Key Specifications at a Glance
Full DC inverter R290 pool heat pumps from villa pools to resort pools. Heating and cooling in one unit; fixed-speed commercial units for 40–130 kW.
How Pool Temperature Control Works
A pool temperature control system moves thermal energy between the air and your pool water. In heating mode, it extracts warmth from the air and delivers it to the pool. In cooling mode, it reverses the cycle to remove excess heat — delivering 5-7 times more thermal energy transfer than the electricity it consumes.
1. Absorb Heat from Air
The DC fan draws ambient air across the evaporator coil, where R290 refrigerant absorbs thermal energy and evaporates at low temperature.
2. Compress and Amplify
The Panasonic DC inverter compressor raises the refrigerant temperature and pressure, concentrating the harvested energy into usable high-grade heat.
3. Transfer to Pool Water
Hot refrigerant passes through the dual-coil titanium heat exchanger, transferring heat directly to the circulating pool water safely and efficiently.
Advanced Pool Temperature Control Technology
Every iSPA unit combines premium components and intelligent controls to deliver reliable, efficient pool temperature control — heating and cooling — in any climate.
R290 Natural Refrigerant System
- GWP of 3A natural refrigerant, outside the HFC phase-down that is removing R410A and R32. Small charge, optional factory leak sensor, A3-rated installation by our engineers.
- Fujikoki Electronic Expansion ValvePrecision superheat control across all operating conditions. Faster response than mechanical TXVs for optimal efficiency.
- SANHUA 4-Way Reversing ValveSeamlessly switches between heating and cooling modes. Heat your pool in winter, cool it in summer.
DC Inverter Components
- Panasonic DC Inverter CompressorVariable-speed operation matches output to demand. No hard starts, reduced wear, lower noise, and peak efficiency at partial loads.
- DC Brushless Fan MotorStepless speed control matched to the compressor. Quiet running with precise airflow management.
- Dual-Coil Titanium ExchangerTwo titanium coils in a PVC shell — more transfer area than a single coil. Resists saltwater, chlorine and bromine; no corrosion, no contamination.
Full-Colour Touchscreen
Detachable colour touchscreen for temperature, scheduling, mode and diagnostics — with live power-consumption display.
Wi-Fi App + OTA Updates
Phone app for remote monitoring and control, RS485 for building systems, and over-the-air software updates.
Soundproofed Cabinet
Weatherproof cabinet with an insulated compressor compartment — 37 dB(A) at 1 m on the smallest model. Quiet enough beside the pool.
Why Choose iSPA Over Gas or Electric?
Traditional pool heating methods are expensive, inefficient, and increasingly obsolete. The iSPA delivers superior results at a fraction of the running cost.
Gas / Electric Pool Heaters
- COP of 0.8-1.0 -- most energy wasted as exhaust
- High monthly gas or electricity bills
- Combustion produces CO and NOx emissions
- Gas supply infrastructure required
- Short lifespan of heating elements and burners
- No cooling capability — pools overheat in tropical climates
Karnot iSPA Temperature Control
- COP 7 at full load, 20+ when cruising -- 5-7x more efficient
- Up to 85% lower running costs
- Zero on-site emissions or combustion
- Only requires a standard electrical connection
- Long-life titanium exchanger and DC compressor
- Both heating and cooling modes built in
COP 7 at Full Load
Seven kWh of pool heat for every 1 kWh of electricity at full output — and 22 to 26 when the inverter cruises at low speed.
Heat and Cool
Heats pool water to 40 °C; cools it down to 5 °C. Perfect for tropical pools that overheat in the afternoon, and for keeping a pool swimmable in the cool months.
Quiet Operation
Noise levels from just 37 dB(A) on smaller models. DC inverter runs at low speed when demand is light.
Wide Ambient Range
Operates from -20 °C to 43 °C ambient. Reliable performance in tropical, temperate, and cold climates.
Saltwater Compatible
Dual-coil titanium exchanger is immune to saltwater, chlorine, and bromine corrosion.
