Multi-stage and Heat Pump Comfort-Set II thermostats are designed to determine the optimum time to activate the second stage. Simply raising the temperature in heating or lowering it in cooling will not always force the thermostat to bring the second stage on quickly. There is a time delay from 0-25 minutes if the system has been reaching your setpoint using the first stage. The time element (0-25 minutes) of the delay varies depending on the performance of the first stage. In Heating, for example, assume for the last 2 hours the thermostat is set on 70 and the room temperature is 70 with the equipment using only the first stage of heat. The thermostat calculates (internally) the performance of the system. Since the equipment is keeping the temperature within 1 degree of setpoint, the thermostat will delay second stage for a longer time if you manually raise the temperature or if the room temperature quickly changes. Once the second stage comes on, it will come on sooner the next time there is a difference between the setpoint and the room temperature. The net effect of the staging program is when the first stage is capable of making temperature the second stage will delay longer. When the thermostat calculates that first stage cannot make temperature in a reasonable time, the second stage will come on sooner. This is a built in function that automatically optimizes the use of additional stages of heat or cool. Most thermostat models have a method to bring the additional heat or cool stages on quickly for testing purposes listed in the installation instructions under the heading of "Testing Your Heat/Cool System".

AUX - Auxiliary Heat or the second stage of heat in the Heat mode. This is energized when the Heat Pump is not keeping up with the thermostat setting. It is normal operation with most pumps for the thermostat to call for auxiliary heat. If the auxiliary heat and emergency heat are using the same back-up heat source the thermostat may also show the Emergency Heat light whenever the Auxiliary heat is on. EMER - Emergency Heat. When switched to Emergency the thermostat bypasses the pump and uses the back-up heat. This is useful if the pump is not operating correctly or if the temperature outside is so cold that the pump is not economical to run. If the Auxiliary Heat and Emergency Heat are using the same back-up heat source the thermostat may show the Auxiliary and Emergency Heat light on at the same time. MALF - Malfunction. Malfunction indicates the heat pump system is sending a signal to the Malfunction Indicator on the thermostat terminal marked "L". It does not indicate a malfunction in the thermostat. The manufacturer of the Heat Pump system can determine the likely cause of malfunction indication on the thermostat.

Normally the blower will turn off a within a few minutes after the call for heat or cool. The blower running after the system shuts off may indicate (1) the thermostat is set to FAN ON, (2) the fan has been programmed to run at that time period or (3) something has damaged the thermostat or equipment. If the thermostat display indicates FAN ON, press the fan switch once to set it to FAN AUTO, meaning the fan will cycle only with the equipment. If the display indicates PRG FAN (Program Fan), sometime during programming, the FAN switch was pushed. To remove PRG FAN (Program Fan), check all of the programmed times and temperatures. When you encounter PRG FAN, press the FAN switch to remove it from that time period in the program. As a final test, switch the thermostat to OFF. Verify that Fan On or Fan Auto is not displayed. If the fan continues to run, you may want to contact your heating and cooling service person for assistance.

Adjustable Heating and Cooling Cycle Times (also called Anticipation ). Most Comfort-Set II thermostats have a feature that allows you to increase or decrease the cycle times in heating and cooling. This is useful if you think your cycle times are too long or too short. Comfort-Set II is adjusted by pressing SET CLOCK and SET DAY or ADV DAY at the same time and then using the Temp Up or Temp Down arrows to adjust the number displayed on the screen. The higher the number you select, the longer the cycle. The lower the number you select, the shorter the cycle. The range of adjustment for HEATING is from 2 to 40. The factory Preset is 5. The range of adjustment for COOLING is from 9 to 40. The factory Preset is 14. The cooling will not go below 9 because compressors require a longer cycle. The chart below shows how this adjustment range affects thermostat performance. Your thermostat is designed to cycle on and off in heating or cooling, keeping your building in an accurate temperature range. This maximizes your comfort by keeping the room temperature very close to the temperature you set. It is not unusual for your thermostat to be set for 70 and cycle on and off at 70 keeping you right on target. A note on older style thermostats; Anticipation on older style thermostats (mercury bulb or mechanical) used the current draw of the equipment to set the anticipation. Some heating and cooling equipment manufacturers still refer to setting the anticipator to the current draw of the equipment. This does not apply to your new digital thermostat. Right from the box your new thermostat will do an excellent job of keeping your building at an accurate temperature. The information above allows you to customize the performance of your digital thermostat to your requirements.

Typical terminals and functions for most single stage models (refer to specific installation instructions for your type or model number when wiring or installing): RH. . . . . . . . . . . .Power for heating. RC. . . . . . . . . . . .Power for cooling Y. . . . . . . . . . . . .Compressor W. . . . . . . . . . . . .Furnace G . . . . . . . . . . . . .Indoor Blower O . . . . . . . . . . . . .Powered constantly in cool B . . . . . . . . . . . . .Powered constantly in heat MV . . . . . . . . . . .Power for heating, millivolt system 6 . . . . . . . . . . . . .#6 terminal for SPDT zone valve.

