tekmar 262 Boiler Control Installation User Manual
Page 8
8 of 36
Copyright © D 262 -
12/08
ROOM OCC & UNOCC
(ROOM)
(
CHARACTERIZED
HEATING
CURVE
)
The ROOM is the desired room temperature for the boiler zone(s) and it provides a parallel shift of the
Characterized Heating Curve.
The room temperature desired by the occupants is often different from the designed 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. If the
Setback / None DIP switch is set to Setback, a ROOM setting must be made for both the Occupied and UnOccupied modes.
TERMINAL UNITS (TERMINAL)
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. The 262 provides for selection
between six different terminal unit types: two types of hydronic radiant floor heat, fancoil, fin–
tube convector, radiator, and baseboard.
Hydronic Radiant Floor (HRF 1)
HRF 1 is a heavy, or high mass, hydronic radiant floor system. 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.
Hydronic Radiant Floor (HRF 2)
HRF 2 is a light, or low mass, hydronic radiant floor system. Most commonly, 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 subfloor and the surface. This type of radiant
system has a relatively low thermal mass and responds faster than a high mass system.
Fancoil (COIL)
A fancoil terminal unit or air handling unit (AHU) consists of an 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 (CONV)
A convector terminal unit is made up of a heating element encased in fins. 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 is dependant on the supply
water temperature to the heating element and the room air temperature.
Radiator (RAD)
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 (BASE)
A baseboard terminal unit is similar to a radiator, but has a low profile and is installed at the
base of the wall. The amount of heat transferred by radiation from a baseboard is greater
than that from a fin-tube convector.
BOILER TARGET TEMPERATURE (BOIL TRG)
(
RESET
RATIO
&
CHARACTERIZED
HEATING
CURVE
)
The Boil TRG temperature is determined from either the
Characterized Heating Curve or the Reset Ratio settings and the outdoor air
temperature and optionally indoor temperature feed back. The control displays the temperature that it is currently trying to maintain as
the boiler supply temperature. If the control does not presently have a requirement for heat, it displays “- - -” in the LCD.
BOILER OPERATION
When the 262 determines that boiler operation is required, the
Boiler stage contact(s) (11 and 12 and/or 13 and 14) close. While the
Boiler contact(s) is closed, the burner and stage segment in the LCD is displayed.
BOILER PUMP (P1) OPERATION
The
Boiler Pump contact (P1, terminal 8) closes whenever there is a Boiler demand and the 262 is not in WWSD. If 10K = INDR or SLAB,
the control receives a boiler demand and the Boil TRG temperature is below the Boil MIN setting, the boiler pump may continue to operate
after the boiler demand is removed. For boiler pump contact operation during either DHW and / or Setpoint operation, refer to the DHW,
and Setpoint Section D.
Soft Start (SOF STRT)
The SOF STRT function allows the 262 to slowly ramp the water temperature up to the required supply temperature. By allowing the
temperature in the system to be adjusted slowly, the control reduces any thermal expansion noises and stresses that may be caused
by a quick change in supply water temperature.
HRF 1
HRF 2
COIL
CONV
RAD
BASE