What You'll Learn

• Why heat pumps in cooling mode use the same AC Install workflow, and when to switch to the Heat Pump Heating workflow
• How to select the correct workflow for a heat pump installation based on the mode you are testing
• How the refrigeration cycle reverses in heating mode and what that means for probe placement
• Where superheat and subcooling are measured in heating mode vs. cooling mode
• How to profile a heat pump system correctly, including heat type and defrost considerations
• How to handle defrost cycles, auxiliary heat, and variable-speed operation during testing
• What the diagnostic screens show differently in heat pump heating mode

What You'll Need

• Device: iPhone (iOS 15+) or Android phone/tablet (Android 10+) with measureQuick installed
• App version: v3.5 or later
• Account: Active measureQuick account with Premier Services (see Subscription Activation)
• Smart tools: Minimum 9 probes connected for a full cooling or heating diagnostic (see Bluetooth Pairing Basics, Fieldpiece Probe Pairing)
• Equipment: Heat pump system (split or package) accessible for installation commissioning
• Knowledge: Familiarity with the A/C Installation Workflow (see G1); understanding of superheat and subcooling (see E3); heat pump heating mode probe placement (see F6)
• Time: 15 minutes to read; 30-45 minutes for a full heat pump installation test in the field

The Key Concept: One System, Two Workflows

A heat pump is an air conditioning system with a reversing valve. In cooling mode, it operates identically to a standard A/C system. In heating mode, the reversing valve switches the direction of refrigerant flow, and the roles of the indoor and outdoor coils swap.

This means measureQuick uses two different workflows for heat pumps depending on the mode:

If you are commissioning a new heat pump installation, you will typically run both workflows: AC Install for cooling mode performance, then Heat Pump Heating for heating mode performance.

Heat pump commissioning demands more technical knowledge than standard A/C commissioning because you must verify performance in both modes. DR Richardson (Owner, Elephant Energy) describes measureQuick as providing "a data-driven methodology and process to ensure we've done that commissioning checklist," noting that paper-based checklists are not data-connected. With heat pump market share at 47% of installations in measureQuick's 2025 data, this workflow is increasingly common.

Step-by-Step Guide

Step 1: Create a Project

Open measureQuick and create a new project for this installation.

1. Tap the + button on the home screen or navigate to Projects.
2. Enter the job details: customer name, address, date.
3. Tap Save to create the project.

See Creating Projects for detailed project setup instructions.

New project screen with customer name, address, and date fields

Step 2: Start the Cooling Mode Test (AC Install Workflow)

For a new heat pump installation, start with cooling mode. Set the thermostat to call for cooling and allow the system to run.

1. Inside your project, tap New Test.
2. Select AC Install as the workflow type.
3. The Guided Workflow opens with the Indoor and Outdoor checklists.

This is the same workflow described in A/C Installation Workflow. The cooling mode test for a heat pump is identical to an A/C installation test. Follow the G1 procedure for:

• Indoor probe placement (return air, supply air, static pressure)
• Outdoor probe placement (suction line, liquid line, discharge line, outdoor ambient)
• System profiling (AI Profiler or manual entry)
• Running the test and waiting for stabilization
• Saving the test

Tip: When profiling the equipment, make sure the system type is set to Heat Pump, not Air Conditioner. The equipment type does not change the cooling mode diagnostics, but it ensures the project record correctly identifies this as a heat pump system.

Workflow selection screen showing cooling project types including A/C or Heat Pump Installation

Step 3: Save the Cooling Mode Test

Once the system stabilizes and all diagnostics are evaluated:

1. Review the Diagnostics screen for pass/fail results.
2. Tap Save Test In to capture the cooling mode snapshot.

This is your "test in" for the cooling mode. See Save Test In / Save Test Out for details on the snapshot process.

Diagnostics screen showing cooling mode results with Save Test In button

Step 4: Switch to Heating Mode

Now test the heating mode. Switch the thermostat from cooling to heating. Allow the system to cycle off cooling and start the heating cycle.

