Product details:

Same water velocity through all tubes for faster heating Common union for installation or service, adapts to larger plumbing recommended for greater efficiencies Low NOx emissions meets clean air quality standards. Up to 18% savings by reducing pump run-time. 2inx 2 1/2inch CPVC Union Plumbing Connections Excellent salt water and chemical corrosion resistance. For model H350FDP and fits induced draft heater models H250IDL2, H350IDL2, and H400IDL2