Thermostat Calling for Heat but Getting AC? Heat Pump Troubleshooting

Thermostat Calling for Heat but Getting AC? Check Your Heat Pump Settings!

When the seasons change, one of the most common troubleshooting calls we receive at ECOJAY is surprisingly simple: "My thermostat is calling for heat, but my air conditioner is running!"

This problem often appears during the first cold days of fall, when homeowners switch their HVAC systems from cooling to heating for the first time in months.

The good news? In many cases, nothing is actually broken. The problem is simply a configuration mismatch between the thermostat, HVAC zone control panel, and heat pump equipment.

Let's explain why this happens and how to fix it.

Understanding How a Heat Pump Switches Between Heating and Cooling

Unlike a conventional furnace and air conditioner, a heat pump uses the same refrigeration system to provide both heating and cooling.

To switch between these two modes, a heat pump uses a component called a reversing valve.

The reversing valve changes the direction of refrigerant flow, allowing the system to either heat or cool your home.

Here's where things get interesting: Not all heat pumps use the same reversing valve logic!

Heat pumps typically use one of two configurations:

• O (energized in cooling): The reversing valve receives 24VAC during cooling operation. This is the most common configuration used by residential heat pump manufacturers.

• B (energized in heating): The reversing valve receives 24VAC during heating operation. This configuration is used by certain manufacturers, most notably Rheem and Ruud.

Both methods accomplish the same thing, but they operate in opposite ways.

If your HVAC controls are configured for the wrong type, your heat pump may operate in cooling mode when heating is requested, or vice versa.

Why HVAC Zoning Systems Add Another Configuration Step

In a traditional single-thermostat installation, the thermostat controls the heat pump directly.

However, in a zoned HVAC system, the zone control panel sits between the thermostats and the HVAC equipment.

That means three components must be configured correctly:

1. The thermostat: Must be configured for the appropriate system type, such as a conventional furnace/AC or a heat pump, and the correct O/B setting when applicable.

2. The zone control panel: Must recognize the thermostat's heating and cooling signals and translate them into the correct equipment outputs.

3. The HVAC equipment: The heat pump's reversing valve operation must match the configuration of the zone control panel.

If any of these settings are incorrect, the system may run in the opposite mode from what the thermostat requests.

For example, a heat pump that requires an O signal for cooling could mistakenly receive that signal during a heating call if the zone control panel is configured for B operation.

The result? Your thermostat says HEAT, but your system delivers COOL air!

How to Troubleshoot the Problem

Before assuming that your heat pump, thermostat, or zone controller is defective, check these common configuration issues.

Step 1: Verify the Thermostat Configuration

Enter the thermostat's installer setup menu and confirm that the equipment type is configured correctly.

If the thermostat is connected to a zone control panel, follow the zone panel manufacturer's instructions for selecting the thermostat type. Some zoning systems require thermostats to be configured as conventional heating/cooling thermostats, even when the equipment itself is a heat pump.

Step 2: Check the Zone Control Panel Settings

Verify that the zone control panel is configured for the actual HVAC equipment.

For heat pump systems, confirm the reversing valve setting (DIP SWITCH #2):

• O = Reversing valve energized during cooling

• B = Reversing valve energized during heating

Also verify that the zone panel's thermostat configuration matches the type of signals being sent by each thermostat.

Step 3: Verify the Heat Pump Equipment Requirements

Consult the installation documentation for your particular heat pump.

While O operation is more common, some manufacturers use B operation. Never assume the correct setting based solely on the thermostat's default configuration.

Step 4: Test Heating and Cooling

After confirming the settings, test the system in both heating and cooling modes.

Allow time for the equipment's built-in compressor protection delays before evaluating operation.

Confirm that the equipment actually produces heating when requested and cooling when requested.

If the system still operates incorrectly, a qualified HVAC technician can check the thermostat signals, zone panel outputs, and reversing valve circuit.

A Special Note for SmartZone Owners

ECOJAY SmartZone controllers are designed to work with conventional heating/cooling systems and heat pump equipment, including systems with O or B reversing valve operation.

When troubleshooting a SmartZone installation, it's important to verify both the thermostat configuration and the equipment configuration on the SmartZone panel.

Remember that the thermostat type and the HVAC equipment type are not necessarily the same setting. A heat pump installation may use conventional thermostat signaling, depending on the zone panel configuration.

Before changing wiring or replacing equipment, review your SmartZone installation guide and confirm the correct setup.

The Bottom Line: Check the Settings Before Replacing Parts!

