How to Use an Air Source Heat Pump Correctly: 8 Essential Operating Habits Every Homeowner Should Know

A Practical Guide to Safe Operation, Energy Efficiency, Winter Freeze Protection, and Long-Term Heat Pump Maintenance

Air source heat pumps are becoming increasingly popular for residential heating, underfloor heating, and domestic hot water applications. Their high energy efficiency, environmental benefits, and ability to provide comfortable indoor temperatures make them an attractive alternative to conventional heating systems.

However, installing a high-quality heat pump is only the beginning.

Proper operation and regular maintenance are equally important to achieving reliable heating performance, lower electricity consumption, and a longer equipment service life.

Many homeowners are unfamiliar with heat pump technology, particularly when switching from gas boilers, electric heaters, or other traditional heating systems.

As a result, seemingly harmless operating habits—such as frequently switching off the power, setting excessively high water temperatures, or ignoring defrost drainage—can lead to unnecessary energy consumption, heating problems, or even equipment damage.

In this technical guide, we explain eight essential operating habits that every heat pump owner should understand.

Whether you are a homeowner, HVAC installer, heating contractor, or heat pump distributor, these recommendations can help improve system reliability and customer satisfaction.

1. Never Switch Off the Main Power Supply Without Considering Freeze Protection

Why does an air source heat pump need electricity even when it is not heating?

One of the most common mistakes homeowners make is completely disconnecting their heat pump from the electrical supply whenever heating is not required.

For example, a homeowner may switch off the heat pump during the daytime while away from home, believing this will reduce electricity consumption.

Although this approach may appear economical, it can create serious problems during freezing weather.

Unlike a conventional electric heater, an air-to-water heat pump transfers heat through a water-based hydraulic circuit.

This circuit may include:

• The heat pump's internal heat exchanger

• Water supply and return pipes

• Circulation pumps

• Buffer tanks

• Underfloor heating manifolds

• Radiators or fan coil units

When outdoor temperatures fall below freezing, water inside exposed pipes or heat exchangers may freeze if adequate protection is unavailable.

As water freezes, it expands. This expansion can damage pipes, fittings, valves, and heat exchangers.

How does built-in freeze protection work?

Many modern air-to-water heat pumps include automatic freeze protection functions.

Depending on the equipment design, the controller may activate the circulation pump, start the compressor, or energize an auxiliary heater when monitored temperatures fall below predefined thresholds.

These functions help maintain safe water temperatures during cold weather.

However, an important limitation must be understood:

Electronic freeze protection generally requires an available electrical supply, a functioning controller, and correctly configured hydraulic components.

If the main power supply is disconnected, electrically powered freeze protection may become unavailable.

Recommended operating practice

During winter, homeowners should normally leave the heat pump connected to the electrical supply and use the manufacturer's standby, holiday, or frost-protection mode when space heating is not required.

Avoid disconnecting the main circuit breaker merely to reduce electricity consumption.

The correct operating mode depends on the manufacturer's instructions and the installation design.

What should homeowners do during an extended power outage?

A prolonged winter power outage requires special attention.

If freezing temperatures are expected and the heating system cannot operate, homeowners should contact their installer to determine the appropriate protection measures.

Possible solutions include:

1. Using an approved antifreeze solution where compatible with the equipment and system.

2. Installing properly designed mechanical freeze-protection valves.

3. Providing backup electrical power for essential protection equipment.

4. Draining vulnerable water circuits according to the manufacturer's winterization procedure.

Draining a system is not always as simple as opening a valve.

Heat exchangers, low points, pipe bends, and other components may retain water even after the main circuit has been drained.

Therefore, complete winterization should be carried out by qualified personnel.

Engineering takeaway: The safest winter operating strategy is not simply to turn the heat pump off. It is to maintain reliable freeze protection under both normal and emergency conditions.

2. Learn the Basic Controller Functions Before Operating the Heat Pump

Why are incorrect controller settings a common problem?

Modern heat pumps use electronic controllers with multiple operating modes and configuration menus.

Depending on the model, these may include:

• Heating and cooling modes

• Domestic hot water settings

• Water temperature adjustment

• Room temperature control

• Weekly scheduling

• Weather compensation

• Holiday or standby mode

• Auxiliary heater settings

• Error-code display

• Installer and service parameters

For homeowners unfamiliar with these functions, changing the wrong setting may prevent the heat pump from operating as expected.

For example, accidentally activating a weekly timer could stop the system from heating during periods when indoor heating is required.

