The usage portion of an electric bill includes a charge for the energy actually used (kWh). For many commercial customers, there also is a demand charge for the energy that the customer has the capacity to use and the electric company must have available. This additional fee is based on the peak demand, or highest amount of electricity used during the billing period.

Many commercial customers pay a demand charge to reflect the highest load for a period as short as 15 minutes during the course of an entire year. The PaceController is often set to reduce run time as much as 33%, and thus reducing load comparably. All customers with a demand charge have lower demand, but savings depend on the exact tariff, metering arrangements, and load details.

Cooling does not depend on the amount of time the compressor is running, but rather on the amount of refrigerant being moved. The PaceController moves more refrigerant per unit of energy-consuming compressor run time. The density of the refrigerant is greatest during the first few minutes of compressor run time, when the thermal expansion valve is wide open, so each compressor stroke can move more refrigerant.

In addition, the refrigerant continues to change state when the compressor is not in the run interval, and the circulating fan continues to distribute the cooled air. Third, the reduced running time and the circulating fan minimize frosting on the evaporation coils, supporting a more efficient heat transfer. Lastly, less icing means less energy is used in a defrost cycle.

Many large and sophisticated control systems are designed to prevent short-cycling or harm from poor electricity quality. Other systems that improve efficiency require expensive computer controls and cannot achieve the payback of the PaceController. The PaceController is focused on improving the efficiency of the compressor cycle (in the case of cooling or refrigeration systems) or the thermal energy source (in the case of heating systems). The PaceController can provide additional efficiencies and savings.

The PaceController uses virtually no power (usually less than 0.05 amperes). It is installed in the control lines of the controlled device and takes what power is used from the control lines, just like a thermostat.

In many heating and air-conditioning applications, the PaceController can improve user comfort. It minimizes overshooting of the temperature called for by the thermostat. It provides heated or cooled air more constantly at a more moderate temperature closer to the desired level.

The PaceController has no impact on appliance maintenance or operations. There are no known instances of the PaceController damaging a compressor or appliance.

The PaceController can contribute both to improved compressor performance and extended life in five different ways:

1. Prevents short-cycling

2. Reduces total compressor run-time, which also provides much of the savings

3. Improves lubrication efficiency during compressor operation by allowing more lubricating oil to be carried in the denser refrigerant gas

4. Allows the compressor electrical windings to cool during the enforced off cycle

5. Reduces coil frosting and freeze-over, and reduces or eliminates slugging

After the initial "off" period, a typical PaceController compressor cycle is:

ON CYCLE
Before being activated by the PaceController, gas is collecting on the suction side of the compressor. When the PaceController is activated, the compressor initiates its pumping process with an increasing density of refrigerant gas and encapsulated oil mist.

At the beginning of the cycle, the thermal expansion valve (TXV) is at its maximum opening. This maximum flow of dense gas fills each stroke of the compressor, providing the highest volumetric efficiency and also cooling of the compressor electrical windings.

As the compressor continues in the "ON" cycle, the TXV begins to restrict the volume of refrigerant entering the evaporator, due to the cooling effect sensed by the TXV temperature sensor, causing a reduction in the supply of refrigerant to the suction side of the compressor.

OFF CYCLE
After the preset "ON" cycle, the PaceController de-energizes the compressor control circuit for a few minutes. However, cooling and dehumidification continue as the fan moves air over the coils below the dew point. The following also occur:

• Condenser—condensation of hot gas to liquid continues
• Evaporator—air moves across the coil, dehumidifying and cooling continues
• System—all pressures balance
• Energy—none is consumed by the compressor until PaceController again allows the compressor control circuit to be energized.

REPEAT
At a preset interval, the PaceController again allows the compressor control circuit to energize and repeat this optimum cycle.

Compressors run most efficiently with a full load. The more dense the entry gas, the greater the load. The PaceController runs the compressor for the minimum "on" interval needed to cause gasification of the maximum quantity of liquid refrigerant per unit of compressor run time.

The rapid and effective change from liquid to gas results in maximizing the density of refrigerant gas entering each stroke of the compressor. Additionally, more lubricating oil is carried in the denser refrigerant gas, improving the operational life of the compressor.

The total effect is to capture the period of highest volumetric efficiency in each compression cycle, reducing energy consumption.

Synchronized cycling has many benefits.The total effect is to capture the period of highest volumetric efficiency in each compression cycle. Specfic benefits include:

• Reduced electric demand (kW) charges
  Demand charges for a load are typically based on the highest number of kW averaged over a 15- or 30-minute interval
• Reduced energy consumption (kWh)
  The HVACR equipment components are de-energized for a given interval
• Reduced compressor run time
  While also improving average volumetric efficiency and lubrication effectiveness, thus improving overall compressor life and reduced coil freeze-over

No. Very short run times that do not permit lubricant to circulate fully are called "short-cycling" and can be harmful to a compressor. The PaceController actually prevents short-cycling because it is always set for a run time longer than the minimum established by manufacturers to avoid harmful short-cycling.

Because the PaceController control sequence always begins with an "OFF" interval, the compressor or furnace will never be restarted immediately after it has been turned off, even if the thermostat says run.

The PaceController can be installed by a certified PaceController technician on many kinds of HVACR appliances that are in good working order.

Installation is quick and simple for any electrician or HVACR contractor, but installer certification assures that the PaceController is installed with proper settings in the right applications to assure both savings and full equipment operating performance.

PaceControls provides certification training through a 2-hour briefing and examination or an on-the-job certification. Topics covered include principles of operation, the installation manual, installation on the various major types of HVACR equipment, and building and system factors involved in setting up the PaceController.