tekmar 279 Steam Control User Manual

Page 9

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Optimum Start

Section J

The control includes an optimum start feature that is available
in the Adjust menu when indoor sensors are installed and
the Setback / Off switch setting is set to Setback. The
optimum start can be set to either on or off.

When a programmable schedule is used to lower the
building temperature at night, there is a time delay to
increase the building temperature from the Unoccupied to
the Occupied temperature. When optimum start is turned
on, the control uses the indoor sensor to learn the heat up
rate of the building. The control can then accurately predict
when the control should increase the heating cycle on time
so that the building reaches the Occupied temperature at
the scheduled time. Optimum Start is shown on the display
while optimum start is in effect.

Boost

Section K

The control includes a boost feature that is available in the
Adjust menu when indoor sensors are not installed and the
Setback / Off switch setting is set to Setback.

When a programmable schedule is used to lower the
building temperature at night, there is a time delay to
increase the building temperature from the Unoccupied to
Occupied temperature. The control shortens the recovery
time by determining how long the steam boiler needs to
operate at 100% on time of a heating cycle and the boost
can continue through multiple heating cycles. The length
of the boost is determined by the temperature difference

between Occupied and Unoccupied and the duration of time
in setback. The Boost setting allows the installer to set the
maximum amount of time that Boost can remain in effect.
Boost is shown on the display while boost is in effect.

Optimum Start

10 P.M.

5A.M.

8A.M.

Occ

70°F (21°C)

UnOcc

65°F (18°C)

Room
Temp.

Recovery Period

Optimum
Start

Setback

Period

Building

Temperature

% On Time

Per Cycle

Occupied

Unoccupied

Setback Period

Boost

Limited Unoccupied

Section L

The control includes a Limited Unoccupied feature that is
available in the Adjust menu. When the Limited Unoccupied
is set to on and the heating cycle reaches 85% on time, the
control is prevented from going into the Unoccupied mode in
order to avoid long recovery times. If the control is already
in the Unoccupied mode and the outdoor temperature drops

so that the heating cycle on time exceeds 85%, the control
will switch back into the Occupied mode. When the Limited
Unoccupied is set to off, the control continues to operate
on the regular Occupied/Unoccupied schedule, regardless
of the heating cycle on time.

Alert Relay Operation

Section M

The alert relays can be used to connect to security systems,
alarm panels or telephone dialers to provide an alert signal
should the control have an error message present.

Note: The 279 is not a UL approved alarm panel.

Alert 1 Relay

The Alert 1 Relay closes when the control has an E01
Memory Error message, or when either Room 1 or Room
2 sensor measures a temperature below 38°F (3.5°C).

Alert 2 Relay

The Alert 2 Relay closes when the outdoor, condensate,
room 1, room 2, or DHW tankless coil sensor has either
an open or short circuit.