Similarly, changing advanced hydraulic or compressor parameters without understanding their purpose could affect system performance.

Which settings should homeowners be allowed to adjust?

During installation and commissioning, the HVAC contractor should explain the functions that homeowners can safely control.

These normally include:

Heating mode: Selects the appropriate operating mode for the season.

Room temperature setting: Adjusts the desired indoor comfort level where room-temperature control is supported.

Heating water temperature: Determines the target water temperature supplied to the heating system, where manual adjustment is permitted.

Scheduling: Allows heating operation to follow an appropriate daily or weekly program.

Holiday mode: Reduces heating demand during extended absences while maintaining required system protection.

Which settings should not be changed casually?

Advanced settings should generally remain under installer or service-technician control.

Examples include:

• Compressor operating limits

• Refrigerant protection parameters

• Water-flow protection thresholds

• Defrost control settings

• Electrical heater safety parameters

• Pump configuration

• Sensor calibration

• System protection logic

Changing these settings without proper technical knowledge can cause unstable operation or interfere with safety functions.

Recommended installer practice

At system handover, installers should provide a simple operating guide explaining the most frequently used buttons and functions.

Homeowners should also receive instructions on restoring normal operation after accidentally changing a user-accessible setting.

Engineering takeaway: A well-configured heat pump should be easy for homeowners to operate without requiring access to advanced engineering parameters.

3. Set a Reasonable Indoor Temperature Instead of Overheating the House

Does setting a higher room temperature make the house heat faster?

Many homeowners assume that setting the thermostat to 25°C will heat their house faster than setting it to 21°C.

In most conventional thermostatically controlled systems, this assumption is incorrect.

The thermostat primarily determines the desired indoor temperature rather than directly controlling the maximum heating capacity.

Setting an unnecessarily high temperature can extend heating operation and increase energy consumption.

For example, consider two operating scenarios:

Scenario A:

The homeowner maintains an indoor temperature of approximately 20–21°C.

Scenario B:

The homeowner continuously maintains an indoor temperature of 25°C.

Under otherwise similar conditions, Scenario B generally requires more heating energy because the temperature difference between the indoor and outdoor environments is greater.

The additional energy consumption depends on building insulation, outdoor temperature, ventilation, system controls, and heating equipment performance.

There is no universal percentage increase applicable to every building.

What indoor temperature is recommended?

For many residential applications, a heating setpoint of approximately 20–22°C provides a reasonable starting point.

However, the appropriate temperature depends on:

• Occupant preferences

• Age and health considerations

• Local climate

• Building insulation

• Humidity

• Air movement

• Heating system design

The objective is to maintain comfortable indoor conditions without unnecessary overheating.

Should homeowners frequently change the thermostat?

Frequent and large temperature adjustments are generally not ideal for underfloor heating systems.

Hydronic underfloor heating has considerable thermal inertia, especially when pipes are embedded in a thick concrete screed.

After changing the temperature setting, the system may require several hours to respond.

Repeatedly increasing and decreasing the thermostat setting can lead to unstable comfort and unnecessary control cycling.

For well-insulated homes with underfloor heating, a relatively stable indoor temperature is often preferable.

However, the most efficient setback strategy depends on the building's thermal mass, heat pump capacity, electricity tariffs, and control system.

Engineering takeaway: Comfortable heating does not require excessively high room temperatures. Stable and appropriate temperature control is usually more effective.

4. Use the Lowest Practical Heating Water Temperature

Why is water temperature so important for heat pump efficiency?

One of the fundamental differences between an air source heat pump and a traditional boiler is how heating efficiency changes with water temperature.

A heat pump generally operates more efficiently when the temperature difference between the outdoor heat source and the heating water is smaller.

As the required heating water temperature increases, the compressor must usually operate across a greater temperature lift.

This typically reduces the coefficient of performance (COP).

For example, a heat pump delivering water at 35°C will often achieve a higher COP than the same unit delivering water at 50°C under comparable outdoor conditions.

Actual performance must be verified using the manufacturer's technical data.

Typical heating water temperature ranges

These values are general reference ranges, not universal design requirements.

The actual temperature should be determined by the building heat-loss calculation, emitter capacity, outdoor design temperature, and equipment specifications.

Example: Adjusting underfloor heating temperature

Suppose a homeowner operates an underfloor heating system with a supply water temperature of 35°C.

During normal winter weather, the house maintains a comfortable indoor temperature of 21°C.

