After your meter has been installed and plugged into the power outlet, it will begin to calculate degree days.  The degree days will be slightly off the first day of operation due to the time of hook up and the temperature of the outside box when it is hooked up.  The following is a brief explanation and instruction of the use of each component of the inside unit.
 

    There is a 'heat only' counter on both the F-90 and F-90H.  This displays the degree days for your customers who use fuel oil, propane, or gas only for the purpose of operating their furnace.  These degree days are determined by the length of time that the outside unit is calling for heat.  The outside unit will call for heat more often the colder it gets outside, which means there will be more degree days accumulated.
    The F-90H also has a heat & hot water counter.  This takes the 'heat only' degree days and adds additional counts for the fuel used to operate the hot water heater.  The additional hot water degree days are determined by the length of time the outside unit is not calling for heat.  The more 'heat only' degree days that are calculated the less additional hot water degree days are added.  Once the outdoor temperature gets cold enough to produce more than 30 degree days on the heat only counter, only one or two extra counts will be added to the heat & hot water counter.  It is not unusual for the heat only and the heat & hot water counters to be the same when more than 30 degree days have been calculated.
    On each of the counters there is a button to the left of where the degree days are displayed.  This button is used to clear the degree days.  When this button is pushed the counter will return to a setting of zero.  Some software programs require you to set your degree day meter back to zero in the early fall. When the reset button is not being used slide it downward into the locked position.  With the button in this position, your meter cannot be accidentally set back to zero.
    If your counter is black with the reset button located underneath the displayed degree days, click HERE to find out how to reset your counter back to zero.
    The number of degree days will stay displayed on the counter if the meter is unplugged or if the power shuts off.  It will add one count to the heat & hot water counter everytime the meter loses power.
 

    Underneath and to the left of each counter, there is an 'add button' which is covered by a grey rubber boot.  The add button under the heat only counter will add one count to both counters on the F-90H.  It will add one count to the 'heat only' counter on the F-90.  The add button under the heat & hot water counter on the F-90H will add one count to the heat & hot water counter only.  The meter must be plugged into an outlet for these operations to be executed.  However, if you need to add counts to only your heat counter and not the hot water counter, you can accomplish this by simply pushing the add button under the heat only counter when the meter is unplugged from the outlet.  Other than sending the meter to our manufacturing facility, there is no other way of adding counts to the meter.  There is a period of operation in which no counts can be added to the meter.  If the add buttons do not add counts wait about 10 minutes and try again, or perform TEST 1 for 3-4 minutes.
 
 

    There are three indicator lights on the F-90H and two indicator lights on the F-90.  Both units have a red indicator light on the bottom right corner of the unit.  This light indicates that the unit has power being supplied to it.  Under the 'heat only' counter on both the F-90 & F-90H there is an orange indicator light.  This indicates when the unit is in the process of calculating a heat degree day.  The meter will not add a count every time the light comes on.
    Under the heat & hot water counter on the F-90H, there is an orange indicator light which indicates when the unit is in the process of calculating a hot water degree day.
    There will be a period of operation when neither of the orange indicator lights will be lit.