A heat pump can be one of the most efficient ways to keep a Christchurch home warm through winter and comfortable during summer—but only when the system is correctly selected, sized and installed.
Choosing a heat pump based solely on the room’s floor area or the lowest advertised price can result in poor performance, higher power consumption and uneven temperatures. Christchurch homes also face conditions that are easy to underestimate, including cold overnight temperatures, frosts, older insulation and large open-plan living areas.
At Plains Electrical, we install heat pumps throughout Christchurch and Selwyn. This guide explains what homeowners should consider before choosing a system, including heat-pump sizing, placement, efficiency, running costs and the differences between high-wall and ducted systems.
Why are heat pumps so popular in Christchurch?
Heat pumps do not create heat in the same way as a conventional electric resistance heater. Instead, they use refrigerant and a compressor to transfer heat from the outdoor air into your home.
Even during cold weather, there is heat energy available in the outside air. A suitably selected heat pump extracts that energy and transfers it indoors. In summer, the process can be reversed to remove heat from your home and provide cooling.
The main benefits include:
- Energy-efficient home heating
- Heating and cooling from the same appliance
- Fast temperature control
- Programmable timers and Wi-Fi control on compatible models
- No combustion or fuel storage inside the home
- Options for heating a single room or an entire house
- Effective air circulation and filtration
A heat pump is not automatically efficient simply because it is new. Its performance depends heavily on correct sizing, equipment selection, placement and installation quality.
What size heat pump does a Christchurch home need?
There is no single heat-pump size that suits every room of the same floor area.
Two living rooms may both measure 50 square metres, but one could be a modern, well-insulated room with double glazing, while the other has a high ceiling, large windows and limited insulation. Their heating requirements may be significantly different.
A proper heat-loss assessment should consider:
- The room’s length, width and ceiling height
- Wall, ceiling and underfloor insulation
- Window size and glazing type
- The number and size of exterior walls
- Sun exposure and room orientation
- Draughts and air leakage
- Open stairwells and adjoining rooms
- The age and construction of the house
- Typical Christchurch winter temperatures
- How quickly the homeowner expects the room to warm up
Correct sizing is particularly important in Canterbury because a heat pump’s available heating output can reduce as the outside temperature falls. EECA’s heat-pump installation guidance recommends selecting equipment that can provide the required heating capacity at the relevant outdoor design temperature—not simply relying on its headline or nominal capacity.
What happens if a heat pump is too small?
An undersized heat pump may:
- Run almost continuously
- Struggle during frosts and cold southerly conditions
- Take too long to warm the room
- Use more electricity than expected
- Produce excessive airflow without achieving an even temperature
- Experience increased wear from operating at maximum output
Can a heat pump be too large?
Yes. Oversizing is not necessarily better.
A substantially oversized system may reach the thermostat setting too quickly and cycle on and off more frequently. It can also create noticeable drafts, uneven temperatures and unnecessary upfront cost.
Modern inverter heat pumps can reduce their output as demand changes, but the system still needs to be selected within a sensible operating range.
The best heat pump is one that can comfortably meet the home’s heating demand on a cold Christchurch day while operating efficiently during milder conditions.
High-wall or ducted heat pump: which is better?
The right answer depends on how much of the home you want to heat, the building layout and your available budget.
High-wall heat pumps
A high-wall heat pump consists of an indoor unit mounted near ceiling level and an outdoor compressor unit.
High-wall systems are well suited to:
- Living rooms
- Open-plan kitchen and dining areas
- Bedrooms
- Home offices
- Smaller homes
- Heating a frequently occupied part of the house
Their advantages include a lower installation cost than a full ducted system, fast room heating and individual control.
However, one high-wall heat pump should not automatically be expected to evenly heat every room in a house. Heat does not reliably travel through closed doors, around corners or down long hallways. If several separated areas need consistent heating, multiple indoor units or a ducted system may be more appropriate.
Ducted heat pumps
A ducted heat pump uses a central indoor unit, usually installed in the roof space or beneath the floor. Insulated ducting distributes conditioned air through ceiling or floor grilles.
Ducted systems are well suited to homeowners wanting:
- Whole-home heating and cooling
- A discreet appearance
- More consistent temperatures between rooms
- Centralised control
- Optional zoning for different parts of the house
A well-designed ducted system must account for both supply air and return air. Duct sizing, grille selection, airflow balancing, insulation and equipment access all affect performance.
Poor ductwork design can make an otherwise good heat pump noisy or inefficient. The design of the air-distribution system is just as important as the brand of the heat pump itself.
Where should the indoor unit be installed?
