Heating System; Safety Controls (Heating); Heat Anticipator Setpoints; Pre-Start Check List - York SUNLINE PLUS D1EG090 Installation Instruction

530.22-N4Y

HEATING SYSTEM

The following sequence describes the operation of the gas heat
section.
CONTINUOUS BLOWER: With the room thermostat switch set
to "ON", the supply air blower will operate continuously. The
normally closed contact "K5-1" provides 24 volt power to the
"3M" relay. The "3M-1" and "3M-2" power contacts close and
the blower motor operates.
INTERMITTENT BLOWER: With the room thermostat system
switch set to the "AUTO" or "HEAT" position and the fan switch
set to "AUTO", the supply air blower will operate after the room
thermostat calls for heat and the time delay relay closes.
The "TH1" closes, the draft motor relay "DMR" is energized.
The "DMR" power contact closes which energizes the line
voltage draft motor. As the speed of the draft motor reaches
approximately 2500 RPM, the centrifugal switch contact
located on the end of the draft motor shaft closes to power the
ignition control "IC".
After 15 seconds, the "IC" will start the ignitor sparking and will
open the redundant valve located inside the main gas valve
"GV" to allow a flow of gas to only the carryover tube. See
Figure 11. Only after the pilot flame has been ignited and the
presence of pilot flame detected at the "IC" by a signal sent
back through the flame sensor is sparking terminated and the
main gas valve opened.
Gas flows into each of the main burners and is ignited from the
carryover tube flame.
If "IC" fails to detect a pilot flame, it will continue to try for a
maximum of 85 seconds to ignite the pilot tube. If the pilot flame
is not detected, then "IC" will soft lock out for 5 minutes. If the
pilot flame is not detected after 16 retries, then "IC" will hard
lock out the first stage furnace operation until 24V power is
removed from the module either at the unit or by resetting the
room thermostat.
At the same time power was supplied to the "DMR", a parallel
circuit activates "TDR" which closes "TDR" after approximately
16 seconds and energizes "K5" which closes "K5-2" and starts
the blower by energizing "3M".
When "TH2" closes calling for second stage heating, it
energizes "W2" on the gas valve "GV" directly.
When the heating cycle is complete, "TH-1" opens
de-energizing the "DMR" and "IC", thus closing the redundant
and main gas valves. The blower motor continues to run
(approximately 15 seconds after the furnace is shut down) until
"TDR" opens de-energizing the "K5" and "3M" relays.
REDUNDANT
VALVE
GAS MAIN
GAS
VALVE
TO PILOT BURNER
FIG. 11 - GAS VALVE PIPING
12
SAFETY CONTROLS
The control circuit includes the following safety controls:
1. Limit Control (LS). This control is located inside the heat
exchanger compartment and is set to open at the
temperature indicated in Table 9. It resets automatically.
The limit switch operates when a high temperature
condition, caused by inadequate supply air flow occurs,
thus shutting down the ignition control and closing the main
gas valve and energizing the blower.
2. Centrifugal Switch (CS). If the draft motor should fail, the
centrifugal switch attached to the shaft of the motor
prevents the ignition control and gas valve from being
energized.
3. Redundant Gas Valve. This valve is an integral part of the
main gas valve and is located up stream of the main gas
valve. Should the main gas valve fail in the open position
the redundant valve serves as a back up and shuts off the
flow of gas.
4. Flame Sensor Rod. This sensor rod is located on the far
side of the carryover tube. If the ignition control does not
receive a signal from the flame sensor indicating that the
pilot flame has ignited properly, the main gas valve will not
open. If the flame sensor fails to detect the pilot flame during
operation of the main burners, a signal is sent to the ignition
control to close the main gas valve.
5. Rollout Switch. This switch is located in the burner
vestibule. In the event of a sustained main burner flame
rollout, it shuts off the ignition control and closes the main
gas valve.
TABLE 9 - LIMIT CONTROL SETTING
Units
(Tons)
7-1/2
7-1/2
10 & 12-1/2
10 & 12-1/2

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 temperture within the
conditioned space.
Gas Valve
Honeywell
VR8520
MAIN VALVE
White-Rodgers
36C76

PRE-START CHECK LIST

Complete the following checks before starting the unit.
TO MAIN
1. Check the type of gas being supplied. Be sure that it is the
BURNER
same as listed on the unit nameplate.
2. Make sure that the vent and combustion air hoods have
been properly installed.
Capacity, MBH
Input Output
163 130
204 163
204 163
245 198
Anticipator Setpoint
1st Stage 2nd Stage
0.50 amp 0.24 amp
0.60 amp 0.10 amp
Unitary Products Group
Limit Control
Opens, °F
180
170
170
170