Coates ST Series Compact Electric Spa Heaters are ideal for hot tubs, spas and small residential swimming pools. Standard features include Incoloy heating elements, manual reset high temp limit, pressure switch, heavy-duty contactors, element “on” light and close differential thermostat. The stainless steel tank optimizes heat transfer by efficiently directing water flow over the Incoloy elements. The built-in pressure switch prevents operation when no water flow is present. Flow rates are between 15 and 80 gallons per minute. Specifications: 17-1/2"L x 4"W x 14"H; 1-1/2 x 2" union connections for PVC pipes; 240 Volt.