Before starting the heating mode test:

1. Wait for the changeover. The system needs time to switch modes. The reversing valve actuates, and refrigerant flow direction changes. Allow 5-10 minutes for the system to reach steady heating operation.
2. Confirm the outdoor unit is in heating mode. The outdoor fan runs, and you can feel cold air exhausting from the outdoor unit (it is now absorbing heat from outdoor air). The indoor unit should be delivering warm air.

Step 5: Start the Heat Pump Heating Workflow

1. Inside the same project, tap New Test.
2. Select Heat Pump Heating as the workflow type.
3. The Guided Workflow opens with the Indoor and Outdoor checklists, configured for heating mode.

The Heat Pump Heating workflow looks similar to the AC Install workflow but with critical differences in how it interprets your measurements.

Workflow selection screen showing Heat Pump Heating Test option in the Heating Projects section

Step 6: Profile the System for Heating Mode

If you already profiled the equipment during the cooling mode test, the app carries forward the equipment identification (manufacturer, model, serial, refrigerant, tonnage). You still need to confirm or set heating-specific profile fields:

1. Navigate to the System Profile screen within the heating workflow.
2. Confirm the Heat Type is set correctly:
   • Heat Pump for a standard heat pump
   • Dual Fuel if the system has a gas furnace backup
3. Confirm the Refrigerant matches the cooling mode test (it should be the same system).
4. Verify the Metering Device setting. In heating mode, the metering device that matters is the one at the outdoor coil (which is now the evaporator). Some systems use a TXV at the outdoor coil; others use a piston/fixed orifice. Check the installation documentation.

Tip: The outdoor metering device may differ from the indoor metering device. In cooling mode, the indoor metering device controls expansion. In heating mode, the outdoor metering device controls expansion. The system profile for heating mode should reflect the outdoor metering device.

Step 7: Understand the Reversed Cycle

This is where heat pump testing differs from A/C testing. In heating mode, the refrigeration cycle reverses:

What this means for measurements:

• Superheat is now measured at the outdoor unit (the evaporator in heating mode). The suction line from the outdoor coil carries superheated gas back to the compressor.
• Subcooling is now measured at the indoor unit (the condenser in heating mode). The liquid line from the indoor coil carries subcooled liquid to the outdoor metering device.

measureQuick handles this reversal automatically when you select the Heat Pump Heating workflow. The app knows which probes correspond to evaporator-side and condenser-side measurements based on the workflow selection.

[Diagram] Heat pump refrigerant cycle in heating mode. The outdoor coil acts as the evaporator (absorbing heat from outdoor air), and the indoor coil acts as the condenser (releasing heat into the home). Superheat is measured at the outdoor unit (suction line leaving the outdoor coil), and subcooling is measured at the indoor unit (liquid line leaving the indoor coil). The reversing valve redirects refrigerant flow so that every line's thermal role is swapped compared to cooling mode.

Step 8: Place Probes for Heating Mode

Probe placement changes in heating mode because the coil roles are reversed. See Heat Pump Heating Mode Probes for detailed placement instructions. The summary:

Outdoor unit (now the evaporator):

• Suction line temperature - on the suction line leaving the outdoor coil, before it enters the compressor. This is the "true suction" in heating mode.
• Suction pressure - measures evaporating pressure at the outdoor unit.
• Outdoor ambient temperature - same location as cooling mode.

Indoor unit (now the condenser):

• Liquid line temperature - on the liquid line leaving the indoor coil.
• Discharge/liquid pressure - measures condensing pressure at the indoor side.
• Supply air temperature - in the supply register or plenum.
• Return air temperature - in the return plenum.

Static pressure probes remain in the same locations as cooling mode (return side and supply side of the air handler).

