“If you’re the technician who has to return to a customer’s home because you forgot to plug in the disconnect (or flip the switch), you know the embarrassment,” Davis said. “Maybe you’re an owner or a manager and have to send someone back to make adjustments or corrections that should have been caught the first time.  Whatever the reason (or excuse), the time lost to make another trip without any additional revenue, sucks.”  

Randy Speights, senior technical product manager at Lennox Commercial, said most heat pump callbacks stem from installation and setup mistakes, not equipment defects.  

Common culprits include incorrect sizing, poor airflow, improper refrigerant charge, and thermostat or control configuration errors.   

“For example, a furnace delivers the same amount of heat to the space regardless of if the outside air conditions are warm or cold,” Speights said. “A heat pump can range a bit on its delivery depending on outside conditions, so technicians must do a bit of diligence to understand when a heat pump should run or when an auxiliary heat source may need to operate to provide supplemental or emergency heating.”  

If that transition, or switchover point, isn’t properly set, a customer may not be maximizing their system's performance, and callbacks can follow. But, when the system is properly designed, installed, and commissioned, modern heat pumps are extremely reliable.  

The folks at TCL also identified two common callback triggers: refrigerant charge and thermostat setup. Installers may undercharge the system, skip the step entirely, or miswire the thermostat.  

Load Calculations and Equipment Sizing  

Improper load calculations and equipment sizing remain major callback drivers, especially in residential work.   

“This is a common problem,” Rodrigo V. C. Teixeira, general manager – TCL Comfort & HVAC, said. “However, most companies do troubleshoot and make corrections without having to call for support. It’s difficult to give statistical data, but it is a topic I touch on when I am conducting a seminar on our equipment in an attempt to avoid this problem, which might be overlooked.”  

Speights said he’s seen data to support this claim.  

“There are credible studies that exist which find 30-40% of residential applications are likely to be improperly sized,” Speights said. “I'd suggest that the percentage of improper sizing is lower for commercial, but still a concern, and especially as spaces tend to change their intended design usage over the life of the space, such as may happen in a tenant finish out.”  

When dealing with comfort complaints, if the system is operating per the manufacturer design, Speights says equipment selection is usually the first thing a contractor should review.   

Commissioning Steps That Count  

When it comes to commissioning, several errors show up repeatedly: failing to verify airflow, refrigerant charge, thermostat configuration, and defrost operation.  

“Because heat pumps are more affected by environmental conditions, then say a furnace, improper airflow and the configuration of controls can noticeably affect performance,” Speights said. “A proper refrigerant charge is also key, so training technicians on how to check and optimize refrigerant charge in both a heating and cooling season should be a priority.”  

Manufacturers provide instruction on how to properly charge a system in various outdoor temperatures, he added, as well as guidance on checking defrost operation. If properly commissioned, heat pumps should operate reliably with the same reliability as a cooling-only unit.  

TCL commonly sees three commissioning mistakes that lead to callbacks:  

• airflow not being verified by recording static pressure and properly setting blower CFM;  

• refrigerant not being weighed in, either because the installer lacks the right tools or did not read the manual; and  

• thermostats not being configured for heat because the installer never tested the equipment in heating mode, especially in warmer regions.  

Cold Climate Issues  

Cold-weather operation brings another layer of complexity. Speights said two issues stand out: reduced capacity at lower outdoor temperatures and improper switchover settings for auxiliary or secondary heat.   

“This is related to the proper sizing and commissioning of equipment, as noted before. If a heat pump isn't sized to provide the amount of heat needed to satisfy an occupant's demand at the outside design temperatures for that area, then there will be complaints - either temperature complaints or concerns about energy consumption,”   

“At some point, on conventional systems, it may be cheaper to run a secondary heat source where the heat pump may not be able to satisfy the need; this is where the proper setting of the switchover point in controls has a significant impact on comfort and to one's wallet,” Speights said.  

It’s also important to note that many variable-speed heat pumps efficiently provide more capacity from the mechanical heating cycle at lower temperatures and may not need additional heat.  

Tips on Eliminating Callbacks  

When asked if there were any commissioning steps contractors could follow that would eliminate the largest percentage of callbacks if performed consistently, Speights suggests checking airflow, ensuring that there is the proper charge in the system, and paying attention to the switch-over temp.   

Here are three more tips from TCL:  

• Weighing the refrigerant for accuracy and performance when needed.  

• Configure the thermostat and wiring the system correctly.  

• Properly set up system dip switches in high efficient equipment, such as variable speed blowers and inverter systems, for maximum performance.  

Davis’ Three Categories  

Davis broke callback causes into three categories: rushed, grifter, and ignorant.  

Rushed is the easiest to recognize. When managers or dispatchers push technicians to squeeze in one more call, help with another install, or move faster during peak weather, quality suffers. Davis said companies have to leave enough time to diagnose the system, identify the problem, document findings, present options, and verify performance after repairs.  

Otherwise, the result is an incomplete diagnosis and half-finished solutions: add refrigerant and go, replace a fan motor, and move on. Those shortcuts create callbacks because they treat symptoms instead of the whole system.  

Grifter is harsher, but Davis said it is real. This is the technician who knows what to do and simply chooses not to do it, whether out of laziness, disengagement, or worse. They may assume they will be gone before the system trips on head pressure or the new motor burns up. In those cases, Davis said there is no easy cure, though better digital tools and mobile apps can make poor workmanship easier to spot.  

Ignorant, Davis stressed, does not have to be an insult. Sometimes it just means a technician is new and still learning. Other times, it means someone has been in the trade for 20 years but is still relying on rules of thumb instead of a deeper understanding.  

That problem is fixable with training, curiosity, and better information. Davis urged contractors to read the manual, ask questions, use trusted training resources, and look beyond a single measurement or tool. A digital manifold gauge may be useful, but it cannot tell the whole story about fan performance, airflow, or entering and leaving air conditions.  

That is where newer digital tools can help, by pulling together data from multiple instruments and giving technicians a more complete picture of system operation. Without that full picture, a contractor may blame a “bad” component when the real issue is undersized ductwork, improper airflow, or another system-level problem.  

The takeaway is simple, Davis said: Get good. Read, ask questions, stay curious, be patient, take the time, and look at the whole system.