Honeywell DT92 Manual page 14

INSTALLER MODE – APPLICATIONS SETTINGS
The DT92 has a special Installer Mode where some features can be adjusted to suit the application and the needs or
lifestyle of the user. Each adjustable feature is called a Parameter. These are described below.
Parameter
Minimum ON/OFF time
Cycle rate
Proportional band width
Temperature
measurement offset
Upper / Lower
temperature limits
Energy saving ECO
temperature
Heating or Cooling
operation
Off/standby setpoint
Room temperature
sensor use
Failsafe operation mode
HR80 window open
function enabling
HR80 local override
function enabling
Reset parameters
DT92 is able to set a minimum limit for the on and off times of the controlled device or
appliance, to prevent damage or excessive wear. This minimum time can be set to 1,
2, 3, 4, or 5 minutes, and is particularly important for heating applications with oil
boilers, or air conditioning applications with compressors. Recommended settings are
shown in the next table.
Within the control proportional band, the output will be cycled several times per hour,
to give precise temperature control. This can be set to 3, 6, 9, or 12 cycles,
depending on the application. Recommended settings are shown in the next table.
The proportional band is the temperature band, adjacent to the set temperature point,
within which the thermostat will cycle the controlled output (to control the boiler, for
example). Above or below this band the output will either be fully on or fully off.
The band can be adjusted up to 3°C (default 1.5°C) to provide improved temperature
control. This is useful for (a) well-insulated homes with over-sized heating systems or
(b) air systems with a fast response
If the thermostat is located in a particularly hot/cold location and cannot be moved,
then the measured/displayed temperature can be adjusted by +/- 3°C. This is useful if
the homeowner wants the reading to match the temperature display on another
appliance.
The normal upper temperature limit of 35°C can be reduced as low as 21°C to save
energy. The normal lower limit of 5°C can be raised as high as 21°C to protect
inhabitants from the cold.
On the DT92E ECO model, pressing the ECO button immediately puts the thermostat
into energy saving mode, where it will control at this predefined temperature for as
long as the user wishes. This temperature can be set from 5°C to 35°C.
DT92 can be used for heating or cooling applications. If heating/cooling changeover is
selected, the thermostat can be manually switched from heating to cooling (and back
again) by pressing and holding the ▲ and ▼ buttons together for 3 seconds, in
normal operating mode.
When the off/standby button is activated, the DT92 will control to a special off/standby
setpoint. By default this is set to 5°C to provide frost protection, but it can be set up to
16°C if required. It can also be set off, by setting the parameter value to -- to provide
a positive off function. In cooling mode the default setting is off.
In normal operation the DT92 uses it own temperature sensor. If it is operating in a
wireless system with HR80 programmable radiator valves the DT92 needs to know
that it is controlling HR80s. In addition, there is a choice of whether the HR80s can
use their own in-built temperature sensors, or whether they will use the temperature
sensed by DT92. The 3 choices then become:
a) DT92 operating without HR80
b) DT92 operating with HR80, HR80 using their own temperature sensor
c) DT92 operating with HR80, HR80 using the temperature sensed by DT92
Should RF communications be interrupted for a significant period of time, for
whatever reason, it is possible to specify the desired mode of operation under these
circumstances. The choices are for the Relay box to switch off, or for it to operate at
20% on.
In a system where DT92 is operating with HR80 programmable radiator valves, the
HR80 is capable of detecting whether a window has been opened. This parameter
enables the HR80 response to this condition – it can either shutdown (enabled) or
operate as before (disabled)
In a system where DT92 is operating with HR80 programmable radiator valves, the
user can override the room temperature setpoint using the HR80. This parameter can
allow (enable) this operation, or prevent it (disable).
This provides a means of resetting all the parameters to the factory supplied values.
DT92 WIRELESS DIGITAL ROOM THERMOSTAT
Description and typical use
14