When your thermostat calls for heat but the system produces cooling, the problem may be nothing more than an incorrect thermostat or zone controller setting.

This is particularly common during seasonal changeovers, when a configuration problem that went unnoticed during summer cooling suddenly becomes obvious.

Understanding the difference between O and B reversing valve operation—and ensuring your thermostat, zoning controller, and heat pump are configured to work together—can save time, frustration, and unnecessary service calls.

Need help with your SmartZone installation?

Visit ZoningSupply.com for SmartZone zoning controllers, installation resources, and HVAC zoning accessories.

ECOJAY has been developing innovative HVAC zoning solutions for more than 20 years, with a focus on making zoning easier to install, configure, and troubleshoot.

Heat Pumps Have Changed the HVAC Industry Forever

—Here's Why Zone Control Matters More Than Ever

For decades, the standard residential HVAC system in much of the United States followed a familiar formula: a natural gas furnace for heating and a central air conditioner for cooling. This "gas/electric" combination became the default choice for millions of homes because it was reliable, relatively inexpensive to install, and well suited to many climates.

Today, however, the market is changing rapidly.

Heat pumps are no longer a niche product reserved for mild climates. They have become one of the fastest-growing segments of the HVAC industry, and recent shipment data shows just how significant that shift has become. According to the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), manufacturers shipped approximately 3.6 million air-source heat pumps in 2025 compared to roughly 3.2 million gas furnaces, meaning heat pumps outsold gas furnaces by about 12%. While heat pumps first overtook gas furnace shipments earlier this decade, the gap continues to widen as technology improves and consumer demand grows.

For homeowners, contractors, and HVAC professionals, this isn't simply a change in equipment—it represents a shift in how homes are designed, controlled, and optimized.

One technology that becomes increasingly valuable alongside modern heat pumps is zoning.

Why Heat Pumps Are Winning

Several factors have driven the rapid adoption of heat pumps throughout the United States.

1. One System for Heating and Cooling

Unlike a traditional furnace that only provides heat, a heat pump performs both heating and cooling.

During summer it functions just like an air conditioner. During winter it reverses the refrigeration cycle, extracting heat from the outdoor air—even when temperatures are well below freezing—and delivering it inside the home.

Homeowners appreciate having one integrated comfort system instead of separate heating and cooling equipment.

2. Dramatic Efficiency Improvements

The biggest misconception about heat pumps is that they only work in warm climates.

That may have been true twenty years ago.

Modern inverter-driven compressors, improved refrigerants, and advanced defrost controls have transformed today's heat pumps. Many premium systems now maintain excellent performance well below 0°F, making them practical across much of the United States.

Because heat pumps move heat rather than create it through combustion or electric resistance, they can deliver two to four units of heat for every unit of electricity consumed, making them remarkably efficient under many operating conditions.

3. Lower Operating Costs

In many regions, homeowners can reduce annual heating costs by switching from electric resistance heat or older HVAC equipment to a modern heat pump.

Actual savings depend on:

• Local utility rates

• Winter temperatures

• Home insulation

• Equipment sizing

• Installation quality

But overall, rising efficiency has made heat pumps an attractive long-term investment.

4. Better Comfort

Traditional furnaces typically cycle between full heat and completely off.

Modern variable-speed heat pumps often operate almost continuously at lower capacities.

The result is:

• More consistent temperatures

• Better humidity control

• Reduced temperature swings

• Quieter operation

Ironically, this smoother operation also exposes one of the biggest weaknesses in many homes:

Poor air distribution.

The Comfort Problem Isn't Usually the Heat Pump

Many homeowners blame their HVAC equipment when one room is too hot while another is too cold.

In reality, the equipment often isn't the problem.

The ductwork is.

Even the most advanced inverter-driven heat pump cannot solve uneven airflow throughout a house.

Common complaints include:

• Upstairs bedrooms are too warm.

• Bonus rooms never reach the thermostat setting.

• South-facing rooms overheat.

• Finished basements stay cold.

• Home offices become uncomfortable during the afternoon.

Installing a larger heat pump usually makes these problems worse.

The real solution is controlling where conditioned air goes.

That's exactly what zoning accomplishes.

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• 1 stage COOL <> 2 stage HEAT

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SmartZone-4X 3.0

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4-Zone Controller

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Replace almost any brand existing zone control ... use with any thermostats (including WiFi).

Control heating and cooling comfort room by room.

