Choosing a Heat Pump for a Spa
Why a spa is not just a small pool, and what that changes about the heat pump you buy.
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A heat pump for spa use in Australia is almost always a 9kW to 12kW unit, and the choice comes down to one question: does your spa run a SpaNET SV Series control or not. If it does, an integrated heat pump like the Spanet 9.0kW SV Series plugs straight into the spa control and takes over from the element. If it does not, you fit a small standalone pool heat pump instead and run it off its own keypad. Both work. They are just wired and controlled in completely different ways.
That is the whole decision in a paragraph. Here is the detail behind it.
A spa is a different heating job to a pool
A spa holds a tenth of the water a pool does but wants it 10 degrees hotter, and wants it hot every day of the year. That combination is what makes spa heating expensive. A 2,500L spa at 38 degrees is a harder ask on a July night in Adelaide than a 40,000L pool sitting at 28 degrees in February.
Three things fall out of that:
- Small kW, hard duty. You are not chasing raw output, you are chasing efficiency at high water temperature.
- The cover matters even more than it does on a pool. A hard spa cover is doing most of the work overnight, every night.
- Most spas already have an electric element in the control box. The heat pump is there to stop that element running, not to replace the plumbing.
Option one: an integrated SpaNET SV heat pump
An integrated spa heat pump connects by cable to a SpaNET SV Series spa controller and is detected automatically, so the spa control switches its electric element off and lets the heat pump do the heating. There is no second keypad and no separate power circuit. You keep using the spa touchpad you already use, and the control system decides when the heat pump runs.
The Spanet 9.0kW SV Series Integrated Heat Pump is the one most Australian spas end up on. It delivers 8.6kW of heat while drawing 1.65kW, which is a COP of 5.21 at 24 degree ambient and 27 degree water. Running current is 7.8A. It suits spas over 2,500L, it heats to 41 degrees and it can also cool the water down to 10 degrees, which people in Perth and Brisbane use more than you would think.
Bigger spas and swim spas step up to the Spanet 12.0kW SV Series. Same integration, 12.0kW of output, 10.8A maximum input current, 40mm unions and a 5m lead. Warranty is 3 years on the compressor, 2 years parts and 1 year on site.
SpaNET SV heat pumps compared
| Spec | Spanet 9.0kW SV | Spanet 12.0kW SV |
|---|---|---|
| Model code | SN-HP-90P | SN-HP-120P |
| Heating capacity | 8.6kW | 12.0kW |
| Input power | 1.65kW | Refer to spec sheet |
| COP (24C air, 27C water) | 5.21 | Refer to spec sheet |
| Max rated current | 8.75A | 10.8A |
| Cooling capacity | 6.0kW (EER 3.5) | Heating focused |
| Water connections | 40mm PVC | 40mm unions |
| Noise | 49 dB(A) | Comparable |
| Dimensions (L x W x H) | 960 x 320 x 615mm | 980 x 312 x 615mm |
| Weight | 53kg | 62kg |
| Suits | Spas over 2,500L | Large spas and swim spas |
| Price | $2,850 | $4,000 |
Prices and specifications current as of September 2026, AUD including GST.
The catch with the integrated units is the prerequisite. They need a SpaNET SV Series control to work as designed. If your spa has an older or a different brand of control box, you are either upgrading the control or going standalone. An SV2 variable heat controller or an SV3 controller with touchpad is the usual upgrade path, and it is worth pricing both together before you commit, because a control plus a heat pump is a different budget to a heat pump on its own.
Option two: a small standalone pool heat pump
A small pool heat pump heats a spa perfectly well, it just runs off its own keypad instead of the spa control. You plumb it into the circulation line, it senses water temperature itself and it holds a setpoint independently of whatever the spa control is doing. This is the answer for any spa that is not on a SpaNET SV system, and for swim spas where the water volume is closer to a plunge pool than a spa.
The sensible sizes here are 7.5kW to 11kW. The Fairland Aqua X Essential 7.5kW full inverter at $2,242 is the entry point, and the Fairland Aqua X Essential 11kW at $2,860 covers a swim spa. If you want the quietest possible unit sitting a metre from where people are relaxing, the SensaHeat TDX 11kW at $3,150 is a top discharge design built for tight spaces. On a budget, the Guardian Eco Pro 9kW is $2,690, and the inverter version, the Guardian Platinum 9kW, is $3,046.
Go inverter if you can stretch to it. A spa sits at temperature almost all the time rather than heating up from cold, and that is exactly the condition where an inverter earns its money: it drops to a low hum to hold the setpoint instead of cycling hard on and off. Our guide to inverter heat pumps has the full explanation.
Sizing a heat pump for a spa
Match the heat pump to spa volume first, then adjust for whether the spa lives outdoors in a cold climate. Spas are small enough that the sizing table is short.
