Which uses more gas - larger or smaller heater?

[rcmcdee]

We have a small 12,000 gallon indoor pool that previously was heated with a RayPak 333,000 BTU unit that just died. As I am looking into replacement possibilities it seems that heater was grossly oversized. I am considering a Hayward H150FDP 150,000 BTU unit but my wife hears that we should buy the H250FDP 250,000 BTU unit because it will heat faster. Given that it is an indoor pool in NY's Hudson Valley that will be used year round, we will basically be maintaining a constant temperature. Which of these units would use more gas to maintain that constant temperature? I currently cycle the pump for 3 hours twice daily.

TIA,
Robb

[Denniswiseman]

Obviously the larger one would burn more gas but come up to temperature quicker and shut off
The smaller one will take longer to get up to temperature burning more gas for a longer period
The solution to to get an accurately sized heater for your pool

[lourdeswalter]

I have Hayward product heated my 20'x40', 36,000 gallon pool from 72 degrees to 87 degrees in about two to theee days during (average) 82 degree days. Works great so far. Costs far less than competitors. Hoping that it will last 7-10 years. At this point, I highly recommend visit High Quality Pool site to read more useful infomation about above ground pool heaters.