• EASY INSTALLATION - no screwdriver or voltmeter required

• UNIVERSAL COMPATIBILITY - drop in replacement for many models (see list in Additional Info)

• BEST FEATURES - built in Fresh Air Control, expansion port up to 20 Zones

• SUPPLY AIR TEMP SENSOR - included for Smart-Staging & equipment protection

• DESIGNED & ASSEMBLED IN THE USA

• LEARN MORE

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Why Zoning Makes Heat Pumps Even Better

A zoning system divides a home's ductwork into independently controlled areas.

Each zone has its own thermostat.

Motorized dampers regulate airflow so the system sends conditioned air only where it's needed.

Instead of treating the entire home as one giant room, zoning allows every area to receive individualized comfort.

This approach offers several advantages.

More Even Temperatures

Instead of overheating one portion of the house to satisfy another, each zone receives only the heating or cooling it requires.

Longer, More Efficient Run Times

Heat pumps perform best during longer operating cycles.

Rather than frequent starts and stops, zoning helps maintain steadier operation while reducing unnecessary conditioning of unoccupied spaces.

Reduced Energy Waste

Why cool an empty guest room?

Why heat unused bedrooms during the day?

Zoning allows homeowners to condition only occupied areas.

Better Humidity Control

Because heat pumps often operate longer, they remove moisture more effectively during cooling season.

When combined with intelligent zoning, homeowners experience greater comfort even at slightly higher thermostat settings.

SmartZone Was Designed With Modern Heat Pumps in Mind

As heat pump adoption continues to rise, HVAC controls have become increasingly important.

The controller—not just the equipment—determines how intelligently the entire system operates.

The SmartZone family of zone controllers from Ecojay was designed specifically to maximize the performance of modern HVAC equipment, including today's increasingly popular heat pumps.

Rather than simply opening and closing dampers, SmartZone manages system operation using features that improve both comfort and efficiency.

Some highlights include:

• Support for conventional HVAC equipment and heat pumps

• Multi-stage heating and cooling support

• Intelligent staging based on time and temperature

• Adjustable high and low balance points

• Fresh-air ventilation integration

• ECO/Away Mode

• Optional economizer control

• Expandable zoning on larger systems

Instead of relying on a one-size-fits-all approach, SmartZone allows contractors to configure systems for each home's unique needs.

Heat Pumps Benefit From Intelligent Staging

One of the biggest differences between gas furnaces and heat pumps is how they produce heat.

Gas furnaces generally produce large amounts of heat very quickly.

Heat pumps produce lower-temperature air over longer periods.

That isn't a disadvantage—it simply requires smarter control.

An advanced zoning controller can:

• Delay auxiliary heat until truly needed

• Prevent unnecessary second-stage operation

• Coordinate airflow between multiple zones

• Maintain comfort while maximizing heat pump efficiency

These control strategies become increasingly important as homeowners invest in high-efficiency variable-capacity systems.

Fresh Air Ventilation Is Becoming More Important

Modern homes are tighter than ever.

While improved insulation reduces energy use, it also limits natural ventilation.

Many builders now incorporate:

• ERVs (Energy Recovery Ventilators)

• HRVs (Heat Recovery Ventilators)

• Dedicated fresh-air systems

These systems improve indoor air quality but require coordination with the HVAC equipment.

SmartZone includes built-in fresh-air control capabilities, allowing ventilation systems to operate without requiring additional control panels in many applications.

The Contractor Advantage

Contractors are seeing more homeowners ask specifically for heat pumps.

Many are replacing aging furnaces with dual-fuel systems or all-electric solutions.

Offering zoning alongside a heat pump installation provides several benefits:

• Better comfort

• Greater customer satisfaction

• Reduced comfort complaints

• Improved system performance

• Higher perceived value

Instead of selling only new equipment, contractors deliver an entire comfort solution.

Satisfied homeowners are also more likely to recommend contractors who solved uneven temperatures that existed for years.

Heat Pumps Are Here to Stay

The HVAC industry has experienced many technology shifts over the decades.

Electronic ignition replaced standing pilot lights.

Variable-speed blowers replaced PSC motors.

Smart thermostats became mainstream.

The rapid growth of heat pumps is another major milestone.

Whether driven by efficiency, technology improvements, utility costs, or homeowner preference, the trend is unmistakable.

Industry shipment data continues to show heat pumps gaining market share over traditional gas furnaces, and manufacturers continue investing heavily in new heat pump technologies.

As more homeowners choose heat pumps, the importance of proper airflow management becomes even greater.

The Future of Comfort Is Intelligent Control

Installing a high-efficiency heat pump is only part of the equation.

