Pool heat pumps can be a very smart investment, particularly if you are currently running a standard electrical resistance unit or an older gas unit.
Newer gas pool heaters can be quite efficient so the cost savings with a heat pump can be marginal - some people will still think it is worth it, and it is certainly something to bear in mind when the time comes to replace the old heater. (It is a good idea to plan for this rather than be forced into making a snap decision.)
Electric pool heaters of the old kind are rated as 100% efficient - this means that all the electricity goes to heating the pool. Sounds good, does it not? The trouble is that electricity production, down the line at the generator, is not 100% efficient... Hence it can cost a lot more (in cash terms and in environmental terms) to heat your pool with a 100% efficient electrical heater than with a gas heater rated at 60% efficient.
Luckily there is an electrical option that is cheaper and more efficient. Heat pumps for swimming pools are often rated at 500% efficiency or more! This means that they produce five units of heat for every electrical unit used (it is why it is sometimes called 'free energy').
So when it comes to swimming pool heaters, the heat pump is certainly well worth a close look. It is probably worth getting a detailed professional opinion however, since the heat pump needs can be affected by many things - not just the average air temperature and pool size, but also the amount of wind and the average nighttime temperature.