Heat Pumps for Pools and Spas

What Size Pool or Spa Heat Pump Do You Need?

Use our Australian Pool & Spa Heat Pump Size Calculator to estimate the heating capacity required for your swimming pool, spa or swim spa.

Unlike basic sizing tables that consider only water volume, our calculator also considers the factors that determine actual heat loss and heating performance:

Pool or spa dimensions and water volume
Water surface area
Australian city and local climate
Required swimming season
Target water temperature
Pool or spa cover type
Wind exposure and shading
Indoor or outdoor installation
Daily operating hours
Required spa heating speed

The calculator estimates the required heat pump output in kilowatts, expected heat-up performance and approximate electricity consumption. It also includes detailed heat pump sizing charts for covered pools, uncovered pools and spas in different Australian climates.

Calculate Your Heat Pump Size

Do Not Choose a Heat Pump From Pool Volume Alone

Pool heat pump sizing is primarily determined by heat loss from the water surface. Surface area, wind, air temperature, target water temperature, operating hours and cover use can be more important than the total number of litres. Pool volume mainly determines how long the initial heat-up will take.

Pool and spa heat pumps are physically stocked for fast shipping or local pick-up, with stock distributed from VIC, NSW, QLD and WA.

Shop pool heat pumps, spa heat pumps and swim spa heat pumps for efficient water heating in Australian conditions. Our range includes compact residential heat pumps, full-inverter pool heaters, high-temperature spa heat pumps, side-discharge and top-discharge units, single-phase models and larger three-phase heating systems.

We stock heat pumps and associated control equipment from brands including SensaHeat, SensaPool, Madimack, Rheem, Raypak and AstralPool. Available heating capacities extend from approximately 9kW to more than 40kW, covering small spas and plunge pools through to larger residential swimming pools and commercial applications.

How Does a Pool Heat Pump Work?

A pool or spa heat pump collects heat from the surrounding air and transfers it into the circulating water through a heat exchanger. Electricity operates the compressor, fan and control system, but most of the delivered heat is drawn from the surrounding air rather than being created directly by an electric heating element.

This makes a correctly sized heat pump substantially more energy-efficient than conventional electric resistance heating under suitable operating conditions. Actual efficiency depends on air temperature, humidity, water temperature, compressor speed and the required heating load.

Choosing the Correct Pool Heat Pump Size

The correct heat pump size is the unit that can replace the heat being lost by the pool while operating for the available number of hours each day. It must also have sufficient capacity to bring the water up to temperature within an acceptable period.

Pool heat loss is affected by:

Water surface area
Air temperature
Target pool temperature
Wind exposure
Evaporation
Night-time heat loss
Shade and available solar gain
Pool cover type and frequency of use
Length of the required swimming season
Daily filtration and heat pump operating hours

A heat pump that is too small may run continuously, take too long to heat the water or fail to maintain the selected temperature during colder weather. Selecting the next practical model above the calculated minimum can provide faster heating, improved cold-weather performance and additional reserve capacity.

Use the Australian Pool & Spa Heat Pump Size Calculator and Sizing Charts before selecting a model.

Choosing a Spa or Swim Spa Heat Pump

Spa heat pump sizing is different from pool heat pump sizing. A spa is usually covered and has a relatively small surface area, so maintaining temperature is not normally the main sizing problem. The primary consideration is how quickly the heat pump must raise the water to approximately 36°C to 38°C.

A larger spa heat pump will increase the water temperature faster. A smaller unit may still maintain the temperature once the spa is hot, but it can require considerably longer to heat the spa from cold.

For portable spas and swim spas, compatibility with the existing spa control system must also be considered. Some installations require a heat-demand controller, relay interface, universal heat pump controller or additional circulation plumbing.

Inverter Pool and Spa Heat Pumps

Most modern pool and spa heat pumps use inverter compressor technology. An inverter heat pump can vary compressor and fan speed according to heating demand instead of operating only at full output.

Potential benefits include:

Quieter operation when maintaining temperature
Reduced electrical starting current
Improved efficiency under partial load
More stable water temperature control
Reduced full-speed compressor operation

Many heat pumps in this collection also include titanium heat exchangers, Wi-Fi or app control, heating and cooling modes, automatic defrost and soft-start operation. Features vary between individual models and should be confirmed in the product description.

Understanding Heat Pump COP Ratings

COP is not a fixed efficiency rating.

A heat pump’s coefficient of performance changes with air temperature, water temperature, humidity, compressor speed and heating demand. Maximum advertised COP figures are normally measured under favourable test conditions and should not be treated as the efficiency the unit will achieve while heating a pool in winter or a spa to 38°C.

A COP of 5 means that the heat pump supplies approximately 5kW of heat for every 1kW of electricity consumed under the stated test conditions. As the air becomes colder or the required water temperature increases, available heating output and COP generally decrease.

When comparing heat pumps, consider:

Heating output at clearly stated air and water temperatures
Maximum electrical input
Operating temperature range
Noise output
Single-phase or three-phase requirements
Required water flow rate
Warranty support and spare-parts availability
Suitability for the required final water temperature

Pool and Spa Heat Pump Installation

A pool or spa heat pump must have adequate airflow, drainage, plumbing flow and electrical supply. It should not be enclosed or installed where discharged cold air will recirculate through the unit.

We also stock:

Heat pump three-way bypass valve kits
Heat-demand controllers
Universal pool and spa heat pump controllers
J-box and MJ-box control interfaces
Associated plumbing and control equipment

A bypass valve arrangement allows water flow through the heat pump to be adjusted and permits the unit to be isolated for service. Electrical installation must be completed by a suitably licensed electrician in accordance with the manufacturer’s requirements and applicable Australian standards.

Frequently Asked Pool and Spa Heat Pump Questions

What size heat pump do I need for my pool?
The required size depends on surface area, location, swimming season, target temperature, wind, shade, pool-cover use and daily operating hours. Water volume alone is not sufficient. Use our Pool Heat Pump Size Calculator for an estimated output requirement.

Is a larger pool heat pump better?
A larger heat pump generally heats faster and has more capacity during colder weather. It may also reach the target temperature without operating continuously. The unit still needs to be compatible with the available electrical supply, plumbing flow and installation space.

Can a pool heat pump heat a spa to 40°C?
Some pool and spa heat pumps are designed to operate at spa temperatures, but not every model has the same maximum water-temperature setting or cold-weather capacity. Check the individual model specifications before ordering.

How much electricity does a pool heat pump use?
Electricity consumption depends on the unit’s electrical input, operating time, air temperature, water temperature and heat loss from the pool. An uncovered or wind-exposed pool can require substantially more heating than a covered and sheltered pool.

Should I cover my pool when using a heat pump?
Yes. A suitable pool cover reduces evaporation and overnight heat loss. Cover use can materially reduce the heating capacity and electricity required to maintain the selected water temperature.

Can I use a heat pump all year?
Year-round heating is possible when the heat pump is sized for the coldest operating conditions expected at the site. A unit sized only for summer operation may not maintain the same temperature during winter.