[Diagram] Heat pump heating mode probe placement. Outdoor unit (evaporator side): suction line temp clamp on the line leaving the outdoor coil, suction pressure at the outdoor service port, outdoor ambient sensor 3-5 ft from unit. Indoor unit (condenser side): liquid line temp clamp on the line leaving the indoor coil, discharge/liquid pressure at the indoor side, supply air temp in the supply plenum, return air temp in the return plenum. Static pressure probes remain in the same duct locations as cooling mode.

Tip: If you left probes in place from the cooling mode test, you may need to physically move the suction line probe. In cooling mode, the suction line is at the indoor coil. In heating mode, the suction line is at the outdoor coil. The liquid line probe may also need to move depending on your setup.

Step 9: Run Through the Heating Mode Checklist

The Heat Pump Heating workflow presents a guided checklist similar to the AC Install workflow. Work through each section:

1. Indoor checklist: Verify return and supply air temperatures, static pressure readings, and air handler operation.
2. Outdoor checklist: Verify suction line temperature, outdoor ambient temperature, and pressure readings at the outdoor unit.
3. System profile confirmation: The app prompts you to confirm the heating profile settings.
4. Diagnostics evaluation: The app calculates superheat (at the outdoor evaporator), subcooling (at the indoor condenser), airflow, static pressure, and other parameters.

Wait for the system to stabilize before evaluating diagnostics. Heating mode stabilization typically takes 10-15 minutes of continuous operation. As the Part 4 video demonstrates, use the stabilization wait productively: "pay attention to during this test while we wait for the system to stabilize, let's go ahead and get our meter connected to Bluetooth." See System Stabilization.

Step 10: Review Heating Mode Diagnostics

The Diagnostics screen in heating mode displays the same pass/fail indicators as cooling mode, but the underlying calculations reflect the reversed cycle:

Review each diagnostic. Tap any indicator to open the detail screen and see the measured value, target, and acceptable range.

Step 11: Save the Heating Mode Test

Once the system has stabilized and you have reviewed all diagnostics:

1. Tap Save Test In to capture the heating mode snapshot.
2. The project now contains two tests: one for cooling mode and one for heating mode.

For a new installation, both tests together document the full commissioning of the heat pump in both operating modes.

Project view showing two saved tests, one cooling mode and one heating mode

Handling Defrost Cycles

Heat pumps in heating mode periodically run defrost cycles to melt ice that accumulates on the outdoor coil. During defrost, the system temporarily switches back to cooling mode (the reversing valve actuates) to send hot gas through the outdoor coil.

What happens during defrost:

• The outdoor fan typically stops.
• Refrigerant flow reverses briefly.
• Readings become erratic: pressures swing, temperatures spike, and diagnostic indicators flash.
• The cycle lasts 2-10 minutes depending on ice buildup and ambient conditions.

Do not save a test during a defrost cycle. Wait for defrost to complete and the system to return to steady heating operation. You will know defrost is over when:

• The outdoor fan restarts.
• Pressures return to normal heating mode levels.
• Supply air temperature stabilizes at the expected heating output.

Allow an additional 5-10 minutes after defrost ends before evaluating diagnostics or saving the test.

Variable-Speed Heat Pumps

Variable-speed (inverter-driven) heat pumps adjust compressor speed to match the heating load. This affects testing:

• Capacity varies. The system may not run at full capacity during mild weather. Superheat and subcooling values at part load differ from full-load design conditions.
• Test mode. Some manufacturers provide a test mode that forces the compressor to run at a specific speed (typically full capacity). Check the manufacturer's installation manual for test mode activation procedures. If available, use test mode for commissioning.
• Stabilization takes longer. Variable-speed systems may take 15-20 minutes or more to reach steady state at a given speed.
• Profiling. See Variable Speed Equipment for profiling instructions specific to inverter-driven equipment.

Tip: If the system does not have a test mode and outdoor conditions are mild, the compressor may run at minimum speed. Document the operating conditions (outdoor temp, compressor speed if displayed) alongside the test results. A commissioning test at part load is still valuable; note the conditions in the project.

