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Rev 2.0
63-7048 1998 Honeywell Inc.
Page 12 of 22
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Furnace Cycles
Humidifier Cycles
Outdoor Temp.
Dewpoint
Window Temp.
Temp. Setpoint
Room Temp.
Time (hrs)
Temperature (
o
F)
Digitial Output
Figure 8 – Software Simulation of H1008 Automatic Humidity Control Algorithm
The simulation is performed by constructing a house model with a given volume, wall
and window heat loss factors, infiltration rates, and internally generated humidity. The
house is then subjected to varying weather conditions and temperature setpoint profiles.
The result is shown above; a pattern of furnace and humidifier cycling is established in
response to the input conditions.
As seen in Figure 8, the H1008 algorithm performs quite well. During the night setback
periods, when it is very cold outside, the humidifier cycles less frequently than it does
during the afternoon hours. During the entire period the dewpoint tracks just below the
window temperature, maintaining moisture free windows.