If the outdoor temperature suddenly drops and the indoor temperature can no longer reach the desired setpoint, the homeowner may need to adjust the heating curve or water temperature.

However, increasing the water temperature should not be the first response to every heating problem.

The installer should also consider:

• Insufficient system flow

• Air trapped inside heating circuits

• Blocked filters

• Poor hydraulic balancing

• Inadequate heating capacity

• Excessive building heat loss

Why weather compensation is useful

Weather compensation automatically adjusts the heating water temperature according to outdoor conditions.

When outdoor temperatures are relatively mild, the controller can reduce the heating water temperature.

As outdoor temperatures decrease, the controller increases the target water temperature according to a predefined heating curve.

This helps maintain indoor comfort while reducing unnecessary high-temperature operation.

Engineering takeaway: The objective is not to produce the hottest possible water. It is to supply the lowest water temperature that can reliably meet the building's heating demand.

5. When a Heat Pump Displays an Error Code, Contact Technical Support Before Resetting It Repeatedly

Why should homeowners pay attention to fault codes?

Air source heat pumps include multiple protection devices and monitoring functions.

Depending on the model, these may monitor:

• Water flow

• Water temperature

• Refrigerant pressure

• Compressor operating conditions

• Electrical supply

• Sensor performance

• Communication between electronic components

When abnormal operating conditions are detected, the controller may display a fault code or stop the equipment to prevent further damage.

An error code is not simply an inconvenience.

It may indicate that the system has detected a condition requiring inspection.

What should homeowners do when a fault occurs?

Step 1: Record the error code.

Take a clear photograph of the controller display.

Step 2: Record the operating conditions.

Useful information includes outdoor temperature, heating mode, water temperature, and when the fault occurred.

Step 3: Check the user manual.

Some minor alarms may have straightforward explanations and manufacturer-approved recovery procedures.

Step 4: Contact the installer or authorized service provider.

Provide the error code, equipment model, serial number, and operating information.

Step 5: Follow the recommended troubleshooting procedure.

Only perform checks or resets that are explicitly permitted for the homeowner.

Why is repeated resetting discouraged?

Repeatedly restarting a heat pump without identifying the cause may expose the equipment to recurring abnormal operating conditions.

For example, a low-water-flow alarm may indicate:

• A blocked strainer

• A closed valve

• Air inside the system

• A malfunctioning circulation pump

• Insufficient system pressure

Simply resetting the controller will not correct these underlying problems.

What should installers explain during handover?

Installers should provide the customer with the service contact details, warranty information, equipment identification, and basic fault-reporting instructions.

Engineering takeaway: Fault codes are valuable diagnostic information. Record them, investigate the cause, and avoid repeated resets without proper guidance.

6. Keep the Defrost Drainage System Clear During Winter

Why does an air source heat pump produce water during heating?

During heating operation, the outdoor heat exchanger absorbs energy from the surrounding air.

Its surface temperature may fall below the outdoor air's dew point and, under suitable conditions, below freezing.

Moisture in the air can then condense or freeze on the heat exchanger.

As frost accumulates, airflow and heat transfer become restricted.

To restore performance, the heat pump periodically performs a defrost cycle.

During defrosting, the accumulated frost melts and produces water that must be discharged safely.

What happens when defrost water cannot drain properly?

If drainage is obstructed, water may accumulate beneath the outdoor unit.

During freezing weather, this water can turn into ice.

Repeated freezing may create increasingly thick ice deposits.

Potential consequences include:

• Restricted drainage

• Ice accumulation around the unit

• Reduced airflow

• Fan obstruction

• Damage to lower heat exchanger components

• Unsafe slippery surfaces around the installation

In severe cases, ice buildup may interfere with normal operation.

How can homeowners prevent drainage problems?

Homeowners should periodically inspect the area beneath and around the outdoor unit.

Ensure that defrost water can flow away from the equipment without collecting around vulnerable components.

In cold climates, the installation may require a properly designed heated drain pan, trace heating, frost-resistant drainage arrangement, or other manufacturer-approved solution.

Important safety considerations

Never attempt to remove ice from the heat exchanger using sharp metal tools.

Do not pour boiling water onto frozen electrical or mechanical components.

Do not modify the drainage arrangement without consulting the installer.

If significant ice accumulation develops, contact a qualified technician.

Engineering takeaway: Defrosting is a normal part of winter heat pump operation. Proper drainage is essential to reliable cold-weather performance.

