tekmar 557 Thermostat Installation - Manual (Page 36)

© 2014 557_D - 09/14
36 of 52 A Watts Water Technologies Company
Cooling Operation Section B
Set Cool Temperature ----------------------------------------------- -----------------------------------------------
The 557 can operate a two-stage heat pump or air conditioner to provide cooling
depending on the outdoor air temperature. In some cases, cooling is provided by a
chilled water fan coil. The illustration below shows when each of the available cooling
units are available. The “Cool On” symbol is shown on the display when the thermostat
is cooling.
Floor Cooling ------------------------------------------------------- -------------------------------------------------------
Floor cooling is designed to cool a building together with an air cooling system. Floor
cooling reduces part of the sensible cooling load, while the air cooling equipment
must cool the latent load (dehumidification) and the remaining sensible load.
The thermostat has the option to support floor cooling when connected to a heat
pump control using tekmarNet
® communication. The terminal unit type must be set
to be HRF1 or HRF2, the floor cooling setting must be set to On and the heating
system must be in Warm Weather Shut Down (WWSD). When the thermostat is set
to Mode Cool, the floor cooling turns on 1.0
° F (0.5 ° C) below the Set Cool setpoint.
This allows the floor cooling to operate for long periods of time while the air cooling
system cycles on and off to maintain the cooling setpoint. Floor cooling does not
operate below 64
° F (18.0 ° C).
Cooling Cold Weather Shut Down ------------------------------------- -------------------------------------
When the outdoor air temperature falls below the Cooling Cold Weather Shut Down
(CWSD) setting on the thermostat, the cooling system is shut off.
Warm Weather
Shut Down Cooling Cold
Weather Shutdown
Floor
Cooling Warmer Outdoor
Temperature
No Cooling