Table of Contents
Advertisement
Mixing Device Type - ------ -- ---- ---- - --- -- - -- - -- - - -- -- - -- --- -- --- --- - - --- --- - - --- --- - - --- - --- - -- - -- - --
- ----- ----- ----- ---- --- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - -
The House Control can operate a mixing device such as
a mixing valve or variable speed injection pump based
upon one of four output signals. The device output bar
graph on the display indicates the approximate position
of the mixing device.
Variable Speed Injection Pump
A standard wet rotor circulator can be connected to the
Variable Speed Pump output on the back of the control.
The control varies the circulator speed to maintain the
correct mixed supply water temperature at the mix supply
sensor. For correct sizing and piping of the variable speed
injection circulator, refer to essay E 021. Note: Pumps
manufactured with an internal variable speed controller
are not compatible with the House Control.
Floating Action 24 V (ac)
A 24 V (ac) floating action actuator motor and mixing valve
can be connected to the Floating Action outputs on the
front of the House Control. The control pulses the actuator
motor open or closed to maintain the correct supply water
temperature at the mix supply sensor when there is a
requirement for mixing.
Boiler Temperature Reset Operation
Boiler Expansion Call -- - ---- ----- - ---- -- -- -- - - -- - -- - - -- - -- -- - --- -- -- - --- -- - -- --- -- - -- --- -- - - - -- - -- - --
When a device connected to the tN4 Boil Expansion
terminals calls for heat, the House Control registers a Boil
Expansion call for hydronic heating on the boiler loop.
Boiler Target --- - -- -- --- - ----- -- -- -- - - --- -- - -- - -- -- --- --- -- - -- --- -- --- --- - - --- --- - - --- --- - - -- -- - -- - -- -
--- -- -- -- -- ---- ----- ---- ----- - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
When there are no Boiler Expansion or Mix calls, the boiler
target in the View menu on the display will show '– – –' to
indicate there is no requirement for boiler operation.
Once a Boiler Expansion Call is present, a boiler target
is determined by the control using the boiler heating
curve (boiler minimum, boiler design and outdoor design
settings) together with indoor temperature feedback from
the thermostats. The heating curve operates based on the
principle that a buildings heat loss increases with colder
outdoor temperatures. The calculated Boiler Target will be
shown in the View menu on the display.
When a Mix or Mix Expansion Call is present, the control
calculates a boiler target that is higher than the mix target
using Boiler Load Reset.
Boiler Minimum
The House Control protects non-condensing boilers from
sustained flue gas condensation and thermal shock through
the Boiler Minimum setting. The boiler minimum is the
lowest temperature that the control is allowed to use as a
boiler target temperature. If the boiler is operating at the
boiler minimum temperature, the "MIN" segment is turned
on in the display when viewing either the boiler supply
temperature or the boiler target temperature.
© 2011
D 403 - 07/11
---- ----- ---- ----- --- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - -
Modulating 0-10 V (dc)
*Only available if a one or two stage on-off boiler is
used.
A modulating 0-10 V (dc) actuating motor can be used to
operate the mixing valve. The control uses the Mod dc/mA
output to provide an analog 0-10 V (dc) signal to the actuator
in order to maintain the correct mix supply temperature.
Modulating 4-20 mA
*Only available if a one or two stage on-off boiler is
used.
A modulating 4-20 mA actuating motor can be used to
operate the mixing valve. The control uses the Mod dc/mA
output to provide an analog 4-20 mA signal to the actuator
in order to maintain the correct mix supply temperature.
Mixing Device Exercising
The control operates the mixing device from 0 to 100% output
every 3 days to help prevent corrosion and / or precipitate
build up on the mixing valve or pump that could lead to
seizure of the mixing device. The control ensures that no
heat is supplied to the zones during exercising.
Boiler Heating Curve
Decreasing Outdoor Temperatures
Boiler Maximum
The control has a fixed boiler maximum temperature of +
10°F (+5.5°C) higher than the Boiler Design setting for the
Boiler Heating Curve. When this occurs, the "MAX" segment
will display when viewing the boiler target or boiler supply
temperature in the view menu. The control will operate
the boiler so that the boiler supply temperature will never
exceed 210°F (99.0°C).
22 of 32
Section C
Calls
Boil Exp
(Outdoor Design,
Boiler Design)
(70°F Outdoor,
Boiler Minimum)
Advertisement
Table of Contents