Without proper airflow management, even the best HVAC equipment cannot eliminate hot and cold spots throughout a home.

That's why zoning continues to grow alongside heat pump adoption.

A quality zoning system helps homeowners get the maximum benefit from their HVAC investment while improving comfort, reducing wasted energy, and allowing every room to receive the attention it deserves.

For contractors installing today's heat pumps, pairing them with a modern zoning controller like Ecojay SmartZone isn't simply an upgrade—it's one of the smartest ways to unlock the full potential of the system.

References

For readers who want to explore the underlying market data:

• AHRI Monthly Shipment Statistics

• AHRI Statistics Portal

• RMI Heat Pump Market Tracker

2016 USER QUESTIONS - SmartZone Advanced

QUESTION: I have two 9580 thermostats one in the office, the other in the main hangar bay (two zones).  When heating both zones or only the hangar, I need the furnace to go full blower with normal scheduling through stages 1 and 2.  When servicing only the small office area, I don't want the system to advance from stage 1.  Unfortunately, the office is so small and the modulating schedule of the furnace is still too much airflow for the office (the zone bypass when servicing the office is the main hangar modulating damper that is controlled via SPC (excess dumps into hangar)).  This damper will be wide open during call for hangar heat.  The main damper control logic is managed through a 3PDT  24 Vac relay. So, I need to block out stage 2 from only 1 zone (office).  The zone ramping schedule of the 9580 works well with the 100k modulating furnace control board, and would like to keep that capability. 

ANSWER: Configure the zone 1 thermostat connector STAT TYPE to G2 (conventional gas/electric) or H2 (heat pump) to allow the thermostat to control staging and use the hangar thermostat on zone 1. Wire only the stage 1 circuits (Y1 and W1) on the office thermostat to the zone 2 thermostat connector (Also connect R, C and G wires). Set dipswitch 4 to the LOCKOUT position. This will configure the zone controller to allow 2nd stage only when the hangar thermostat calls for 2nd stage regardless of whether the office thermostat is calling. When the office thermostat is calling and the hangar thermostat is not, SmartZone will not allow 2nd stage to operate.

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“I called last week to inquire about using this zone controller in a hangar that had a small office area and a large bay. I advised the call taker that I had Honeywell 9580. I also asked about the capability of the zone controller to handle the smaller office area’s lower CFM requirement and whether or not I could defeat the step-up from W1/Y1 to W2/Y2. I was told that the controller can be set up to defeat the stage step-ups.

After reading the manual, I found that there are no multi-stage inputs on the controller board from thermostats. So, basically, the capabilities of the Honeywell 9580 are wasted. Also, the stage defeat is for the whole system, not zone-specific as I need. It would be pointless to defeat stage increases while heating/cooling a large hangar space”

ANSWER: The SmartZone controller typically controls staging based on the total system conditions which is the most efficient way to operate a multi-zoned multi-staged hvac system. However, the zone1 thermostat connector on SmartZone can be configured to allow the thermostat to control staging (refer to the top of page 10 of the installation manual). When the zone1 thermostat is configured for staging the ability to lockout 2nd stage with only 1 zone calling is disabled. With the thermostat controlling staging your ability to limit staging will be determined by the features of your Honeywell 9580 instead of the SmartZone control.

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“I have a honeywell mastertrol2 mm2, i wanted to update my thermostats but my zone controller has separate b and o wires going to thermostats . Will updating my zone controller to a smart zone 2 help this problem?”

ANSWER: Updating your zone controller to a SmartZone 2 zone controller will allow you to use any 24VAC thermostat. SmartZone controls are designed to be universally compatible with 24VAC thermostats including WI-FI models used to control your thermostat remotely through the internet on your smart phone or tablet. You should be able to connect any 24VAC thermostat to a SmartZone control without any problems.

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“Do you have a digital thermostat that you recommend or sell to go with SmartZone?”

From ecobee.com

ANSWER: ZoningSupply does not carry thermostats, however, SmartZone controllers are compatible with any 24VAC powered 5 or 6 wire thermostat. Popular brands our customers install with SmartZone include Honeywell, ICM, Braeburn, Nest, Ecobee, Aprilaire, Lux, Lyric,  and MANY others. We suggest you avoid using low priced 'power stealing' thermostats as they may cause intermittent issues if your utility power fluctuates. Power stealing thermostats are typically low priced and can be identified by the lack of a C (common) terminal on the thermostat wall mounting plate.
If you are looking for a WiFi thermostat check out this other article:
http://zoningsupply.com/blog/best-wifi-thermostat-for-zoning

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