7. Keep the Outdoor Unit Free From Obstructions

Why does an air source heat pump need sufficient airflow?

An air source heat pump extracts thermal energy from outdoor air.

During heating operation, the outdoor fan moves air through the heat exchanger, allowing the refrigerant circuit to absorb heat.

If airflow is restricted, the amount of heat available to the system can decrease.

This may reduce heating capacity, lower efficiency, increase defrost frequency, or trigger protective controls.

Common airflow obstructions

Homeowners should avoid placing the following objects near the outdoor unit:

• Storage boxes

• Garden equipment

• Building materials

• Leaves and branches

• Plastic sheets

• Furniture

• Snow piles

• Decorative covers that restrict airflow

How much clearance does a heat pump require?

Clearance requirements vary by manufacturer, model, airflow direction, and installation environment.

Some equipment requires significant unobstructed space in front of the discharge fan, while rear and side clearances may be different.

Always follow the installation manual for the specific model rather than applying a universal clearance distance.

For example, a unit installed in a narrow courtyard may experience cold-air recirculation if discharged air is drawn back into the intake.

This reduces the effective air temperature entering the heat exchanger and can negatively affect heating performance.

Why is cold-air recirculation a problem?

During heating, the air discharged from the outdoor unit is colder than the surrounding ambient air.

If the installation layout allows this cold air to return directly to the intake, the heat pump may operate under less favorable conditions.

The result can be reduced heating capacity and efficiency.

Cleaning the outdoor heat exchanger

Leaves, dust, pollen, and other airborne contaminants can accumulate on the outdoor coil.

Homeowners may remove loose debris from accessible surrounding areas while the unit is safely isolated according to the manufacturer's instructions.

Cleaning the heat exchanger itself should follow approved maintenance procedures.

Avoid high-pressure water jets, aggressive chemicals, or mechanical methods that could damage the coil fins or electrical components.

Engineering takeaway: A heat pump needs unrestricted airflow to operate efficiently. Outdoor unit location and regular inspection are essential.

8. Establish a Preventive Maintenance Schedule

Why is regular maintenance important?

Even a properly installed heat pump can gradually lose performance if maintenance is neglected.

Over time, debris, mineral deposits, corrosion products, and other contaminants may affect the hydraulic circuit and heat exchanger surfaces.

Filters and strainers may become obstructed.

Circulation pumps, sensors, valves, and other components may also require inspection.

Preventive maintenance helps identify these issues before they develop into major failures.

Recommended maintenance checklist

A professional service inspection is commonly performed annually, although actual maintenance intervals should follow the manufacturer's instructions, local regulations, operating environment, and warranty conditions.

Why is water quality important?

Hydronic heating systems depend on proper water circulation and heat transfer.

Poor water quality may contribute to:

• Scale formation

• Corrosion

• Magnetite and sludge accumulation

• Blocked strainers

• Reduced heat exchanger performance

• Circulation problems

Water treatment requirements vary according to pipe materials, system design, water hardness, and equipment specifications.

Suitable filtration, magnetic dirt separation, corrosion protection, and water treatment may be necessary.

Homeowners should not add chemicals to the heating circuit without confirming compatibility with the heat pump and other system components.

Why is maintenance especially important before winter?

A pre-winter inspection can identify problems before the equipment enters its highest-demand operating period.

For homeowners in cold climates, particular attention should be paid to freeze protection, system pressure, circulation, defrost drainage, and outdoor airflow.

Engineering takeaway: Preventive maintenance is usually more practical than waiting for equipment failure during the coldest period of the year.

9. The Installer's Responsibility: Teach Customers How to Operate Their Heat Pumps

Although homeowners are responsible for daily operation, installers play a critical role in establishing correct operating habits.

A technically excellent installation can still result in customer dissatisfaction if the homeowner does not understand how to use the equipment.

Therefore, customer education should be considered part of the commissioning and handover process.

What should installers explain before leaving the site?

Every homeowner should understand:

1. How to switch between heating, cooling, and domestic hot water modes, where applicable.

2. How to adjust the room temperature or heating water temperature.

3. How to use standby and holiday modes safely.

4. Why the main power supply should normally remain available during freezing weather.

5. How to identify and report fault codes.

6. Why defrosting and water drainage are normal winter operating processes.

7. How to keep the outdoor unit unobstructed.

8. When to contact professional service personnel.

Installers should also explain which functions homeowners must not modify.

Why a written handover guide matters

A simple operating guide can prevent many unnecessary service calls.

