37 of 48
© 2011
D 406 - 12/11
Use the SWITCHOVR setting in the Adjust Menu to select the
proper operation of the O/B terminal.
Rc1 Y1
406
O/B
R
Y
B
Backup Delay
-----------------------------------
-----------------------------------
To allow the heat pump to operate at full output for some
adjustable amount of time before the backup heat source is
allowed to come on, a backup delay is used. Use the BKUP
DLY setting in the Adjust Menu to set an appropriate backup
delay time. When OVR is selected, the backup source will
not be called upon for heat unless the MODE is set to BKUP
or the heat pump is locked out on high return temperature or
outdoor temperature. This ensures that the heat pump is being
used to its full potential during heating.
HP Return Water Temperature Limit
-------------
-------------
At certain return water temperatures, it may not be economi-
cal to keep the heat pump operating due to low coefficient of
performance (COP). This will occur in heating when the return
water temperature is too high, and in cooling when the return
water temperature is too low. These values will differ from
one heat pump to another. Use the HP RETURN MAX and HP
RETURN MIN
settings in the Adjust Menu to set the heat pump
return water temperature limits for heating and cooling.
DHW Operation
Section F
A DHW Call is required in order for the control to provide heat
to a DHW tank. Once the control registers a DHW Call, it will
display the DHW icon in the “Calls” box of the status field.
This can be done in one of three ways:
DHW Calls
---------------------------------------
---------------------------------------
DHW Tank Aquastat
If a DHW aquastat (mechanical switch) is used to apply a DHW
Call, the tank is heated to the aquastat temperature setting.
A dry contact is applied across the DHW Call terminals on
the House Control.
Use the DHW XCHG setting in the Adjust Menu to set the
boiler target required to satisfy this type of DHW call.
DHW Tank Sensor
A DHW tank sensor provides superior temperature control
of the tank compared to an aquastat. The House Control
automatically detects whether a DHW sensor is installed.
•
Status Field
Cooling
During cool weather, cooling of the rooms is typically no longer
required. The control shuts down the heat pump when the
outdoor temperature falls below an adjustable temperature to
prevent energy waste from unnecessary heat pump operation
during cooling. Use the Y COOLING CWSD setting in the Adjust
Menu to set the low outdoor air temperature limit for cooling.
Note:
the CWSD icon is displayed in status field of the display
when the outdoor temperature falls below either the BALNCE
PT or Y COOLING CWSD settings in the Adjust Menu.
Status Field
B = Heat pump normally operates in cool mode. Energize
B to operate the heat pump in heat mode
•
Outdoor Air Temperature Limit
------------------
------------------
Heating - For AIR Source Heat Pumps Only
At low outdoor air temperatures, it may not be economical to
keep an air source heat pump operating during heating due to
low COP. These values will differ from one air source heat pump
to another. Use the BALNCE PT setting in the Adjust Menu to
set the low outdoor air temperature limit for heating.
Heat Pump Differential
---------------------------
---------------------------
The differential operates by closing the Y1 contact when
the tank water temperature is 1/2 of the differential below
the tank target. As the tank temperature reaches 1/2 of
the differential above the tank target, the Y1 contact is
opened, turning the heat pump off.
+1/2 Differential
- 1/2 Differential
Tank Target
H.P. On
H.P. Off
DHW Mode
--------------------------------------
--------------------------------------
The control has five different settings available for DHW Mode
that affect pump operation. The required DHW Mode setting
will depend on the piping arrangement of the DHW tank and
whether or not priority for the DHW tank is necessary. DHW
Priority stops or limits the delivery of heat to the building heating
system while the DHW tank calls for heat. This allows for quick
DHW tank temperature recovery.
The upper limit of the DHW temperature is set by the DHW
OCC setting in the Adjust Menu. The DHW tank differential
is fixed to 6°F (3°C).
When using a DHW Tank Sensor, the boiler target is set
to the DHW OCC setting plus 40°F (22°C).
tekmarNet
®
Setpoint Control with Sensor
A DHW Call is provided through the tekmarNet
®
system. This
can be done through the tN4 Boil Expansion terminals with
a tekmarNet
®
setpoint device such as a Setpoint Control 161
or 162.
When using a tekmarNet
®
Setpoint Control, the boiler
target is set to the devices Exchange Supply setting.
•
•