Natural Refrigerant
R290 with a GWP of 3 -- not a synthetic gas on a phase-down schedule. Efficient operation further reduces the carbon footprint.
Ideal Applications
The iSPA range covers every pool temperature control need — heating pools in cooler weather and cooling them when tropical sun pushes water temperatures too high — from backyard pools to large commercial facilities.
Residential Pools
Maintain the perfect pool temperature year-round — heat when it's cold, cool when tropical sun overheats your water. Quiet operation and compact design suit any backyard.
Commercial Pools
Gyms, sports centres, and swim schools. Reliable heating for high-usage pools with demanding temperature requirements.
Hotel and Resort Pools
Precise temperature control for guests 365 days a year — cooling overheated pools in summer, heating in winter. Silent operation preserves the premium guest experience.
Water Parks
Three-phase inverter models (23-40 kW) and fixed-speed commercial units (40-130 kW) heat large pools and lazy rivers. Cascade multiple units for any size.
Spas and Hot Tubs
Precise temperature control up to 40 °C. Maintain therapeutic water temperatures efficiently without electric elements.
Complete iSPA Product Range
10 inverter models from 10 kW to 40 kW. Single-phase (220V) for villas and small resorts; three-phase (380V) for commercial pools. Fixed-speed commercial units extend the range to 130 kW — ask us.
Single Phase (220V)
Three Phase (380V)
All prices: Contact for Quotation | Multiple units can be cascaded for pools larger than 140 m³
Pool Temperature Control Calculator
Find the right iSPA model for your pool. Enter your pool details below and we will recommend the ideal unit for heating and cooling.
Find Your Ideal iSPA Model
Your Recommended iSPA Model
UK: £0.17/kWh electricity
Need an Accurate Quote?
This calculator provides estimates based on typical conditions. For a precise sizing analysis including local climate data, pool construction, and wind exposure, request a complimentary pool temperature control assessment.
Ready to Control Your Pool Temperature?
Request your free pool temperature control assessment and receive a detailed recommendation for heating and cooling your installation.
Request Free AssessmentFrequently Asked Questions
What COP do Karnot iSPA pool temperature control systems achieve?
Karnot iSPA Inverter pool heat pumps deliver a COP of 6.6 to 7.4 at full load (air 27 C, water 26 C) and 22 to 26 when cruising at low speed. In plain terms: 7 kWh of pool heat for every 1 kWh of electricity at full output, and two to three times that for most of the day.
Can the iSPA cool my pool as well as heat it?
Yes. Every iSPA Inverter model heats and cools. It heats pool water up to 40 degrees C and cools it down to 5 degrees C. A SANHUA 4-way valve automatically reverses the refrigerant cycle.
Is the iSPA safe for saltwater pools?
Yes. All Karnot iSPA Inverter models use a dual-coil titanium tube heat exchanger in a PVC shell that is fully resistant to saltwater, chlorine, and bromine corrosion. Titanium is the gold standard for pool heat exchanger longevity.
What size pool can the iSPA heat?
The iSPA Inverter range covers pools from 25 cubic metres up to 140 cubic metres. The smallest model (iSPA 10 at 10 kW) suits pools of 25-40 cubic metres, while the largest (iSPA 40T at 40 kW, three-phase) handles pools of 80-140 cubic metres. Multiple units can be cascaded for larger pools, and fixed-speed commercial units cover 40-130 kW.
What refrigerant does the iSPA use?
The iSPA Inverter uses R290 (propane), a natural refrigerant with a Global Warming Potential of 3. It sits outside the HFC phase-down that is removing R410A and R32 from the market, so the unit you buy today is not built on a refrigerant with a shrinking future.
Can the iSPA operate in cold weather?
Yes. The Karnot iSPA Inverter operates in air temperatures from -20 degrees C to 43 degrees C. The full DC inverter system with Panasonic compressor and electronic expansion valve automatically adjusts to maintain performance across this range.