For distributors and HVAC contractors, standardized customer training can also improve after-sales efficiency.

Customers who understand normal heat pump operation are less likely to mistake defrost cycles, variable fan speeds, or gradual underfloor heating response for equipment failures.

This can reduce misunderstandings and improve long-term customer confidence.

10. Quick Reference: Common Heat Pump Operating Mistakes

Frequently Asked Questions About Air Source Heat Pump Operation

Q1. Should I turn off my air source heat pump at night?

Not necessarily.

For many homes using underfloor heating, maintaining a relatively stable temperature is practical because the heating system responds slowly to temperature changes.

A small nighttime setback may be appropriate in some buildings, but the optimum strategy depends on insulation, thermal mass, electricity tariffs, and control configuration.

During freezing weather, avoid disconnecting power if the system depends on electrically powered freeze protection.

Q2. What is the most efficient temperature for an air source heat pump?

There is no single temperature that is optimal for every installation.

In general, heat pumps operate more efficiently at lower heating water temperatures, provided those temperatures are sufficient to meet the building's heating demand.

Many underfloor heating systems operate within approximately 30–40°C supply water temperature, depending on design conditions.

Q3. Is it normal for an air source heat pump to stop heating temporarily during winter?

Yes.

Many air source heat pumps periodically enter a defrost cycle to remove frost from the outdoor heat exchanger.

During defrosting, space heating output may temporarily decrease or pause.

However, unusually frequent or prolonged defrosting may require technical investigation.

Q4. Can an air source heat pump freeze during a power outage?

Yes.

Water-containing components may be vulnerable to freezing if power is unavailable and suitable passive protection has not been installed.

The level of risk depends on outdoor temperature, outage duration, system design, and freeze-protection measures.

Q5. How often should an air source heat pump be serviced?

An annual professional inspection is a common starting point.

However, the actual maintenance schedule should follow the manufacturer's requirements, local regulations, and operating conditions.

Homeowners should also regularly check for airflow obstructions, unusual alarms, and drainage problems.

Q6. Why is my heat pump running but the house is not getting warm?

Possible causes include insufficient heating capacity, low water temperature, inadequate water flow, trapped air, blocked filters, poor hydraulic balancing, or excessive building heat loss.

A qualified technician should evaluate the complete heating system rather than assuming the heat pump itself is defective.

Q7. Can I clean the outdoor heat exchanger myself?

Homeowners can usually remove loose debris from the surrounding area if this can be done safely.

Cleaning the heat exchanger directly should follow the manufacturer's instructions.

If the coil is heavily contaminated, professional cleaning is recommended.

Q8. Does increasing the heat pump water temperature always improve comfort?

No.

Higher water temperature may increase heat output from radiators or underfloor heating, but it can also reduce heat pump efficiency.

If the underlying problem is inadequate water flow, poor balancing, or insufficient heat-emitting area, increasing the temperature may not solve the root cause.

Conclusion: Good Operating Habits Are Essential to Heat Pump Performance

An air source heat pump is more than a heating appliance. It is an integrated system involving refrigeration technology, water circulation, electronic controls, heat distribution, and building thermal performance.

To achieve reliable and efficient operation, homeowners need to understand a few fundamental principles:

Maintain freeze protection. Use appropriate temperature settings. Avoid unnecessary controller adjustments. Keep airflow and drainage clear. Respond correctly to faults. Perform regular maintenance.

These habits can help reduce avoidable failures, improve indoor comfort, and support long-term equipment performance.

For HVAC installers and heat pump distributors, customer education should never be treated as an optional service.

A successful installation is not complete until the homeowner understands how to operate the system safely and efficiently.

Professional Discussion Welcome

We welcome HVAC engineers, heat pump installers, system designers, and heating specialists worldwide to review this article and share their practical experience.

If you identify anything that should be corrected, expanded, or improved, your professional feedback is highly appreciated.

Technical knowledge improves through engineering practice, field experience, and open discussion.

For more technical articles, heat pump engineering insights, and professional heating solutions, visit:

www.ecoheat-pump.com

Better Engineering. Higher Efficiency. Greater Comfort.

About Us

We specialize in air source heat pump technology, including air-to-water heating and cooling systems, residential heating solutions, commercial heat pumps, and OEM/ODM heat pump manufacturing.

Through continuous product development, engineering collaboration, and practical application experience, we aim to help international distributors, installers, and project developers deliver reliable, energy-efficient heating solutions.