Indoor-unit position has a major effect on comfort.
A high-wall unit should generally be placed where it can distribute air across the occupied space without being obstructed by tall furniture, curtains or architectural features.
Important considerations include:
- Airflow direction
- The shape of the room
- Ceiling height
- Seating and sleeping positions
- Access for filter cleaning and servicing
- Refrigerant pipe and condensate-drain routes
- The appearance of external pipe capping
- Potential noise transfer into bedrooms
Installing a powerful unit directly above a sofa or bed can create uncomfortable airflow. Mounting it in a corner may also restrict how well it circulates air throughout a large room.
The best position is not always the easiest position. It should balance comfort, performance, appearance and practical installation requirements.
Where should the outdoor unit be located?
The outdoor unit needs unrestricted airflow and enough space to operate, drain and be serviced.
It should not be enclosed in a tight cupboard or surrounded by vegetation. It must also be positioned carefully in relation to bedroom windows, neighbouring properties and outdoor living areas.
A suitable location should consider:
- Manufacturer-required clearances
- Airflow around the unit
- Compressor and fan noise
- Access for future servicing
- Condensate and defrost-water drainage
- Exposure to debris and vegetation
- Mounting on a suitable base, wall bracket or feet
- The appearance and length of the pipe route
During cold weather, an outdoor unit may enter a normal defrost cycle to remove ice from its coil. Water produced during this process needs somewhere appropriate to drain. Poor drainage can create persistent wet areas or ice around the unit during freezing conditions.
What temperature should a heat pump be set to?
For most homes, approximately 18°C to 21°C is a comfortable and practical heating range.
Setting the remote to 28°C does not necessarily make the room warm up faster. It generally tells the unit to keep operating until a much higher temperature is reached.
EECA recommends a thermostat setting of around 20°C for efficient home heating. It also advises selecting heating mode rather than relying on automatic mode, which can cause some systems to switch unnecessarily between heating and cooling.
For effective winter operation:
- Select HEAT mode, usually shown by a sun symbol.
- Set the temperature to approximately 20°C.
- Use AUTO fan speed unless there is a reason to change it.
- Direct the airflow downward or across the occupied area.
- Close doors to rooms that are not being heated.
- Use the timer to warm the room before it is needed.
- Avoid repeatedly turning the system on and off over short periods.
The most efficient operating strategy depends on the home’s insulation, occupancy and electricity plan. In many homes, maintaining a sensible temperature during occupied periods is more comfortable than allowing the room to become extremely cold before reheating it.
How much does a heat pump cost to run?
There is no universal hourly running cost. Actual electricity use depends on:
- The heat pump’s input power at the time
- Outdoor temperature
- Thermostat setting
- Insulation and draughts
- Room size
- Occupancy
- Filter and coil condition
- Local electricity rates
- How long the system operates
- Whether the unit is correctly sized
The rated heating capacity shown on a heat pump is not the same as its electrical input. For example, a unit may provide several kilowatts of heating while consuming considerably less electrical power because it transfers heat rather than producing all of it through electrical resistance.
When comparing models, look beyond the purchase price. Consider:
- Heating output at low outdoor temperatures
- Energy-star performance
- Seasonal efficiency
- Minimum and maximum heating capacity
- Noise levels
- Warranty support
- Replacement-part availability
- Suitability for the local climate
A slightly cheaper unit that struggles in cold conditions may deliver worse long-term value than a correctly selected system with strong low-temperature performance.
How often should heat-pump filters be cleaned?
During periods of frequent use, the filters should generally be checked and cleaned approximately once a month, or according to the manufacturer’s instructions.
Dirty filters restrict airflow, make the heat pump work harder and can reduce heating performance.
A basic homeowner clean usually involves:
- Turning the unit off.
- Opening the indoor-unit cover.
- Carefully removing the mesh filters.
- Vacuuming them or washing them in warm water.
- Allowing them to dry completely.
- Reinstalling them correctly.
Filter cleaning is not the same as professional servicing. An experienced technician can also inspect the indoor coil, outdoor coil, condensate system, electrical connections, airflow, refrigerant performance and overall condition of the equipment.
Can a heat pump help with condensation?
A heat pump can make a room warmer, and warm surfaces are generally less likely to reach the temperature at which condensation forms. Cooling mode can also remove some moisture from indoor air during summer.
However, a heat pump is not a complete ventilation system.
It recirculates indoor air rather than continually replacing stale, moisture-laden air with fresh outside air. Moisture produced by showers, cooking, drying clothes and occupants still needs to be managed through effective extraction and ventilation.
