bro, for pure DI unit, u can't juz account for the cost in this way. u left out your P.U.B bills for the water......... how much does 500L of water cost?
how sure r u?
1) some chiller thermostat controllers do hv the previous preset temp setting in them even if u shut off the power. at least mine does.
2) most chillers do not built in timer control, but they do hv time delay functions of up to 30 mins. at least mine does.
use a good old alcohol or mercury thermometer to verify ur temp readings.
is there any way the hailea chiller thermostat can be calibrated? if not, u might wanna get an external thermostat controller.
may i know what good does it does to hv ur chiller on timer control? by the time ur chiller cuts out for a few hrs using timer control, ur temp wld hv fluactuated way out of limits, considering the high ambient temp nowadays.