These temperature and resistance values are used to solve for coefficients a, b, and c in the SH-H equation (Equation 13), using a least-squares fit algorithm. Figure 10 shows the residuals (the observable estimates of the unobservable statistical error) when applying the resulting SH-H equation to a thermistor. proportional-integral controlled chiller/heater system controlled the temperature, using thermistor A1 as the feedback in the control loop. When compared to the set-point temperature, errors in temperature A1 should be the smallest and this was indeed the case, as we see in Figure 9.
As warmer weather taxes aging air-conditioning systems, the decision whether to repair an older rooftop unit or replace it with a newer, higher efficiency system may loom large for some commercial property owners. Most light-commercial HVAC products are designed for a life expectancy of 15 to 20 years.
If your air conditioner is between 10-15 years old, it may be more cost efficient to replace the unit, especially if your unit is no longer under warranty. If your unit is in need of frequent repairs, the repairs may end up costing you more than a new unit in the long run.he average air conditioning system will last between 10-15 years. Even if your air conditioning system has not stopped working completely, it could be worth looking into replacing your older system for a new system that is more energy efficient.