To bypass the program and operate the thermostat manually (like a mechanical model) press SYSTEM button to select Heat or Cool (whichever your prefer) and press HOLD. Use the Temp Up or Temp Down buttons to set the thermostat on the temperature you want. The temperature setting you choose will be held until you manually change it using the Temp Up or Temp Down buttons. The thermostat will remain in the HOLD mode when you change temperature and maintain whatever temperature you set. If you decide to return to the program, press PROGRAM RUN to cancel the hold feature.

Battery (Flashing) on Display Battery flashing or blinking on the digital display indicates low batteries. If the batteries have recently been changed and the thermostat continues to indicate low batteries, use a pencil eraser to polish each of the battery contacts inside the back of the thermostat. Do not bend them up and down when polishing or you might break them. When complete, they should all be as shiny as a mirror. This will assure proper battery back-up, allow the backlight to work correctly and remove the flashing battery symbol from the screen. Battery (Solid) on Display The battery symbol (not blinking) indicates a loss of power (24 volts) from the heating and cooling equipment to the thermostat. Normally the heating and cooling do not operate when the battery indicator is on. If the battery indicator is on, check the fuses or breakers, make sure the furnace is switched on, and verify the blower compartment door is closed properly. The battery display is designed to indicate the thermostat is running on batteries, so replacing batteries has no effect on the indicator. See No Heat/No Cool for more information. Note: Some heat only systems (zoned systems) disconnect power from the thermostat during a normal heating cycle and display the battery symbol. Millivolt heating systems always indicate battery because they do not supply 24 volts to the thermostat.

The temperature display on a digital thermostat will normally read very accurately. If however, the heating and/or cooling system is oversized or undersized or the location of the thermostat is not ideal it can cause the temperature display for the room to read high or low. The Comfort-Set II series does not offer an adjustment to this room temperature reading.

For Comfort-Set II models press and release the buttons TIME FWD and TIME BACK at the same time to switch from Fahrenheit to Celsius or Celsius to Fahrenheit.

No Heat: With the system set to heat, when the set point temperature is raised or lowered past the room temperature, the thermostat will make a soft click sound within about 5 seconds. Usually the sound indicates correct thermostat operation. If the heat does not come on after raising the temperature and hearing the click, check the fuses or breakers, make sure the furnace is switched on, and verify the blower compartment door is closed properly. If no click sound is heard try resetting the thermostat as described below.

No Cool: Air conditioning systems usually include an outdoor compressor and an indoor blower. With the thermostat set to COOL and the temperature lowered below the room temperature by a couple of degrees, there can be up to a five minute delay before the thermostat activates the compressor and an indoor blower. If both the compressor and an indoor blower are running and the air is not cool it may indicate loss of refrigerant in the compressor. If the blower or compressor do not come on or do not shut off try the reset operation below.

Reset Operation: On Comfort-Set II models, removing the thermostat battery (or batteries) for five minutes will reset the thermostat. If a no heat or no cool condition persists after resetting the thermostat you may wish to contact your heating and cooling service person for assistance.

The thermostat will not allow a temperature in Heating set higher than the lowest Cooling temperature. This keeps the program from trying to bring on heat and cool at the same time. If you program your Cooling temperatures (all cooling temperatures) so they are 1 degree higher that the highest Heating temperature you intend to use when you switch to Heating there will be no conflict.

Comfort-Set II models retain the program for a short period of time (10-30 seconds) after power and batteries are removed. When power is restored, the thermostat will default to the factory settings. 90 Series models will retain the last program entered indefinitely without power or batteries.

Any time you wish to turn your system off, simply press SYSTEM button until the display shows OFF. This will not affect your thermostat's programming in any way. To turn the system back on, press SYSTEM button until HEAT, COOL, etc. is displayed. The system will begin operating according to the current thermostat program unless the thermostat is in the HOLD mode. See OPERATING YOUR THERMOSTAT in your Operating Guide.

Unless the thermostat appears to be damaged, it will follow the program that is in the memory. The most common reason a thermostat will appear not to be following the program is a programming error. Use the Quick Programming Guide from the Technical Help Section of our web site to check your program carefully. Verify that the AM or PM settings are correct for each period. Also verify that the Day of the week is set correctly. Some models have a SET DAY button and other models use the SET CLOCK button to synchronize the current day of the week. If the clock does not keep accurate time and the program defaults to the factory program, check or replace the batteries and clean the battery terminals as described in Question #4.

The display light in the 1F90 series is not a replaceable item. On single stage thermostats (1-heat/1-cool) the light uses battery power. If the light is not coming on, replace the batteries and/or clean the battery contacts inside the back of the thermostat. Use a pencil eraser to gently polish each of the battery contacts. Do not bend them up and down or they may break. When complete they should be as shiny as a mirror. This will assure proper battery back-up and allow the backlight to work correctly. The multi-stage and heat pump models obtain power for the light from the 24 volt transformer so if anything in the system interrupts power to the thermostat the light will not operate.

There is no need to select a time to stop a programming period. Starting a new programming period will stop the previous program period.