One of the best approaches to re-conditioning a
building after night set-back is with the use of an optimum-
time start device. This microprocessor-based thermostat
compares the outside and inside temperatures
along with the desired setpoint during the operating
cycle. It determines how long it will take to re-condition
the building to the setpoint based on previous data and
turns the system on at the appropriate time to reach the
setpoint temperature just in time. Since time clocks must
be set to turn the system on with adequate time to re-condition
the building on even the coldest morning, the optimum-
time start device can save more than half of the
warm-up time on days when the outdoor ambient temperature
is moderate.