Electrical Auxiliary Heat; Gas Auxiliary Heat; Auxiliary Heat Via Hot Water Coil - Johnson Controls York YKN2Open board Technical Information

4 Operation
4.5 Switching of the accessories

4.5.3 Electrical auxiliary heat

The program can control up to four electrical heating stages.
The stages are started up in accordance with indications from the demand control unit.
Whenever the electrical heating is in operation, the indoor fan will always be in operation.

4.5.4 Gas auxiliary heat

The program can control up to four gas stages.
• They are started up in accordance with indications from the demand control unit.
• The second stage cannot be started up if the first is not in operation.
• This also applies to the third and fourth stages.
• Control of the gas stage is carried out with 1 or 2 accessories, depending on whether it is necessary
to control 2 or 4 gas stages.
• Units with only two gas stages can have one or two burner controls. If it is necessary for the accessory
to be able to activate 2 controls, this is indicated by a jumper put on the J1.
• Whenever the gas heating is in operation, the indoor fan will always be in operation.
Alarms:
• A fault in alarm 1 causes the entire gas heating to stop.
• A fault in alarm 2 would stop the second and fourth stages (if they exist).
• If a fault is produced during the start-up of a burner, the reset signal is activated for 1 second causing
the alarm to reset. The number of alarm resets on start-up is limited to 5 times.
• From here, the control system generates an alarm in the thermostat display or the YKN2Open board,
blocking the gas stages.
• The demand does not deactivate until the thermostat stops requesting heat.
In gas heat pump units:
• If the outside temperature is higher than 5 °C and there is a demand for heat, the compressors operate
if available.
– If the compressors are not available, the gas auxiliary heat operates.
• If the outside temperature is lower than 5 °C and there is a demand for heat, the gas auxiliary heat
operates if available.
– If the gas auxiliary heat is not available, the compressors operate.

4.5.5 Auxiliary heat via hot water coil

N O T E
[See the operating parameters in the section Rooms, see on page 25].
Its function is to generate heat and it can control up to four hot water coil stages, which start up in
accordance with indications from the demand control unit. They are limited by the supply temperature
(30, 40, 45 and 50 °C).
If the conditions are favourable, the valve is modulated in accordance with the supply probe, whereby
the objective is to achieve the maximum supply temperature without exceeding 50 °C
(BACTPIMP_MAX).
• Favourable conditions are deemed when the water temperature is above 30 °C (BACTPH2O_MIN)
5 minutes (BACTIH2O_MIN) after opening the valve.
• Once the system is operating, a check is constantly made to ensure the conditions remain favourable.
• If the conditions are favourable, the yellow LED lights up permanently as an indication.
In the event that non-favourable conditions have been detected, and demand exists, 20 minutes are
timed (BACTIRTR) and the conditions are checked again after this time.
Whenever the water heating is in operation, the indoor fan will always be in operation.
Whenever the hot water coil heating is running (circulation pump running and temperature favourable),
the indoor fan will also be operating.
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