Gas Powered Heaters
These are the most common type and they have the advantage of being able to provide heat faster than other options as they are more powerful. Units designed for above-ground pools (such as the Pentair Minimax NT) typically supply around 100k BTU, on the other hand a heater designed for an in ground pool (such as the Jandy/Zodiac LXi) can provide up to about 400k BTU. This is particularly useful if you heat the pool intermittently and therefore need to raise the temperature quickly. Click Here to read more.