Rose | 
05 31st, 2010| 
This is not an easy answer. It depends on a lot of things.
Like:
How much sun you get on an average day?
What temperature are you looking to heat the pool to?
What is your average temperature in the summer without a heater?
How far is the pool from the filter system, and how far is your house from the pool & Equiptment.
What size is your pool and what size pump is on it.
Depending on your answers to these questions, your solution may vary.
Solar heaters can be bought very easily and are not terribly expensive,but their can be drawbacks. Installation can be expensive, generally they have limitations to the temps they can heat to, they are limited by the amount of sun you get, and if they are not installed properly they will not heat the pool at all, and could even lower the temp of the pool. The biggest benefit is that once the system has been bought and installed there is no ongoing fuel cost. So eventually they will pay for themselves and then some. One other potential issue is that depending on the size of your pool pump in relation to the size of your pool and the potential location for your solar heater, it may be necessary to purchase a pump of a larger horsepower and water flow. This would add increased cost to the project.
Fossil fuel heaters (Gas or Propane) are more expensive than solar and have ongoing costs for operation, but can provide you with benefits that no other heater can. They can heater to higher temps (Usually limited to the heaters thermostat), and they will heat the pool much faster than any type of heater. (depending on the desired temp and the starting temp, they can heat in as little as an hour to 8 hours if properly sized to your pool) Again the biggest drawback to this is the initial cost (depending on size $900 – $2,500) and the on-going bill for the fuel. Same as the heater in your house
Heat Pumps – These are the most energy efficient heaters available. The drawbacks to these are the initial cost (Much higher than the other types, anywhere from $2,500 – $3,700) and the heating time. These heaters are designed to be a constant heater and build the heat up slowly over the course of a few days to a week depending on the pools current temp and the desired temp. The big benefit to these though is they will cost you way less than any fossil fuel heater you can find and again the energy efficiency usually pays for the heater over time. The only other issue is these heaters generally don’t work well when the outside air temps are below 50 degrees. Most times this is not much of an issue as most people are not swimming when it is that cold out.
Regardless of what type of heater you put on the pool, you should also invest in a solar cover or blanket. Anytime the outside air temperature is lower than your pool water temperature, the pool should be covered. Otherwise all the heat that is being put into it will just evaporate out of it. (As you see the steam rise from the pool, you should envision your dollars going with it)
The best thing to do would be to find a good pool dealer in your area and go and talk to them. I would suggest talking to a few different pool professionals to see what they recommend for your area. Just remember that different people will have their own personal preferences, and some people will be motivated by the money they could make by selling you one type over the other. Try to find someone who sells all three types as they will be less likely to try to pressure you into something.