Auxiliary and Emergency Heat

Heat pump systems often include auxiliary heat strips (electric resistance) or a backup furnace (dual fuel). These activate when:

• Outdoor temperature drops below the system's balance point (typically 25-35 F).
• The thermostat calls for supplemental heat.
• The system is in emergency heat mode (compressor locked out).

During a heat pump heating mode test:

• Auxiliary heat ON: Supply air temperature may be higher than expected from the heat pump alone. The heat strips add heat to the airflow. If you are testing heat pump performance specifically, disable auxiliary heat at the thermostat during the test.
• Emergency heat mode: The compressor is off and only the heat strips run. measureQuick cannot evaluate refrigerant diagnostics (superheat, subcooling) without compressor operation. Switch the thermostat out of emergency heat mode for commissioning.

Transcript Insights

Jim Bergmann describes the heat pump heating workflow process in his Part 4 walkthrough: "workflows for heat pump heating operation, not the non-invasive test, rather the gauge-up test, so we're going to be gauging up... installed the system in heat pump heating mode, we can simply do a test, but every OEM will tell you that the proper way to commission" requires the full gauge-up approach.

On using wait time productively during stabilization: "pay attention to during this test while we wait for the system to stabilize, let's go ahead and get our meter connected to Bluetooth." This approach - completing ancillary tasks during the stabilization period - keeps the workflow efficient without rushing measurements.

From the Heat Pump Commissioning Standards discussion, Jim notes the growing importance of this workflow: "your homeowner decides they want to put a heat pump in, or you talk them into a heat pump, even if they have a heat pump, let's say they have a heat pump..." With heat pump market share at 47% of installations in measureQuick's 2025 data, proper commissioning in both modes is a baseline skill.

Customer Insights

• DR Richardson (Owner, Elephant Energy) describes measureQuick as providing "a data-driven methodology and process to ensure we've done that commissioning checklist," noting that paper-based checklists are not data-connected. This is particularly relevant for heat pump installations where both cooling and heating mode results must be documented.

• Michael Housh (Owner, Housh Home Energy): "Our new installation callbacks have been reduced. We're not having to go back later to resolve issues." He credits the guided workflow structure with ensuring no commissioning steps are skipped, which is especially important when commissioning both modes on a heat pump.

• Tevis DesChamp (Owner, Fire and Ice Refrigeration): "Two new guys did about 50 calls their first month with no callbacks and eight or nine five-star reviews." His company uses measureQuick to get entry-level technicians running heat pump service calls within three to four months.

Video Walkthrough

• YouTube: (13 min). The primary reference for this article. Walks through the heat pump heating gauge-up test workflow from start to finish, including airflow adjustments after commissioning, probe deployment, and stabilization. Covers both the non-invasive and full gauge-up test approaches, noting that "every OEM will tell you that the proper way to commission" requires the full gauge-up test

• YouTube: (80 min, HVAC Design Partners). In-depth discussion on heat pump commissioning standards, including real-world examples of TrueFlow testing on existing systems and the business case for proper commissioning

• YouTube: (21,950 views, 1:41). Short demonstration of where to place probes when the heat pump is running in heating mode

• YouTube: (1,390 views, 8 min). Covers non-invasive and full diagnostic approaches for heat pump heating mode

• YouTube: (14 min). Detailed walkthrough of all heating workflows in measureQuick, including heat pump heating mode

• YouTube: (9,324 views, 18:40). Covers variable-speed compressor testing, profiling, and diagnostic interpretation

• YouTube: (4:00). Demonstrates how to start a heat pump heating and cooling project from the cloud, including loading existing equipment profiles and saving data. Jim Bergmann: "I'm going to tap on AC heat pump heating and cooling and I'm just going to start this from the cloud."

