Mixing characterized heating curve – tekmar 361 Mixing Control User Manual

Page 8

03/09

8 of 20

MIXING MINIMUM (MIX MIN)

The MIX MIN is the lowest temperature that the control is allowed to use
as a MIX TARGET temperature. During mild conditions, if the 361 cal-
culates a MIX TARGET temperature that is below the MIX MIN setting,
the MIX TARGET temperature is adjusted to match the MIX MIN set-
ting. During this condition, the MIN segment will be displayed in the
LCD when either the MIX TARGET or MIX temperature is being viewed.
If an indoor sensor is used, and the 361 is operating at the MIX MIN
temperature, the system pump is cycled using Pulse Width Modulation
(PWM) with a 15 minute cycle length. By cycling the system pump and
controlling the flow of supply water, the control provides an average
supply water temperature to the system. This average temperature is
equal to the original MIX TARGET. This minimizes overheating of the
zone while the control is operating at the MIX MIN temperature.

WARM WEATHER SHUT DOWN (WWSD) OCC & UNOCC

When the outdoor air temperature rises above the WWSD setting, the
361 turns on the WWSD segment in the display. When the control is in
Warm Weather Shut Down, the

Mixing Demand pointer is displayed, if

there is a demand. However, the control does not operate the heating
system to satisfy this demand. If the control is in setpoint mode, the
WWSD feature is not functional.

Section C: Boiler Operation

Section C1

General Operation

Section C2

Boiler Sensor

Placement

Section C1: General Operation

BOILER OPERATION

When the 361 determines that boiler operation is required, the

Boiler contact terminals (9 and 10) close. While the Boiler contact is

closed, the burner segment in the LCD is displayed.

BOILER MINIMUM (BOIL MIN)

Most boilers require a minimum water temperature in order to prevent flue gas condensation. The BOIL MIN adjustment is set to the
boiler manufacturer’s minimum recommended operating temperature. Only when the boiler temperature is measured by a boiler
sensor can the 361 provide boiler protection. In this case, when the boiler is firing and the boiler temperature is below the BOIL MIN
setting, the 361 turns on the MIN segment and reduces the heating load on the boiler by limiting the output of the variable speed
injection pump. If the installed boiler is designed for low temperature operation, set the BOIL MIN adjustment to OFF.

BOILER PROTECTION

Refer to section A for a description of boiler protection.

WWSD OCC

(21)

(32)

110

(43)

130

(54)

150

(66)

170

(77)

190

(88)

Outdoor Air Temperature

Supply W

ater

emperature

210

°F

(99

°C)

-20

(-29)

(-18)

(-7)

(5)

(16)

°F

(27

°C)

MIX DSGN

MIX MAX

MIX MIN

WWSD UNOCC

MIX INDR

OUTDR DSGN

Mixing Characterized

Heating Curve

(10)

ROOM UNOCC

ROOM OCC