Thank you for writing to me. Focustemp has not made heaters in at least 4 or 5 years before they went out of business. That one is probably the 55,000 BTU model. For a 24 foot round pool; 15,000 gallons we like to see a 100,000 BTU heater unless you use a blanket on the pool all the time and then a 70,000 to 80,000 BTU heater is OK depending on how long you want to your season to last. That heater is too small for your pool. I would suggest a larger heat pump from a company that has been around for at least 20 years with a very long warranty. If you tell me where you live and what months you want to swim I can suggest some for your area.