tekmar 403 House Control Installation - Manual (Page 21)

21 of 32 © 2011 D 403 - 07/11
Sequence of Operation
tekmarNet ® System Section A
tekmarNet ® is a family of products that use communication
to operate the HVAC system in a comfortable and efficient
manner. The House Control is the central component in
a tekmarNet
® system and requires tekmarNet ® 2 (tN2)
Thermostats to be directly connected to the control.
The tekmarNet ® 4 (tN4) Expansion terminals can link the
House Control with other tekmarNet ® components:
Wiring Centers 313, 314, 315, 316 - Add additional zones
tN2 and tN4 Thermostats - Add thermostats
tN4 Timer 033 - Adds 4 programmable schedules
tN4 User Switch 479 - Provides a system override for
vacations and holidays
tN4 Setpoint Control 161 - Control hot tubs, pools and
more •
•
•
•
•
Mix Temperature Reset Operation Section B
When an onboard tN2 Thermostat calls for heat, the House
Control registers a Mix call for hydronic heating.
When a device connected to the tN4 Mix Expansion
terminals calls for heat, the House Control registers a Mix
Expansion Call for hydronic heating on the mix loop.
Mix
Calls
Mix Exp
Calls
Mix Call or Mix Expansion Call ----------------------------------------------------------------------- -----------------------------------------------------------------------
Mix Target -------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------
When there are no Mix or Mix Expansion calls, the mix
target in the View menu on the display will show ‘– – –’ to
indicate there is no requirement for mixing operation.
Once a Mix Call or Mix Expansion Call is present, a mix
target is determined by the control using the mixing heating
curve (mix design and outdoor design settings) together
with indoor temperature feedback from the thermostats.
The heating curve operates based on the principle that
a buildings heat loss increases with colder outdoor
temperatures. The calculated Mix Target will be shown in
the View menu on the display.
Mix Maximum
The control has a fixed mix maximum temperature of +10°F
(+5.5°C) higher than the Mix Design setting. When this
occurs, the “MAX” segment will display when viewing the
mix target or mix supply temperature in the view menu.
Mix Heating Curve
(70°F Outdoor,
70°F Mix Supply)
Decreasing Outdoor Temperatures
Increasing W
a
ter T
e
mperatures
(Outdoor Design,
Mix Design)
Mix Supply ------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------
Once a Mix Target water temperature has been calculated,
the House Control measures the temperature at the mix
supply sensor location and then operates the mixing device
to maintain the mix supply temperature. The heat source will
also be turned on and operated so that the mixing device
is able to maintain the mix target temperature. Boiler Minimum Protection
If the boiler supply water temperature is cooler than the
boiler minimum setting, the control reduces the output of the
mixing device. 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 mixing device will return
to normal operation.
Note: The mixing device does not provide boiler minimum
protection when the Boiler Type setting is EMS1 or EMS2.