tekmar 356 Mixing Control User Manual

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CHARACTERIZED HEATING CURVE

When used as a mixing reset control, the 356 varies the supply water temperature based on the outdoor air temperature. The control
takes into account the type of terminal unit that the system is using. Since different types of terminal units transfer heat to a space
using different proportions of radiation, convection and conduction, the supply water temperature must be controlled differently. Once
the control is told what type of terminal unit is used, the control loads the factory defaults and varies the supply water temperature
according to the type of terminal unit. This improves the control of the air temperature in the building.

MIXING TARGET TEMPERATURE (MIX TARGET)

When used as a mixing reset control, the MIX TARGET temperature is determined from the

Characterized Heating Curve settings

and outdoor air temperature. When used as a setpoint control, the installer will set the MIX TARGET temperature. The control displays
the temperature that it is currently trying to maintain as the mixing supply temperature. If the control does not have a mixing demand,
“- - -” is displayed as the MIX TARGET.

Section B2: Installer

OUTDOOR DESIGN (OUTDR DSGN)

The OUTDR DSGN is the outdoor air temperature that is the typical
coldest temperature of the year where the building is located. This tem-
perature is used when doing the heat loss calculations for the building.
If a cold outdoor design temperature is selected, the mixing supply tem-
perature rises gradually as the outdoor temperature drops. If a warm
outdoor design temperature is selected, the mixing supply temperature
rises rapidly as the outdoor temperature drops.

SETPOINT OPERATION (MIX TARGET)

For setpoint operation, set the OUTDR DSGN to OFF. The MIX TAR-
GET becomes the setpoint supply temperature that the control is to
maintain. The MIX TARGET temperature is set by the installer in the
ADJUST menu. An outdoor sensor is not required during this mode of
operation.

ROOM (ROOM)

The ROOM is the desired room temperature for the mixing zones, and
it provides a parallel shift of the

Characterized Heating Curve. The room

temperature desired by the occupants is often different from the design
indoor temperature (MIX INDR). If the room temperature is not correct,
adjusting the ROOM setting increases or decreases the amount of heat
available to the building.

TERMINAL UNITS

When using a

Characterized Heating Curve, the control requires the selection of a terminal unit. The terminal unit determines the

shape of the

Characterized Heating Curve according to how the terminal unit delivers heat into the building space (refer to Essay

E 003). The 356 provides for selection between six different terminal unit types: two types of radiant floor heat, fancoil, fin-tube
convector, radiator and baseboard. When a terminal unit is selected, the control automatically loads the design supply temperature
(MIX DSGN) and maximum supply temperature (MIX MAX). The factory defaults are listed below. To change defaults, refer to section
B3. If a default has been changed, refer to section A to reload the factory defaults.

150

°F (66°C)

170

°F (77°C)

MIX DSGN
MIX MAX

Terminal Unit

190

°F (88°C)

210

°F (99°C)

High Mass Radiant

(1)

120

°F (49°C)

140

°F (60°C)

Low Mass Radiant

(2)

Fancoil

(3)

140

°F (60°C)

160

°F (71°C)

Fin-tube Convector

(4)

180

°F (82°C)

200

°F (93°C)

Radiator

(5)

160

°F (71°C)

180

°F (82°C)

Baseboard

(6)

Decreasing Outdoor Temperature

Increasing W

ater

emperature

cold

MIX INDR

MIX DSGN

warm

OUTDR

DSGN

Decreasing Outdoor Temperature

Increasing W

ater

emperature

MIX INDR

sig

ROOM