Vertical inverter heating for smaller pond installations
Compare Thermotec Apex 8kW and 11kW inverter heat pumps for suitable koi ponds and swimming pools. The vertical air outlet offers a compact layout, with Wi-Fi control and a heating setting range that starts at 9°C. Select the model for the installation’s heat loss and circulation rather than pond volume alone.
Read the Thermotec Apex buying guide and model comparison, or browse our complete air source heat pump range.
Choosing a Thermotec Apex heat pump
Choosing between Apex 8kW and 11kW
The Apex range provides two individual model choices. Compare the output at matching air and water test temperatures, together with the recommended water flow, electrical input and cabinet dimensions. The nominal kW rating identifies the model; it is not a fixed amount of heat available throughout every winter day. A covered, insulated pond normally loses less heat than an exposed pond of the same volume.
Temperature control and winter operation
The Apex manual gives a heating water range of 9–40°C and a heating ambient range of −15°C to 43°C. This permits consideration for a 12°C winter pond target, but the controller range alone does not establish adequate capacity. Allow for local conditions, surface area, exposed filtration and the temperature difference between the water and air. Make temperature changes gradually on a stocked pond and monitor the water with a suitable thermometer.
Why choose vertical air discharge?
The fan sends discharged air upwards instead of forwards. This can make some equipment layouts easier, but the heater still needs its full working clearances. The manual’s installation diagram specifies at least 1,000mm above and 500–1,000mm around the unit depending on the side. Check the diagram’s orientation before positioning fences, walls or overhead structures. Do not enclose the heater in a sealed equipment box.
Circulation and controls
Apex uses 50mm water connections and requires a separate circulation pump supplying clean filtered water. Check delivered flow through the installed system, allow for an appropriate bypass and support the pipework independently. Wi-Fi can help with monitoring, while inverter control adjusts output as demand changes. Neither feature removes the need for safe local isolation, unobstructed airflow and maintenance access.
Compare the models in this range
Open an individual model for its full technical data, current price, installation guidance and delivery information. Electrical phase is shown separately so similarly named versions can be compared correctly.
| Model | Electrical supply | Air discharge |
|---|---|---|
| Thermotec Apex 8kW Inverter Pond Heat Pump | Single phase | Vertical |
| Thermotec Apex 11kW Inverter Pond Heat Pump | Single phase | Vertical |
Heating output is not electrical consumption
kW can describe either the heat delivered to the water or the electricity used, so check which figure is quoted. In performance tables, A refers to air temperature and W to water temperature, in degrees Celsius. COP compares delivered heat with electrical input at a stated test condition. Compare like-for-like figures rather than using the highest advertised efficiency to predict your annual bill.
Before you order
Measure the water volume and surface area, decide on your target temperature and heating season, and note the cover and insulation. Check the available electrical supply, delivered water flow and outdoor installation space. A suitable cover can reduce the heat that must be replaced. Tell us about exposed filters, pipework and wind so that these are included in the recommendation. During frost, follow the manual’s circulation and drain-down instructions; switching an idle heater off does not remove trapped water.
More help with your heating system
Our pond heating guide explains winter sizing, covers and system choices. Use the air source heat pump filters to compare electrical supply, output, control type and budget across ranges. For circulation equipment, explore our pond pumps and check the delivered flow through the complete circuit.
Other ranges to compare
- Poolex Silverline Top heat pumps
- Poolex Nano FI heat pumps
- Thermotec Nova heat pumps
- Thermotec Edge heat pumps
- Thermotec Neo heat pumps
Different ranges suit different temperatures, seasons and installations. Compare the controller settings and cold-weather output as well as nominal kW before changing to an alternative.
