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Heat Cool Operation
Mode - ----- - ---- - - - --------- ---------------------
- ------------- - - - ---------------------------
There are five different modes that the heat pump and backup
can operate in. Use the MODE setting in the Adjust Menu to
select one of the following modes:
AUTO
The heat pump and backup will automatically switchover
between heat and cool mode.
COOL
While in cool mode, the heat pump will satisfy any cooling
calls from the zones on the Tank and Mix bus. The backup
will operate automatically to satisfy DHW and Setpoint calls
for heat on the Boil bus. "Cool" is displayed in the Mode status
field while in cool mode.
Status Field
Note: For hydronic cooling with a fancoil, use tekmarNet® 2
thermostat 530 or tekmarNet® 4 thermostat 540 with a date
code of December 2011 or newer.
HEAT
While in heat mode, the heat pump will satisfy any heating
calls from the zones on the Tank and Mix bus. The backup
will operate automatically to satisfy DHW, Setpoint, Tank, Mix
and Boil calls for heat. "Heat" is displayed in the Mode status
field while in heat mode.
Status Field
BKUP (Backup)
While in backup mode, the heat pump is disabled. The backup
will operate automatically to satisfy DHW, Setpoint, Tank, Mix
and Boil calls for heat. "Backup" is displayed in the Mode status
field while in backup mode.
Status Field
OFF
While in off mode, the heat pump and backup are disabled.
Interlock Delay ----------------------- ------ -----
----------------------------------
The interlock delay is the minimum time between heat/cool
switchovers while in the AUTO mode. Use the INTERLOCK
setting in the Adjust Menu to select an interlock time between
10 minutes and 180 minutes.
Switchover --- - - ----------------- ------ ----- -----
--------------------------------------
Switchover is determined by polling the thermostats on the
Tank and Mix bus. When enough thermostats are calling for
the opposite mode and the interlock delay has elapsed, a
switchover will occur. This ensures that the system actually
requires the new tank mode before switching over. Switchover
includes purging and preheat or precool.
Purging
Once Switchover begins, the heat pump is forced off. All zones
that are off remain off and all zones that become satisfied and
turn off also remain off. The remaining zones are allowed to
continue calling for 30 minutes or until the tank temperature
changes by 15°F (8°C). This allows the tank to be purged
before the heat pump is allowed to switch modes and reverse
the water temperature of the tank. While this is happening,
© 2011
D 406 - 12/11
the words "PURGING HEAT" or "PURGING COOL" will be
displayed in the view menu depending if the tank is currently
in the heat or cool mode.
Pre-Heat or Pre-Cool
Once the purging has completed, the heat pump is allowed
to preheat or precool the tank. All zones are prevented from
calling for 30 minutes or until the tank temperature reaches
within 10°F (5.5°C) of its new target. This allows time for the
heat pump to switch the tank temperature to its new target
before turning on zones again.
Switchover from
Heat to Cool Mode
Floor Cooling--------------------------- -- -- -- -- -
------------------------------------
Floor cooling is a form of radiant base load cooling. It reduces
the sensible cooling load, and care must be taken to avoid
removing moisture from the air causing condensation (latent
cooling). It works well in zones with lots of glass and high solar
gains by extracting heat away from the slab before it is able to
heat the room. 'Floor' is displayed in the Mode status field while
doing floor cooling.
Status Field
Enable Floor Cooling
For floor cooling to occur, a compatible tekmarNet
must have floor cooling turned on. Use the FLOOR COOL (or
F C) setting in the thermostat to turn floor cooling ON.
With Humidity Sensor
In areas where there is a potential for condensation to form
on the cooling surface, floor cooling requires at least one
humidity sensor on the network. The humidity sensor measures
relative humidity. Knowing the relative humidity and the room
temperature, the House Control 406 is able to calculate the
dewpoint temperature. Keeping the surface temperature of
the slab above dewpoint while doing floor cooling will prevent
condensation from forming.
For best results, multiple humidity sensors may be used.
The House Control 406 will choose the zone with the highest
dewpoint to calculate the floor cooling target.
Set the DEW POINT item in the Adjust Menu to ON for floor
cooling with a humidity sensor on the network.
34 of 48
Section C
Switchover from
Cool to Heat Mode
®
thermostat
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