Getting it right when you are sizing swimming pool heaters is very important. If you buy a unit that is not up to the job then you will be miserable about your cold pool. But if you overdo it, you will end up paying more than you need to for the unit, which might also make you a little down. Heaters that are too large are likely to be wasteful too, so we need to put some thought into buying the right size.
The problem is that many factors affect the heater we need. Almost all of these have to do with heat loss, so are interesting even if you are not in the market for a new pool heater - you can still improve your current heating performance. The first key difference is that above ground swimming pool heaters need to work much harder than their rivals heating pools that are in the ground. This is because significant amounts of heat are lost through the sides of the pool. Insulation will help however, and should be considered by anyone with an above ground installation.
Another factor to consider whether you are looking at solar heating for swimming pools, electric swimming pool heaters, gas, oil or wood, is the location of the pool. Namely, does it have a wind break. The biggest loss (apart from the sides of a raised pool) is caused by wind taking away the warm surface layer of air. If you can install a wind break of trees or a fence, it will help.
As you can see, there are a few things to consider when thinking about buying one of those new-fangled swimming pool heat pumps.