Spa volume vs heat pump size
| Spa volume | Type | Heat pump size |
|---|---|---|
| Under 1,500L | Small 2 to 3 seat spa | Element is usually enough, or 7.5kW |
| 1,500 to 3,000L | Standard 5 to 6 seat spa | 9kW |
| 3,000 to 5,000L | Large spa, small swim spa | 9kW to 12kW |
| 5,000L and up | Swim spa, spa and plunge combo | 12kW and up |
Cold climate, uncovered or year round use pushes you up a row. A well covered spa in Queensland can sit at the bottom of its band. If your spa volume is somewhere near a plunge pool, our pool heat pump sizing guide picks up where this table stops.
What a spa heat pump saves you
A heat pump cuts spa heating cost by roughly three quarters compared with the electric element in the spa control. The element converts one unit of electricity into one unit of heat. A heat pump moves heat instead of making it, so the 9.0kW SV unit turns 1.65kW of draw into 8.6kW of heat. That is the same ratio that makes heat pumps the default for pools, applied to a body of water you keep hot all year.
Real numbers depend on your tariff, your cover and how often the lid comes off. But the direction is not in doubt: a spa element is the single most expensive way to keep a spa warm, and it is the reason people go looking for a heat pump in the first place. The full method for working out a figure for your own setup is in our running cost guide.
Installation: sort these before it arrives
A spa heat pump needs a level base with clear airflow, a plumbing tie in to the circulation line and an electrician. Specifics worth checking before you order:
- Airflow. The 9.0kW SV moves 1,700 cubic metres of air an hour. Boxed into a tight alcove or shoved under decking it will short cycle its own cold discharge air and lose efficiency.
- Plumbing. Both SV units use 40mm connections into the spa circulation line, and the 9.0kW needs at least 3.0 cubic metres an hour of water flow. Your spa pump has to actually deliver that.
- Power. The integrated SV units connect by cable to the SV control, so no additional power circuit is needed. A standalone pool heat pump does need its own supply.
- Noise and neighbours. 49 dB(A) is quiet, but it is still a fan running at night beside a fence. Think about which way it faces.
- Weather. The 9.0kW SV is IPX5 rated with a titanium and PVC heat exchanger, so outdoor installation is fine. It still wants to sit up out of standing water.
Frequently asked questions
What size heat pump do I need for a spa in Australia?
A standard 5 to 6 seat spa holding 1,500 to 3,000L wants a 9kW heat pump. Large spas and small swim spas from 3,000 to 5,000L sit between 9kW and 12kW, and anything above 5,000L wants 12kW or more. Cold climates and uncovered spas push you up a size.
Can you use a pool heat pump on a spa?
Yes, a small pool heat pump in the 7.5kW to 11kW range heats a spa fine. It runs off its own keypad rather than the spa control, so you set the temperature on the heat pump instead of the spa touchpad. This is the standard answer for any spa that is not running a SpaNET SV Series control.
How much does it cost to run a spa heat pump?
Roughly a quarter of what the electric element in the spa control costs, because a heat pump moves heat rather than generating it. The Spanet 9.0kW SV draws 1.65kW to deliver 8.6kW of heat, a COP of 5.21. Your actual bill depends on tariff, spa cover and how often you use it.
Does a spa heat pump need a SpaNET controller?
The Spanet SV Series integrated heat pumps do, because they are detected by and controlled from a SpaNET SV Series spa control with no keypad of their own. Standalone pool heat pumps do not need any particular spa control, which is why they are the fallback for spas on other systems.
Can a spa heat pump cool the water in summer?
Some can. The Spanet 9.0kW SV delivers 6.0kW of cooling at an EER of 3.5 and will take spa water down to 10 degrees, and the Fairland Aqua X Essential units are heater and cooler models as well. It is a real feature in Perth, Brisbane and Darwin where an outdoor spa gets uncomfortably warm by February.
How long does a heat pump take to heat a spa?
A 9kW heat pump lifts a covered 2,500L spa by roughly 2 to 3 degrees an hour, so a cold start to 38 degrees is an overnight job, not a 20 minute one. That is why spas are left at temperature rather than heated on demand, and why the standing cost matters more than the heat up time.
Not sure which one suits your spa? Tell us the model
Give us your spa volume, the brand and model of your spa control and your postcode, and we will tell you whether an integrated SV unit or a standalone pool heat pump is the right call, and which size. It saves you buying a heat pump that will not talk to your spa.
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Heating a pool as well as the spa? Browse the full Heat Pumps collection, or start with our best seller, the Midea M Series 20kW with WiFi.
This guide is general information for Australian spa owners and is not a substitute for advice on your specific spa and site. Spa heat pumps are electrical appliances and all electrical work must be completed by a licensed electrician. Confirm compatibility with your spa control and final sizing with us or your spa technician before you buy.