tekmar 401 House Control Installation - Manual (Page 24)

© 2011 D 401 - 07/11 24 of 28
Auto Differential -------------------------------- --------------------------------
Both on-off and modulating boilers are operated with
a differential. In some cases, a modulating boiler must
be operated with a differential while operating at low
fire because this indicates the load is smaller than
the minimum modulation of the boiler. For modulating
boilers, the differential no longer applies once operating
the boiler above low fire.
The differential operates by closing the boiler contact
when the boiler supply water temperature is 1/2 of the
differential below the boiler target temperature. As the
supply temperature reaches 1/2 of the differential above
the boiler target temperature, the boiler is shut off.
+1/2 Differential
- 1/2 Differential
Boiler Target
Boiler On
Boiler Off
In order to decrease temperature swings and increase boiler
efficiency, the Auto Differential feature automatically adjusts
the operating differential of the boiler based on the heating
load. As the load increases, the differential will decrease
to minimize temperature swings. As the load decreases,
the differential will increase to prevent short cycling. This
can significantly improve operating efficiency and prevent
equipment failures through excessive cycling.
Off
Differential
Time
Heating Load
On
Pump Operation Section F
Pump Exercising ------------------------------ ------------------------------
The control operates each pump every three days for 10
seconds to help prevent corrosion and / or precipitate build
up on the pump components that can lead to pump seizure.
The “$aving” icon is displayed when energy is being saved.
The following features reduce energy consumption.
Network Schedules---------------------------- ----------------------------
Adding a schedule to a tekmarNet ® system is both easy
and valuable. A Timer 033 provides scheduling with up to
4 events per day for every tekmarNet
® Thermostat. Turning
down the room temperatures when they are unoccupied
reduces boiler on-time and energy consumption which
helps save money and the environment.
One-Touch Economy -------------------------- --------------------------
A User Switch 479 allows for one-touch overrides of the
system. For example, if leaving the building for vacation,
simply press the “Away” button and all the thermostats
will immediately operate at a lower temperature, instead
of having to walk around the building lowering the heating
temperature setting and raising the cooling temperature
setting on each thermostat.
DHW Tank During Away ----------------------- -----------------------
In addition to the One-Touch setback, a User Switch 479
also allows the user to press the ‘Away’ button and tell the
House Control 401 to ignore DHW Calls, preventing the
DHW tank from unnecessarily heating up when no one is
living in the building.
Warm Weather Shut Down (WWSD) ------------ ------------
During warmer weather, heating of the rooms is typically no
longer required. To prevent energy waste from unnecessary
boiler operation, the control goes into Warm Weather Shut
Energy Saving Features Section G
Down (WWSD) when the outdoor temperature rises above
the WWSD temperature set in the Adjust menu.
Further Savings!
Use a Timer 033 with programmable schedule #1 to
gain the WWSD Unoccupied setting. This provides an
additional WWSD temperature that can be set even lower
for Unoccupied and Sleep time periods.
This setting will appear after WWSD in the Adjust
menu if a Timer 033 or User Switch is present on the
system.
Zone Synchronization ------------------------- -------------------------
Another feature of the House Control is Zone Synchronization.
In typical zoned systems, the thermostats operate on a stand-
alone basis. This means that a zone turns on and off as
required without any regard for other zones. The net effect
is random operation of the zones causing short cycling of
the heat source. tekmarNet
® thermostats communicate to
ensure that their cycles are synchronized. Energy is saved
by ensuring zones requiring heat operate on the same cycle,
therefore reducing short cycling of the boiler.
Zone Post Purge ------------------------------ ------------------------------
When the last zone is nearly satisfied for heating, the boiler
is shut off and the zone pump continues to operate. This
purges the residual heat from the boiler into this zone. The
control continues this purge for a maximum of two minutes.
The control will stop the purge if the boiler supply temperature
drops below the boiler minimum setting.
•
The control ensures that no heat is supplied to the zones
during exercising.