Installer Setup Flowchart; Opentherm Setup And Information Display - Honeywell Y9520Z Sundial RF2 Pack 5 Installation Instructions Manual

4.4 Installer Setup Flowchart

4.5 OpenTherm® Setup and Information Display
ST9520C has the facility for a direct low voltage communications connection to the boiler using the OpenTherm® protocol. If the boiler supports it,
OpenTherm allows the boiler's gas valve to be controlled so the amount of heat provided exactly matches the varying demand. By reducing the flow
temperature to a minimum as it leaves the boiler, the return temperature is kept below the dew point (55°C) whenever possible, thus allowing the boiler
to operate in its most efficient condensing mode.
The OpenTherm control can be adjusted by setting some parameters in OpenTherm Setup mode. In addition, as OpenTherm is a communications
protocol, it is possible to view some operating metrics in this mode, such as supply water temperature, pressure, and flame modulation level. These
are shown in the table below.
OpenTherm PARAMETER Parameter
Enable or Disable
OpenTherm
Supply water temperature
Water pressure
Flame modulation %
Central Heating Output
Temperature Limit
Enable or Disable
OpenTherm Low Load Mode
Reset OpenTherm
parameters to defaults
* this value may be further limited by the boiler
** the boiler may not allow low load operation
Note: When OpenTherm is enabled, BOILER binding is not possible and anything already bound in the BOILER binding slot is deleted (see page 16).
Refer to Honeywell Technical Help Desk for wireless OpenTherm possibilities using the R8810A OpenTherm receiver.
LoT™ Display Default
ID Description Value
Ot OpenTherm 0
SUPPLY °C ----
PRESSURE ----
MODULATION ----
CL CH LIMIT 90
LL LOW LOAD 1
rS OT RESET 1
LoT™ Display
Parameter
Number
Range of Description [LoT™ Display Description]
Values
0, 1 0 = disabled
1 = enabled
0 – 99 Supply water temperature
0.0 - 4.0 Water pressure
0 – 100 Flame modulation %
40 – 90 * Central heating water temperature limit [SET CH LIMIT]
0, 1 ** 0 = disabled
1 = enabled
0, 1 0 = do not reset
1 = default parameters
11
or
Parameter
Value
[DISABLED]
[ENABLED]
[SUPPLY °C]
[PRESSURE]
[MODULATION]
[DISABLED]
[ENABLED]
[NO RESET]
[RESET]