Tips & Common Issues

I selected AC Install for a heat pump in heating mode

The AC Install workflow assumes the outdoor unit is the condenser and the indoor unit is the evaporator. In heating mode, those roles are reversed. If you run AC Install while the system is in heating mode, the diagnostic calculations will be wrong: superheat and subcooling will be evaluated at the wrong measurement points, and the pass/fail results will not reflect actual system performance.

Switch to the Heat Pump Heating workflow. You do not need to re-profile the equipment; start a new test with the correct workflow selection.

Superheat and subcooling seem swapped compared to cooling mode

They are. In cooling mode, superheat is measured indoors (evaporator side) and subcooling is measured outdoors (condenser side). In heating mode, those locations reverse. If you are seeing values that seem backward, confirm you selected the correct workflow (Heat Pump Heating, not AC Install) and that your probes are in the correct heating mode positions.

Supply air temperature is low in heating mode

Check outdoor ambient temperature. Heat pump heating output decreases as outdoor temperature drops. At 40 F outdoor, a heat pump may deliver 100-110 F supply air. At 20 F outdoor, supply air may drop to 85-95 F. This is normal heat pump behavior; the system extracts less heat from colder outdoor air.

If supply air is unusually cold (below 80 F) and the system has been running for 15+ minutes, check for:

• Incorrect refrigerant charge (run the diagnostics)
• Restricted airflow (check TESP)
• Defrost cycle in progress (wait for it to complete)
• Reversing valve stuck in cooling mode (outdoor coil will feel warm instead of cold)

The system keeps going into defrost during testing

Frequent defrost cycles indicate heavy ice buildup on the outdoor coil. Possible causes: low refrigerant charge, dirty outdoor coil, faulty defrost control, or testing at high humidity with near-freezing outdoor temperatures. Wait for each defrost cycle to complete before taking readings. If defrost cycles are more frequent than every 30 minutes, document this as a finding.

How do I test both modes on the same visit?

1. Run the cooling mode test first (AC Install workflow). Save the test.
2. Switch the thermostat to heating mode.
3. Wait 5-10 minutes for the changeover.
4. Start a new test using the Heat Pump Heating workflow. Save the test.
5. Both tests live under the same project.

If outdoor conditions are too cold for cooling mode testing (below 60 F outdoor), defer the cooling mode test to a warmer day. If outdoor conditions are too warm for heating mode testing (above 65 F outdoor), the heat pump may not sustain heating operation long enough for a valid test. Document what you can and note the outdoor conditions.

Metering device selection for heating mode

In cooling mode, the metering device at the indoor coil (TXV or piston) determines the primary charge indicator. In heating mode, the metering device at the outdoor coil determines the primary charge indicator. Some systems have a TXV indoors and a piston outdoors, or vice versa. Check the manufacturer's installation documentation and set the heating mode profile accordingly.

The outdoor unit sounds different in heating mode

This is normal. In heating mode, the outdoor unit is the evaporator. Suction pressure is lower than in cooling mode (the system is absorbing heat from potentially cold air), and compressor operation sounds different at lower suction pressures. Louder or higher-pitched compressor noise in heating mode does not necessarily indicate a problem.

Vitals score requires 9+ physical probes

The Vitals score (0-100 system quality rating) requires 9 or more physical probe channels connected for cooling and heating modes. If fewer than 9 physical probes are connected, the Vitals score will not calculate. Verify your probe count on the measurement screen before expecting a Vitals result. See Understanding Diagnostic Screens for details on the Vitals score requirements.

Related Articles

Prerequisites (complete these first):

• A/C Installation Workflow
• AI System Profiler or Manual Equipment Profile
• Outdoor Probe Placement
• Heat Pump Heating Mode Probes
• Superheat & Subcooling

Follow-up articles (next steps after this one):

• Heat Pump Service Workflow
• Save Test In / Save Test Out
• System Stabilization

Related in the same domain:

• Variable Speed Equipment

Need Help?

If you get stuck or this article does not answer your question:

• Check the Related Articles section above
• Contact measureQuick support: support@measurequick.com