Direct Vent vs Power Vent

Dick Charland

Both "direct" vent and power vented equipment do not use a chimney as you indicated. They more often than not are both vented either through the sidewall or can be vented up through the roof under limitations specified by the manufacturer as to venting material, diameter and total equivalent length which takes into account vent fittings. Both methods require that combustion air and vent terminations be located proximate to each other, on the same wall when sidewall venting as well as extending together through the roof. This allows for balanced or equal pressure on the appliance. Direct vent equipment does not use a mechanical fan to evacuate the flue gases from the appliance. The system is generally pressurized by the mechanical fan present in the burner portion of the equipment. Accordingly, it is critical that the appliance as well as venting and combustion air piping be sealed to prevent flue gases from escaping. Direct vent systems are always sealed combustion.

Power venters on the other hand are a mechanical fan used to draw the flue gases out of the appliance. This method may be used in addition to a power burner such as on oil as well as with atmospheric gas burners. Because the unit works under a negative pressure there is generally no requirement for sealed combustion. There are some that combines a power venter with an atmospheric gas boiler that is sealed. Good practice should include provision of adequate combustion air to the appliance. Power venters unfortunately tend to be noisey and present another mechanical device requiring periodic service and maintenance.

Hope this helps.

JIMBO_2

Direct Vent vs Power Vent

I'm hearing all this chatter about Direct Vent and Power Vent. What is the exact difference between the two? Since neither one uses the chminey, are they the same?

Dale

Direct vs power

Direct by nfpa 54 defin is:" ALL air for combustion is derived directly from outside atmosphere AND all flue gases are discharged to the outside atmosphere." from 3.3.68 Note that no motor is defined as many direct vent appliances don't have a blower. Power vent isn't defined but 3.3.237 and 238 are the "mechanical draft" definitions. Air can come from the inside but there there must be a motor to push or pull or both the vent product to the outdoors.