tekmar 263 Boiler Control - Manual (Page 13)

13 of 36 © 2009 D 263 - 03/09
TERMINAL UNITS
The control provides for a 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,
maximum supply temperature, and minimum supply temperature. The factory defaults are listed below. These factory defaults can
be changed to better match the installed system.
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 MAX 140°F (60°C) 160°F (71°C) 210°F (99°C) 200°F (93°C) 180°F (82°C) 170°F (77°C)
BOIL MIN OFF OFF 140°F (60°C) 140°F (60°C) 140°F (60°C) 140°F (60°C)
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.
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 dependent
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.
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. When the control is in WWSD, the Boiler Demand pointer is displayed if there is
a boiler demand. However, the control does not operate the heating system to satisfy this demand. The control does respond to a
DHW demand or a setpoint demand and operates as described in sections E and F.
BOOST
When the control changes from the unoccupied mode to the occupied mode,
it enters into a boosting mode. In this mode, the supply water temperature to
the system is raised above its normal values for a period of time to provide a
faster recovery from the setback temperature of the building. The maximum
length of the boost is selected using the BST setting. Self Adjusting
Water Temperature
Boil Target (Occupied)
Boost
Boil Target (UnOccupied)
Boost setting - 20 minutes to 8 hours
Time