© 2011
D 406 - 12/11
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Heat Pump Operation
Section E
Number of Heat Pump Stages
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The House Control 406 is capable of operating a single heat
pump, either one or two stage. Use the HP TYPE setting in
the Adjust Menu to select whether a second stage is available
(1STG, 2STG).
Equal Run Time Rotation
If the system has two heat pumps that require equal run time,
set the HP TYPE setting to ROT (Rotate). This way the two
heat pumps will rotate their starting order when one heat pump
accumulates 48 hours more run time than the other.
Heat Pump Source
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The House Control 406 only supports heat pump systems
where the load side is hydronic, or water based. The source
side however can either be air source or water source. Use the
HP SOURCE setting in the Adjust Menu to select if the heat
pump is air-to-water (AIR) or water-to-water (GEO).
Staging
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When two heat pumps or a two-stage heat pump is being
used (HP TYPE = 2STG or ROT), the staging method of the
406 changes depending on the HPSOURCE setting: AIR or
GEO.
With an air source heat pump selected, the 406 will stage on
sequentially and off sequentially. This allows the supply water
temperature to be kept close to the target.
AIR Source Staging
Stage 2 ON (Y2)
Stage 1 ON (Y1)
O/B Switchover
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Depending on the manufacturer, a heat pump may be designed
to satisfy a dominant heating load or dominant cooling load. A
reversing valve on the heat pump is used to switch between
heating and cooling and is energized with either an O or B
terminal on the heat pump. The House Control 406 has an
O/B output which can operate in the following ways:
Rc1 Y1
406
O/B
R
Y
O
With a geo source heat pump selected, the 406 will stage on
sequentially, but turns off both stages at once. This allows
the ground to naturally recover better since there are longer
periods of time between the heat pump transferring heat to
or from the ground source.
GEO Source Staging
Longer times between cycles
Stage 2 ON (Y2)
Stage 1 ON (Y1)
O = Heat pump normally operates in heat mode. Energize
O to operate the heat pump in cool mode
•
Stage Delay
The House Control 406 stages two heat pumps or a two-stage
heat pump automatically. A manual stage delay can also be
set between 2 and 20 minutes which forces the second stage
to remain off for this adjustable amount of time. Use the HP2
DELAY setting in the Adjust Menu to select either an automatic
or manual stage delay when two heat pump stages have been
configured (HP TYPE = 2STG or ROT).
Boiler Minimum Protection
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When operating a non-condensing boiler, it is important to
prevent cool water from returning to the boiler. Cold return
water temperatures create flue gas condensation, which if left
too long, can severely damage the boiler.
If VAR is selected as a backup type, the variable speed pump
will reduce its speed in order to maintain the boiler sensor
above the BOIL MIN setting. The BOIL MIN setting is the
lowest water temperature that the control is allowed to use
as a boiler target.
If the boiler supply water temperature is cooler than the boiler
minimum setting, the control reduces the output of the variable
speed pump. This limits the amount of cool return water to
the boiler and allows the boiler return water temperature to
recover. Once the boiler supply temperature exceeds the
boiler minimum setting, the variable speed pump will return
to normal operation.
Maximum Targets
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The control has a maximum target of + 10°F (+5.5°C) higher
than the DSGN setting for all heating curves. The control will
operate the boiler so that the boiler supply temperature will
never exceed 210°F (99.0°C).
Note:
The Variable Speed Pump does not provide boiler minimum
protections when the BOIL TYPE is set to EMS1 or EMS2.
