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© 2011
D 406 - 12/11
Hydronic Operation
Section D
Cool Setpoint
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For a cooling call other than floor cooling, the House Control
406 will operate the bus at an adjustable cooling setpoint.
Use the COOL SETP setting in the Adjust Menu to select a
cooling setpoint.
Hydronic Heat & Cool Calls
----------------------
----------------------
When a thermostat, or other
tekmarNet
®
device calls for heating
or cooling, the House Control 406 will register the call on the
corresponding bus and display the call in the “Calls” box of the
status field. Calls for heating or cooling may come from the
tank or mix bus. The boil bus may only call for heating.
Status Field
Warm Weather Shut Down (WWSD)
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--------------
During warmer weather, heating of the rooms is typically no
longer required. To prevent energy waste from unnecessary
heat pump and backup operation, the control goes into Warm
Outdoor Temperature Reset
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---------------------
Once a space heating call is present, the target water tem-
perature for that bus is determined using outdoor temperature
reset together with indoor temperature feedback from the
thermostats. A heating curve is used for each bus to determine
the outdoor temperature reset calculation. The heating curve
operates based on the principle that a buildings heat loss
increases with colder outdoor temperatures. See the default
heating curves for each bus below:
Outdoor Design
The outdoor design is the lowest outdoor temperature on the
typical coldest day of the year. At this outdoor temperature,
the heating curve will calculate the design water temperature
to be the target. Use the OUT DSGN setting in the Adjust
Menu to select an appropriate outdoor design temperature
for your city.
Design Water Temperature
There are up to three design water temperatures to set on
the House Control 406 depending on the water temperatures
configured. These are: boil design, mix design and tank design.
The House Control 406 will target the design water temperature
when the outdoor temperature reaches the outdoor design.
These two parameters set the upper point for each heating
curve. Adjust the BOIL DSGN, MIX DSGN, and TANK DSGN
settings in the Adjust Menu.
Boiler and Tank Minimum
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The BOIL MIN and TANK MIN settings in the Adjust Menu set
the lowest water temperature that the control is allowed to use
as the boiler target and tank target respectively.
It is useful to set a minimum target water temperature when
using a fan coil to prevent blowing cold air into the room.
Default Heating Curves
Boil Design
Tank & Mix
Design
180°F
110°F
70°F
70°F
10°F
Outdoor Design
Decreasing Outdoor Temperatures
Increasing W
a
ter T
e
mper
atures
Outdoor Design 10°F
70°F
70°F
140°F
Heating Curves
with Minimums
Increasing W
a
ter T
e
mperatures
Decreasing Outdoor Temperatures
Boil Min
90°F
Tank Min
Weather Shut Down (WWSD) when the outdoor temperature
rises above the WWSD temperature. Use the WWSD OCC
and WWSD UNOC settings in the Adjust Menu to set an ap-
propriate WWSD temperature.
Without Humidity Sensor
Floor cooling may be performed without a humidity sensor.
This operation is only recommended in dry areas where
humidity is not a concern. Set the DEW POINT item in the
Adjust Menu to OFF for floor cooling without a humidity sensor
on the network.
Conditions For Floor Cooling
The House Control 406 will enter into floor cooling when the
following conditions have been met:
1. The 406 is in Warm Weather Shut Down (WWSD)
2. There has been no heat calls for 2 hours
3. There are no cooling or dehumidification calls on the bus that
cause the target to go below the dewpoint temperature
At the thermostat, floor cooling will stop when the room tem-
perature cools to the heating target plus 3°F (1.5°C).
Floor Cooling Target
During floor cooling, the target water temperature is the
higher of:
1. The dewpoint temperature plus 2°F (1°C) if DEW POINT
= ON, or
2. The COOL MIN setting in the Adjust Menu
This ensures the surface of the slab never reaches the dewpoint
temperature causing moisture to condense.
Note:
For floor cooling, use tekmarNet® 2 thermostats 527,
528, 529, 530 or tekmarNet® 4 thermostats 537, 538, and 540
with a date code of
December 2011
or newer.