Homes with ongoing condensation or dampness may require a combination of:
- Adequate heating
- Bathroom and kitchen extraction
- A suitable home-ventilation system
- Improved insulation
- Draught management
- Identification of external water or ground-moisture problems
Heating and ventilation perform different jobs, but they work best together.
Are heat pumps suitable for rental properties?
A qualifying heat pump can be used to meet the Healthy Homes heating standard when it is correctly located, fixed in place and capable of providing the required heating capacity.
The standard generally requires a qualifying fixed heater in the main living room that can heat the room to at least 18°C, subject to the applicable rules and exemptions.
A casual room-size estimate should not be used as a substitute for the required Healthy Homes heating assessment. Landlords should ensure that the selected heater meets the calculated requirement and that supporting documentation is retained.
Common heat-pump installation mistakes
Many heat-pump problems start before the unit is switched on.
Common mistakes include:
- Selecting equipment using floor area alone
- Ignoring Christchurch’s low winter temperatures
- Expecting one unit to heat multiple closed bedrooms
- Positioning the indoor unit where airflow is obstructed
- Placing the outdoor unit too close to a bedroom
- Failing to plan condensate and defrost drainage
- Choosing appearance over effective air distribution
- Using poorly insulated or undersized ductwork
- Providing inadequate return-air paths in ducted systems
- Focusing only on the cheapest upfront price
- Failing to explain the controls to the homeowner
A professional installation should finish with commissioning and a clear explanation of how to use and maintain the system.
Questions to ask before accepting a heat-pump quote
Before proceeding, ask:
- How was the required heating capacity calculated?
- Has low-temperature heating performance been considered?
- Why has this particular model been recommended?
- Will the proposed location heat the intended area evenly?
- Where will the condensate and defrost water drain?
- How will the pipework and exterior capping look?
- Is all electrical work included?
- Does the quote include installation, commissioning and removal of packaging?
- What warranty applies to the equipment and installation?
- Is Wi-Fi control included or available as an option?
- Who should I contact if the system needs servicing?
A good installer should be able to clearly explain the recommendation rather than simply supplying a model number and price.
Heat-pump installation in Christchurch and Selwyn
Every home is different. The most suitable solution might be a compact bedroom heat pump, a powerful high-wall unit for an open-plan living area, multiple individually controlled systems, or a fully ducted whole-home installation.
Plains Electrical provides heat-pump installation throughout Christchurch and Selwyn, including Prebbleton, Lincoln, Rolleston and surrounding areas.
We can assess your home, discuss how you use each space and recommend a system based on performance, comfort, appearance and budget.
Ready for a warmer home?
If your current heater cannot keep up, your existing heat pump needs replacing, or you are considering a new whole-home solution, talk to Plains Electrical.
Contact us today to arrange a heat-pump assessment and installation quote in Christchurch or Selwyn.
Frequently asked questions
What is the best heat pump for a Christchurch home?
The best heat pump is one that is correctly sized for the room, performs well at low outdoor temperatures and has suitable local warranty and parts support. The best brand or model will vary depending on the house and intended use.
What size heat pump do I need for a large living room?
Floor area alone is not enough to accurately size a heat pump. Ceiling height, insulation, glazing, exterior walls, orientation and Christchurch winter conditions should all be considered.
Can one heat pump heat an entire house?
It may heat a small or open-plan home, but warm air will not reliably reach separated rooms through closed doors and hallways. Multiple systems or a ducted heat pump may provide better whole-home comfort.
Do heat pumps still work when it is below zero?
Yes, modern heat pumps are designed to operate in cold conditions. However, their heating output and efficiency can change as outdoor temperatures fall, so low-temperature performance must be considered during selection.
Is it cheaper to leave a heat pump running all day?
Not always. It depends on insulation, outdoor temperature, thermostat setting, occupancy and the system itself. Timers and sensible temperature settings can prevent unnecessary operation while keeping the home comfortable.
Does a heat pump bring fresh air inside?
Most residential high-wall and ducted heat pumps recirculate indoor air. They do not normally provide continuous fresh-air ventilation unless a separate ventilation component has been specifically designed into the system.
How long does heat-pump installation take?
A straightforward high-wall installation can often be completed within a day. Complex pipe routes, switchboard work, multiple units and ducted systems may require additional time.
How often should a heat pump be serviced?
Filters should be cleaned regularly by the homeowner. Professional servicing frequency depends on usage, environment and manufacturer recommendations, but the unit should be inspected if performance drops, unusual noises develop or water begins leaking
call Dominic Drury – 0277524700