Residential HVAC service and installation contractors are witnessing a special time in this industry: the growing use of more-sophisticated diagnostics and controls in unitary systems. The benefits include reduced warranty claims, lower utility bills, improved comfort, and greater customer satisfaction.

Contractors who work on these systems will find they spend less time discovering the source of the system’s problem while their diagnostic accuracy goes up. This translates into fewer callbacks and, ultimately, spending less time replacing equipment that doesn’t have anything wrong with it.


Smart diagnostic and control systems based on Emerson Climate Technologies’ UltraTech™ and ComfortAlert™ diagnostics are being adapted by most unitary manufacturers, often but not always in high-end systems.

At the core of all these systems is a two-stage scroll compressor with compressor electronics that are compatible with high-end thermostat controls. The compressor electronics add system intelligence by using the scroll compressor as a sensor, with no additional sensors required. The resulting diagnostic information can be communicated to the thermostat to alert the homeowner to “call for service” when a severe system fault is detected.

The compressor and thermostat work together to ensure the cooling system meets the desired temperature and also controls humidity. When outdoor temperatures are lower than peak conditions, for instance, the thermostat tells the compressor and motor to operate at lower speeds. Air moves more slowly across the coils, and this removes more moisture from the air before it’s circulated in the home.

Improved homeowner comfort and lower energy consumption are direct benefits from systems using the UltraTech technology. The latest product developments are providing even more benefits for operating and servicing the installed product.


The newest developments allow system components to talk to each other. The contractor has instant access to the system’s fault history, which gives a more accurate picture of what has been going on.

Low-pressure and high-pressure trips, refrigerant charge, airflow, and more - today’s new unitary systems can, at the very least, point a technician in the right direction. They can also notify homeowners that a problem is severe enough to warrant shutting the system down. It won’t override the homeowner’s control, but the warnings are apparent.

Installations also become more foolproof thanks to the electronics that reach out and set up peripherals connected to the system.

The components all speak to each other using a common language. You are able to tap into the information they are sharing. A digital readout lets you know where faults are being detected. You take it from there.

For more information, click on the Emerson Climate Technologies logo above.