Pool heat pumps generally fall into two types:-
- Inverter driven
Inverter driven heat pumps are a newer generation of heat pumps. They are variable speed which allows the fan and compressor to run at different speeds according to the demand from the pool.
On/Off heat pumps can only run at 100% or turn off. They are not variable speed.
The advantage of inverter heat pumps over on/off models is:-
1. More efficient = lower running costs: When inverter heat pumps run at reduced speed their efficiency (COP) rises drastically. Inverter driven heat pumps can have efficiencies (COPs) of up to 14.
This means that for every 1kw of power used, they can return up to 14kw of heat to the pool. The maximum COP for on/off heat pumps is around 5 to 6
2. They are generally much quieter as they do not need to always run at 100%. Once the pool reaches the desired temperature, the inverter driven heat pump can slow itself down and run at a reduced speed eg 30%. When running at a reduced speed, the noise is significantly reduced.
3. Built in “soft-start”. When inverter heat pumps start, they gradually increase their speed from zero up to the required running speed. This gentle start up avoids the power “spike” that can be encountered with on-off type heat pumps.
This “soft-start” feature of inverter driven heat pumps prevents issues such as the house lights flickering when the heat pump starts or electrical breakers tripping on the consumer unit.
At the moment, both on/off and inverter driven heat pumps are available.