terminology Chuck Shaw

chuck shaw

If using the term, "direct vent boiler", either gas or oil fired, when ordering a heating appliance, what would you expect from your supply house? Just curious, seems I have caused some confusion for my local counter man

Chuck

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Bill NTSG

Direct vent

means direct vent. An appliance that requires no chimney and no powerventer. The appliance is factory approved or listed for direct vent. Am I close ?

Dave Yates (PAH)

Direct vent implies that the appliance both exhausts and gets combustion air via piping to the atmosphere.

Indirect venting implies that the appliance exhausts directly to atmosphere while utilizing indoor air for combustion.

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Unknown

Direct Vent

The difference between Direct Vent and Mechanical Exhausting relative to code is what is confusing. Some people think they are one in the same. They are not, Direct Vent has different clearance to windows, doors and openings. Under 50,000 BTU's 9" over 50,000 12" (that may change with new code and give more options).
The appliance vents flue products to outdoors with out power vent, and gets air back in from outdoors, in some case by using a concentric vent in other cases two seperate pipes. The direct vent equipment may have a "Combustion Air Blower" but does not pressurize the vent. Mechanical exhausting uses a power venter and every part of the vent pipe is positive pressure after the power venter and must be sealed. It must be terminated 4' from windows, doors and openings. I find there is much confusion on the part of many in the trades and even some inspectors. The best way to know is to read the installation manual and look at rating plate to see if classified "Direct Vent" I also have a Troubleshooting Guide that clears this up.

Boilerpro

Direct vent versus power vent, etc.

To add to the confusion, there is equipment available that is wall vented, but does not use a fan for exhaust...ie some newer gas water heaters and gas fireplaces.

Boilerpro