It would probably be helpful if you gave some details about your pool -- what type, volume. Have you considered solar heat? Gas heaters are expensive to operate. Many of us here on the forum use solar panels. When you combine them with a solar blanket, you have a pretty significant gain in water temperature.
(I can't give you advice on particular gas heaters, but there are several members here who do use them who might be able to help you with suggestions.)
Welcome to the Pool Forum, by the way!
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