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© 2011
D 406 - 12/11
VAR (Variable Speed Pump)
A boiler is the backup heat source. Backup heat is transferred
from the boiler loop to the tank loop with the Variable Speed
Pump. This is only selectable if a boiler water temperature
has been selected and no mixing water temperature has been
selected. Once enabled, the Variable Speed Pump will operate
to maintain the desired tank target.
Note:
Boiler return protection is available when selecting
this type of backup. The Variable Speed Pump operates at
minimum speed whenever the boiler supply temperature falls
below the boiler minimum setting or when the control is doing
DHW or Setpoint priority.
Expansion
Tank
Variable Speed
Pump
To
System
Storage
Tank
Non-Condensing
Boiler
Water/Water
Heat Pump
Boiler
Sensor
Tank
Sensor
HP Return
Sensor
For Variable Speed Pump backup, see A406-4
Selecting a Boiler Type
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A boiler may be used as a backup heat source to supplement
the heat pump during heating mode. The boiler may also heat
domestic hot water, setpoint loads and space heating zones on
the boiler bus. The House Control 406 has five boiler types to
choose from. Use the BOIL TYPE setting in the Adjust Menu
to select one of the following:
1 STG
The Backup relay is used to operate a single stage on/off boiler
to maintain the boiler target temperature.
0-10
The Mod dc/mA output uses 0-10 V (dc) to operate a modulating
boiler to maintain the boiler target temperature. The Backup
relay is also used to give a boiler enable to allow the modulating
boiler to go through the ignition sequence. The Backup relay
may not be required on all modulating boilers.
4-20
The Mod dc/mA output uses 4-20 mA to operate a modulating
boiler to maintain the boiler target temperature. The Backup
relay is also used to give a boiler enable to allow the modulating
boiler to go through the ignition sequence. The Backup relay
may not be required on all modulating boilers.
EMS1
The Mod dc/mA output uses 0-10 V (dc) to communicate a
desired boiler target water temperature to a tekmar stager that
accepts an EMS signal. 1 V (dc) corresponds to 50°F (10°C)
and 10 V (dc) corresponds to 210°F (99°C).
HP Loop Pump Operation
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-----------------------
Due to different piping arrangements, the HP Loop Pump may
operate in two different ways. Use the HP LOOP setting in the
Adjust Menu to select the proper operation for this pump.
INT (Intermittent)
The HP Loop Pump will operate together with the heat pump
compressor including pre-purge and post-purge times. This
operation is suitable when using a 3-port or 4-port storage tank
to hydraulically isolate the HP Loop from the Tank Loop.
Expansion
Tank
To System
HP Loop
Pump
Tank System
Pump
Water/Water
Heat Pump
2-Port
Storage
Tank
ON
The HP Loop Pump will operate together with the heat pump
compressor including pre-purge and post-purge times and
it will operate whenever water is being pumped into or away
from the storage tank. This includes:
When there is a call on the Tank Bus
When there is a call on the Mix Bus
When the Transfer Pump is on
This operation is suitable when using a 2-port storage tank
and primary/secondary piping is used to hydraulically isolate
the HP Loop from the Tank Loop.
•
•
•
Expansion
Tank
To System
HP Loop
Pump
Tank System
Pump
Water/Water
Heat Pump
3-Port
Storage
Tank
Expansion
Tank
To System
HP Loop
Pump
Tank System
Pump
Water/Water
Heat Pump
4-Port
Storage
Tank
3-Port Storage Tank Piping, HP LOOP = INT
4-Port Storage Tank Piping, HP LOOP = INT
2-Port Storage Tank Piping, HP LOOP = ON
EMS2
The Mod dc/mA output uses 0-10 V (dc) to communicate
a desired boiler target water temperature to a Viessmann
modulating boiler. 0 V (dc) corresponds to off, 2.2 V (dc)
corresponds to 81°F (27°C), and 10 V (dc) corresponds to
176°F (80°C).
