Installation Guide
16
11-HD14D1-9-EN
7. Advanced Operation
7.1 Control response rate
Allows the user to select a set of higher proportional-
integral control constants to increase the responsiveness
of the Control. Selecting “Fast” will cause the Control to
generate load value at a faster rate. Control Response rate
can be adjusted in Installer Setup>Comfort Settings.
7.2 Dehumidification
The 850 utilizes the following methods for dehumidification:
•
Air flow reduction (applies only to variable speed
blowers) – The 850 can reduce the system air flow
by 30% anytime the indoor RH is higher than the
cooling RH target. Air flow reduction is disallowed if
the indoor temperature is more than 2°F above the
cooling setpoint. Dehumidification is factory enabled
in the Installer Setup>Comfort Settings.
All “Fan Off” delays are also defeated when
dehumidification is enabled and the indoor RH
exceeds the cooling RH target.
•
Overcooling (applies to variable speed and non-
variable speed blowers) - If overcooling is enabled,
the Control will allow a 0.1°F of overcooling for each
1% of RH error. A maximum amount of overcooling
can be configured for 1°, 2° or 3°F.
EXAMPLE OF OVERCOOLING
WITH MAXIMUM CONFIGURED AT 2
°
TARGET
HUMIDITY
ACTUAL
HUMIDITY
PERCENT
OF RH
ERROR
DEGREES OF
OVERSHOOT
40%
45%
5%
0.5
° Overshoot
40%
55%
15%
1.5
° Overshoot
40%
65%
25%
2.0
° Overshoot
40%
70%
30%
2.0
° Overshoot
When the system is actively overcooling,
Dehumidification will be displayed on the 850 home
screen. The maximum amount of overcooling is
configured in Installer Setup>Comfort settings.
•
Smart Continuous Fan (applies to variable speed and
non-variable speed blowers) – If enabled, continuous
fan operation will be interrupted when indoor RH
exceeds desired cooling RH target. A humidity icon
will be displayed along with the fan icon to indicate
that continuous fan operation has been disabled due
to high humidity conditions. Smart Continuous Fan
will also interrupt the fan circulate mode when indoor
humidity exceeds the desired cooling RH. This feature
can be enabled in the Installer Settings>Comfort
Settings>Smart Continuous Fan settings.
7.3 Dehumidifier Operation
The 850 has the ability to control a Whole-House
Dehumidifier through the normally open dry AUX Contacts
on the optional Relay Paned. Control options are:
•
Stand Alone Operation – Dehumidifier can operate
independent from cooling operation as long as the
850 Control is in Cooling mode or Auto mode and the
last call was cooling.
If Stand Alone Operation is selected, the 850 Control
allows the user to select whether the indoor fan
operates with dehumidifier request.
•
With Active Call for Cooling Only – Dehumidifier can
only operate during an active call for cooling.
All dehumidifier control options are located in the
Installer Setup>Accessories Settings.
7.4 Dual Fuel Operation
The 850 can control a dual fuel system without the need of
an external dual fuel kit. An Outdoor Temperature Sensor
must be installed and enabled for Restricted Modes to be
available. The 850 Control options are:
•
Non Restricted Mode – The Control will determine
which mode of heat will operate to maintain comfort
based on the calculated system load value. With a load
value in compressor heating range the heat pump will
operate and if the load value climbs to auxiliary heat
range, the heat pump will cycle off and the auxiliary
heat source will cycle on. Once the load value falls
below the auxiliary heat range, the auxiliary heat will
cycle off, and the heat pump will cycle back on.
•
Restricted Mode (compressor heat only) – Once
enabled an outdoor temperature lockout can be set
to disable compressor heating operation. When the
outdoor temperature falls below the compressor
heat lockout the system will operate on auxiliary
heat source only. At any temperature above the
compressor heat lockout the system will operate
the same as non-restricted mode, heat pump or
auxiliary heat would be allowed based on system
load value. Once the compressor heat is locked out,
the outdoor temperature must rise at least 4° above
the compressor heat lockout setting before allowing
compressor heat again.
