Technical information

33
16.5.- Heating operation sequence with gas
(models D4IG)
REQUEST FOR HEAT, 1: If the thermostat generates a de-
mand for heat, the YKlon board activates the indoor fan and
the gas control board (A6) generates a W1 output (terminal
41). If thermostat LS1 (manual reset) is closed and gas supply
pressure is over the set point of the gas pressure switch (GS),
start-up control (IC1) is activated and start-up begins.
See Fig. 16 for a typical layout of the gas valves.
START-UP SEQUENCE: The start-up control check to see
that the Air Pressure Switch contact (AS1) is open. If it is,
the burner fan motor is activated and a 30 second prepurge
sequence is begun.
As long as contact AS1 closes and thermostats RS11, RS12
(manual reset) and LS11 (automatic reset) are also closed
and the prepurge has ended, the start-up transformer is
activated, and this generates a high frequency arch at the
firing electrode. The main electrovalves and the 1st stage gas
electrovalve are activated at a reduced flow, and the burner
assembly ignites.
Gas valve layout
vated. If not, the start-up control is locked out and generates
an alarm to the gas board, which resets IC1. The gas board
can carry out a maximum of 5 resets while the thermostat
generates the same demand for heat. Then the gas control
is locked out and thermostat DPC-1 will display the failure.
If the start-up sequence is correct but the flame goes out
shortly after, the start-up the IC1 control is locked out and
generates an alarm. If thermal switch LS11 or burner assem-
bly switches RS11, RS12 were to open due to high tempera-
ture in the gas control compartment, or if air pressure switch
(AS1) were to open due to a failure in the combustion air (for
example, lock out or failure of the fan), the unit is locked out
and an alarm is generated.
REQUEST FOR HEAT 2: If the thermostat generates a sec-
ond demand, the gas control board (A7) generates a W2
output (terminals 44, 45), allowing the gas system to operate
and 50% its capacity.
REQUEST FOR HEAT 3: If the thermostat generates a third
demand, the gas control board (A6) generates a W3 output
(terminals 42, 43), allowing the gas system to operate at
75% of its capacity. The smoke discharge motor relay M8
is activated.
REQUEST FOR HEAT 4: If the thermostat generates a fourth
demand, the gas control board (A7) generates a W4 output
(terminals 46, 47), allowing the gas system to operate at
100% of its capacity. Relay KGV2 is activated, switching to
high speed of the smoke discharge motor M9.
16.6.- Heat operation sequence with electric
heaters (models D4IC)
REQUEST FOR HEAT, 1: If the thermostat generates a
demand for heat, the YKlon board activates the indoor fan
and the output of auxiliary heater 1 or 2, depending upon the
number of operating hours in use.
REQUEST FOR HEAT, 2: If the thermostat generates a sec-
ond demand, the output of auxiliary heater 1 or 2 is activated,
depending upon the number of operating hours in use.
16.7.- Heat operation sequence with heat pump
(models B4IH) with electric heaters (optional)
REQUEST FOR HEAT, 1: If the thermostat generates a de-
mand for heat, the YKlon board activates the indoor fan and
the compressor with less operating hours, or available.
REQUEST FOR HEAT, 2: If the thermostat generates a second
demand, the second compressor becomes operative.
REQUEST FOR HEAT, 3: If the thermostat generates a third
demand, the third compressor becomes operative.
REQUEST FOR HEAT, 4: If the thermostat generates a fourth
demand, the output of auxiliary heater 1 or 2 is activated,
depending upon the number of operating hours in use.
REQUEST FOR HEAT, 5: If the thermostat generates a fifth
demand, the output of auxiliary heater 1 or 2 is activated,
depending upon the number of operating hours in use.
EMERGENCY HEAT: If the Emergency Heat mode is selected
on the thermostat, the compressors are turned off. The first
demand for heat starts one stage of the heater, and the
second, the other stage.
16.8.- Defrost sequence (models B4IH)
The heat pumps are equipped with a defrost adjustable timer
If the flame detector (ionizing electrode type) generates suf-
ficient intensity in a 5-second interval, the gas valve is acti-
- Fig. 16 -
MAIN ELECTROVALVE
AND REGULATOR
TWO-STAGE
REGULATING
ELECTROVALVE
TO BURNER
MANIFOLD
GAS
SUPPLY
FILTER
GAS PRESSURE SWITCH