tekmar 374 Universal Reset Control User Manual

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Low Mass Radiant (2)

This type of radiant heating system is either attached to the bottom of a wood sub-floor,
suspended in the joist space, or sandwiched between the sub-floor and the surface.
This type of radiant system has a relatively low thermal mass and responds faster than
a high mass system.

Fancoil (3)

A fancoil terminal unit or Air Handling Unit (AHU) consists of a hydronic heating coil and
either a fan or blower. Air is forced across the coil at a constant velocity by the fan or
blower, and is then delivered into the building space.

Fin-Tube Convector (4)

A convector terminal unit is made up of a heating element with fins on it. This type of
terminal unit relies on the natural convection of air across the heating element to deliver
heated air into the space. The amount of natural convection to the space is dependant
on the supply water temperature to the heating element and the room air temperature.

Radiator (5)

A radiator terminal unit has a large heated surface that is exposed to the room. A radiator
provides heat to the room through radiant heat transfer and natural convection.

Baseboard (6)

A baseboard terminal unit is similar to a radiator, but has a low profile and is installed at
the base of the wall. The proportion of heat transferred by radiation from a baseboard is
greater than that from a fin-tube convector.

OUTDOOR DESIGN TEMPERATURE

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

WARM WEATHER SHUT DOWN (OCC AND UNOCC)

The Warm Weather Shut Down (

WWSD) disables the space heating system during warm outdoor weather. There is a separate

WWSD for both the occupied and the unoccupied periods. When the outdoor air temperature rises above the WWSD setting, the
control turns on the

WWSD pointer in the display and does not operate the space heating system to satisfy boiler, mix 1 or mix 2

demands. Mix 2 setpoint demands remain active. The control does respond to a DHW demand or a setpoint demand and operates
as described in sections C and D.

SETBACK

To provide greater energy savings, the control has a setback feature. With setback, the supply water temperature in the system
is reduced when the building is unoccupied. By reducing the supply water temperature, the air temperature in the space may be
reduced even when thermostat(s) are not turned down.

The control has an internal setback timer with two events per day on a 24 hour, a 5-1-1 day
or a 7 day schedule.

The control also has an external setback input. Any time the

UnO Sw (6) and the Com (7)

are shorted together, the control operates in the unoccupied mode.

The external setback overrides the internal setback timer schedule to place the control into
the unoccupied period.

When in the unoccupied mode, the

UNOCC segment is displayed in the LCD. The control

adjusts the supply water temperature based on the

UNOCC settings made in the control.

Uno

Com

Timer Switch

FACTORY DEFAULTS

The control comes preset with several factory defaults. These defaults are based on the terminal unit selection (see section B for
Boilers and section E for Mixing Devices). To fine-tune building requirements, these defaults may be changed.

To reload the factory default, power down the control and wait for 10 seconds. Power up the control while simultaneously holding the
Menu and

▼ buttons. An E01 error occurs forcing the installer to go through the ADJUST menu to ensure the settings are correct.