SWG Power VenterSizing The Venter Size the SWG or ComboVent venter based on the input firing rate of the appliance. If the power venter is being used to vent multiple appliances, add the input firing rates for each appliance and use that total to size the venter. Knowing the total input BTU/hr. for gas, or GPH for oil, the venter can be sized from Table 1. Select the venter rated closest to the total input BTU or GPH for installation. If the input of the appliance is higher than the maximum allowable for that size SWG or CV, move to the next larger size SWG or CV.
Do not select a venter with a maximum BTU/hr. or GPH lower than the appliance. The equivalent feet of vent pipe for the installation must be calculated. Based on the vent pipe diameter to be used, compare the calculated equivalent feet of vent pipe with the maximum equivalent feet allowable for the venter (See Table 1). If the calculated equivalent feet is greater than that allowed for the venter, increase the diameter of the vent pipe to be used and refer to the table or use the next larger size SWG or CV venter.
Note: In Table 1, the maximum equivalent footage allowable for the vent pipe is given for two points, the maximum BTU/hr. venting capacity and at 60% of the maximum. This allows for estimating values between the two given points.