A Generac spec sheet lists three critical figures for sizing: rated running kW at both natural gas and LP fuel, surge starting kW, and fuel consumption in cubic feet per hour for natural gas and gallons per hour for LP. These figures differ between fuel types because natural gas has a lower energy density than liquid propane, which reduces output by approximately 5 to 8 percent on some models.
Start with the rated kW column for your fuel type and compare it against your home load calculation. The load calculation adds the running wattage of every circuit that will be covered, then identifies the largest simultaneous motor starting scenario to check against surge capacity. If the rated kW on natural gas for a 22kW Guardian is listed as 19.5kW, that is the correct continuous output number for sizing on gas, not the 22kW LP rating.
Additional spec sheet data to review includes operating ambient temperature range (confirms suitability for your climate), sound output in dB at 23 feet (relevant for noise ordinance compliance), fuel inlet pressure requirements (must match your gas utility or regulator output), and physical dimensions and weight for pad sizing and delivery access. Our licensed master electrician staff can walk through any spec sheet with you. Contact us or browse the full Generac lineup. Free Freight Insurance Included.