected to W1. Wired in this manner,
the ICB will interpret the continuous power on W2 as automatic
two stage operation of the two stage furnace. The unit will
operate the same as a W1 only call for heat for 10 minutes. If
the call for heat is not satisfied in the 10 minutes, then the ICB
will move to high fire operation until the W1 call for heat has
been satisfied.

Gas Heat Operation Errors

During furnace operation, the ICB monitors the flame sense
circuit, the centrifugal switch, the primary limit switch and the
roll out switch. If a signal from any of the inputs moves to a fault
state, then the ICB immediately closes the pilot and main gas
valves. The ICB will determine the device that is signaling a
fault and flash a code for that device. A primary limit trip,
centrifugal switch trip or flame sense fault triggers a temporary
lock out. An auxiliary limit or a roll out switch trip requires
intervention to reset the ICB. The UCB also monitors the
primary limit and gas valve.
5011492-XIM-B-0815
MAIN VALVE
TO MAIN
BURNER
39