tekmar 545 Thermostat Installation - Manual (Page 34)

© 2008 D 545 - 07/08 34 of 40
Away Hold Section O
Away Away
Away Away
62°F
62°F
62°F
62°F
To set the temperature while the occupants are away, use the
Permanent Away 2 scene. This scene changes all thermostats
on the network to the Away temperature setting. If there is
an Outdoor Reset Module on the tN4 communication bus,
the boiler no longer responds to domestic hot water calls
for heat. Setpoint demands continue to operate as in the
Occupied mode. • • To set the number of days away, go to the Scene menu
and select Away Hold.
When set to Infinite, the Permanent Away 2 scene remains
until a new scene is selected. If you know in advance how
long the building occupant will be away, you can adjust Away
Hold to the number of days. Once the number of days have
elapsed, the thermostat automatically changes from the
Permanent Away 2 scene to previous permanent scene.
Example: The home occupants are traveling for 14 days.
They want the home to be at the Away temperatures
for 14 days and then automatically return to the normal
schedule.
•
• Away Hold is set to 14 days.
•
• Scene is changed to Permanent Away 2.
Away Temperatures
An Away temperature setting exists for both heating and
cooling. By default, the Set Heat Away temperature is set
to 62°F (16.5°C) and the Set Cool Away temperature is
set to 85°F (29.5°C).
•
• To set the Away temperature, go to the Adjust menu
and select the Set Heat Away and the Set Cool Away
items. The Access Level must be set to Installer or
Advanced.
Length of Time Away
The Away Hold feature allows you to set the number of
days the Away temperature applies.
Radiant Base Load Section P
Base Load
Occupied
Unoccupied
Time
Use the Radiant Base Load feature when operating radiant
floor heating in conjunction with a fast acting secondary heat
source. The Radiant base Load feature is only available
when a floor sensor is not installed. A time lag occurs
with radiant floor heating due to the large thermal mass of
concrete floors. This effect is evident when the thermostat
temperature setting is increased and the radiant floor takes
a while to reach the specified temperature.
Likewise, when the room air temperature setting is
decreased the floor temperature slowly decreases. This
can be described as a “flywheel” effect.
This flywheel effect is particularly noticeable when there is
a large amount of solar gain in the building. The building
temperature overshoots the desired temperature while
the sun rises and the temperature undershoots when the
sun sets.
The total heating load can be broken down into two portions.
One portion is a heat load that remains constant for long
periods of time. This is defined as the base load. The other
portion of the heat load is consistently changing over a
period of time due to occupant comfort, cycling of heating
equipment, temperature settings in the setback schedule
and solar gain effects throughout a day. This portion of the
heating load is defined as the dynamic heating load.
The Radiant Base Load feature counteracts the flywheel
effect by using the radiant floor to only heat the base load.
The secondary heating system makes up the difference
between the base load and the dynamic load. Therefore,
the amount of radiant floor heating compared to the total
heating load is less than 100%.
•
• To adjust Radiant Base Load, go to the Adjust menu
and set the H1 Load item.
In the Hi setting, the radiant floor heating tries to fully
heat the entire heating load. In the Lo setting, the radiant
floor heating only makes up a small portion of the overall
heating load. The thermostat also includes a 2 and a 3
setting that provides intermediate steps between the Lo
and Hi settings.