Retrofitting

There are numerous applications for two levels of controls. One example is a large room served by two air handlers. Instead of having both controlled by a single thermostat (which may resort to short- cycling […]

Mechanical designers traditionally have modulated airflow through VAV systems with inlet vanes. The fan motor operates at a constant speed, while the vanes open and close to maintain a constant static pressure at the fan […]

A common humidity problem of direct-expansion systems can be resolved by having two coils in the system on separate refrigerant circuits. The system is controlled by a two-stage thermostat. One coil is activated first. If […]

The ultimate objective of any serious energy-conservation program is a central, computer-automated electronic controls system. This integrated system of remote sensors and control devices permits the optimum use of energy in all areas while simultaneously […]

Commercial installations often have two-stage thermostats that automatically change over from heating to cooling. Typically there ’s a 10 or 15°F range that is fixed into the controls, so that if the space temperature drops […]