Main Features - Honeywell DT92 Manual

MAIN FEATURES

Extra-Large Display
The DT92 has a large display, ensuring it is easy to
read and allowing essential information to be displayed,
when required. The large characters and high contrast
screen are especially important for those with impaired
vision.
Simple Interface
The user interface has been made as simple as
possible to make DT92 very easy to use. Buttons have
been labeled ▲ and ▼ to identify them as the means
of increasing and decreasing (respectively) the setpoint
temperature. The display normally shows the actual
room temperature. When one of the buttons is first
pressed, the setpoint temperature is shown flashing,
accompanied by the ▲ and ▼ symbols. Further
buttons presses will increase or decrease the setpoint
in increments of 0.5°C.
Off/Standby Button, with Frost Protection
The off/standby button allows DT92 to switch off the
heating (or cooling) system at the touch of a button. To
prevent accidental switch-off, the button must be held
for 2 seconds to activate the change. When off, DT92
will maintain control at a frost protection setpoint,
factory set to 5°C but adjustable between 5 and 16°C.
If required, frost protection can be switched off, to
provide a positive off function. These adjustments are
made by entering the DT92 Installer Mode.
Installer Mode
The Installer Mode is where DT92 can be configured
for different applications, and customized to meet the
needs of the user. The operating properties that can be
adjusted are called parameters, and these are
described in detail on page 6.
Parameters are as follows:
•
Minimum on/off time
•
Cycle rate
•
Proportional band width
•
Temperature measurement offset
•
Upper setpoint limit
•
Lower setpoint limit
•
Energy saving ECO temperature (on DT92E only)
•
Selection of heat/cool changeover operation
•
Off/Standby setpoint
•
Room temperature sensor use (when used with
HR80 intelligent radiator valves
•
Failsafe operation mode (if RF comms are lost)
•
HR80 window open function enabling
•
HR80 local override function enabling
•
Reset all parameters to factory settings
Installer Mode is entered via a sequence of button
presses. The buttons are also used to scroll between
parameters and to make changes to their values.
DT92 WIRELESS DIGITAL ROOM THERMOSTAT
2-Way RF Communications
RF communications between the room thermostat and
the relay box is 2-way, making it more efficient and
reliable, and allowing the room thermostat to display
information from the relay box, such as actual relay
status or communications loss.
Signal Strength Test Mode
Another benefit of 2-way RF is to allow the room
thermostat to display the strength of the signal that the
relay box is receiving. This ensures the thermostat can
be positioned in the best possible location for system
performance.
Reliable RF Communications in 868MHz band
868MHz is a well regulated band where continuously
transmitting devices are not permitted. Together with a
1% transmission duty cycle, this means the possibility
of interference or clashing messages is minimized, and
increases the reliability of communications.
NVRAM Storage of Settings
All parameter settings are stored in a special kind of
memory called NVRAM so they will be retained
indefinitely even if the batteries are removed.
Advanced Self-learning TPI Control
DT92 uses a self-learning 'fuzzy logic' time-proportional
control algorithm. This form of control is better than
conventional PI control as it has a faster response and
better performance in steady state conditions. It
performs equally well in a wide range of different
installations, and ensures energy savings by controlling
closer to setpoint and minimising temperature
overshoots.
Additional Energy saving ECO feature
In a heating system, one of the best ways to save
energy is to reduce the setpoint temperature. The DT92
green ECO button provides a simple and convenient
way of doing this for a period of time of the user's
choice. The ECO energy saving setpoint is pre-defined
in the Installer Mode. The factory setting is 18°C, but it
can be adjusted (between 5°C and 35°C) to give a
timed boost, if required. When the ECO button is
pressed, the user is given the chance to set the time
required at this new temperature, from 1 hour to 24
hours in 1 hour increments. The display indicates that
ECO mode has been set, and will count down the time
remaining in energy saving mode. Should they wish to
readjust the temperature setting, they can do that too,
using the ▲ and ▼ buttons.
ECO mode is cancelled simply by pressing the ECO
button again.
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