ROOM OCC & UNOCC (ROOM)
The ROOM is the desired room temperature for the boiler 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 (BOIL INDR). If the room temperature is not correct,
adjusting the ROOM setting increases or decreases the amount of
heat available to the building. A ROOM setting is available for both the
occupied (Day) and unoccupied (Night) modes.
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
256 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 (BOIL DSGN) and
minimum supply temperature (BOIL MIN). 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.
High Mass Radiant (1)
This type of a hydronic radiant floor is embedded in either a thick concrete or gypsum
pour. This heating system has a large thermal mass and is slow acting.
Default values: BOIL DSGN = 120°F (49°C), BOIL MIN = OFF
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.
Default values: BOIL DSGN = 140°F (60°C), BOIL MIN = OFF
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.
Default values: BOIL DSGN = 190°F (88°C), BOIL MIN = 140°F (60°C)
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 dependent
on the supply water temperature to the heating element and the room air temperature.
Default values: BOIL DSGN = 180°F (82°C), BOIL MIN = 140°F (60°C)
Terminal Unit
High Mass Radiant
(1)
Low Mass Radiant
(2)
Fancoil
(3)
Fin-tube Convector
(4)
Radiator
(5)
Baseboard
(6)
BOIL DSGN
120°F (49°C)
140°F (60°C)
190°F (88°C)
180°F (82°C)
160°F (71°C)
150°F (66°C)
BOIL MIN
OFF
OFF
140°F (60°C)
140°F(60°C)
140°F (60°C)
140°F (60°C)
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© 2019 tekmar 256_D - 09/19
