User Manual

Sequence of Operation
Gas Furnace (Optional)
13
Siemens Industry, Inc.
Application Note, App 14901
140-1230
2020-02-11
● If HTG STG4 is an electric heater:
If IndoorTmpEff is less than the switching on point of the fourth heating stage
(HeatSp – 1/2 HeatingDB – StgDifHt*3), HTG STG4 has been OFF for at least
the time set in MIN OFF, and the Inter-stage Delay timer has expired, HTG STG4
is turned ON.
If IndoorTmpEff is greater than the switching off point of the fourth heating stage
(HeatSp + 1/2 HeatingDB – StgDifHt*3), and HTG STG4 has been ON for at least
the time set in MIN ON, HTG STG4 is turned OFF.
Gas Furnace (Optional)
In a dual-fuel heat pump where the compressors and furnace work exclusively, see the
Ambient HP Lockouts section for further information on how to configure.
The furnace is controlled as follows when it is set to run by HP Lockout:
If at least one stage of gas heater is being used (AUX HTG STG > 0, and FAN MODE
= gAS):
● If IndoorTmpEff is less than the switching on point of the first heating stage
(HeatingSp – 1/2 HeatingDB), and Aux Heater1 has been OFF for at least the
time set in MIN OFF, Aux Heater 1 is turned ON.
● If IndoorTmpEff is greater than the switching off point of the first heating stage
(HeatingSp + 1/2 HeatingDB), and Aux Heater1 has been ON for at least the time
set in MIN ON, Aux Heater1 is turned OFF.
If AUX HTG STG NUMBER = 2, the application controls Aux Heater2 as follows:
● If IndoorTmpEff is less than the switching on point of the second heating stage
(HeatingSp – 1/2 HeatingDB - StgDifHt), Aux Heater2 has been OFF for at least
the time set in MIN OFF, and the Inter-stage Delay timer has expired, Aux Heater2
is turned ON.
● If IndoorTmpEff is greater than the switching off point of the second heating stage
(HeatingSp + 1/2 HeatingDB - StgDifHt), and Aux Heater2 has been ON for at
least the time set in MIN ON, Aux Heater2 is turned OFF.